MPLS VPN--Inter-AS--IPv4 BGP Label Distribution

Table Of Contents

MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

Contents

Prerequisites for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

Restrictions for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

Information About MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

MPLS VPN—Inter-AS—IPv4 BGP Label Distribution Overview

BGP Routing Information

Types of BGP Messages and MPLS Labels

How BGP Sends MPLS Labels with Routes

Using Route Maps to Filter Routes

How to Configure MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

Configuring the ASBRs to Exchange IPv4 Routes and MPLS Labels

Configuring the Route Reflectors to Exchange VPNv4 Routes

Configuring the Route Reflectors to Reflect Remote Routes in Its AS

Creating Route Maps

Configuring a Route Map for Arriving Routes

Configuring a Route Map for Departing Routes

Applying the Route Maps to the ASBRs

Verifying the MPLS VPN—Inter-AS—IPv4 BGP Label Distribution Configuration

Verifying the Route Reflector Configuration

Verifying that CE1 Has Network Reachability Information for CE2

Verifying that PE1 Has Network Layer Reachability Information for CE2

Verifying that PE2 Has Network Reachability Information for CE2

Verifying the ASBR Configuration

Configuration Examples for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

Configuring Inter-AS Using BGP to Distribute Routes and MPLS Labels Over an MPLS VPN Service Provider Example

Route Reflector 1 Configuration Example (MPLS VPN Service Provider)

ASBR1 Configuration Example (MPLS VPN Service Provider)

Route Reflector 2 Configuration Example (MPLS VPN Service Provider)

ASBR2 Configuration Example (MPLS VPN Service Provider)

Configuring Inter-AS Using BGP to Distribute Routes and MPLS Labels Over a Non MPLS VPN Service Provider Example

Route Reflector 1 Configuration Example (Non MPLS VPN Service Provider)

ASBR1 Configuration Example (Non MPLS VPN Service Provider)

Route Reflector 2 Configuration Example (Non MPLS VPN Service Provider)

ASBR2 Configuration Example (Non MPLS VPN Service Provider)

ASBR3 Configuration Example (Non MPLS VPN Service Provider)

Route Reflector 3 Configuration Example (Non MPLS VPN Service Provider)

ASBR4 Configuration Example (Non MPLS VPN Service Provider)

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

Glossary

MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

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This feature enables you to set up a Virtual Private Network (VPN) service provider network so that the autonomous system boundary routers (ASBRs) exchange IPv4 routes with Multiprotocol Label Switching (MPLS) labels of the provider edge (PE) routers. Route reflectors (RRs) exchange VPNv4 routes by using multihop, multiprotocol, External Border Gateway Protocol (EBGP). This configuration saves the ASBRs from having to store all the VPNv4 routes. Using the route reflectors to store the VPNv4 routes and forward them to the PE routers results in improved scalability.

The MPLS VPN—Inter-AS—IPv4 BGP Label Distribution feature has the following benefits:

•Having the route reflectors store VPNv4 routes results in improved scalability—This configuration scales better than other configurations where the ASBR holds all of the VPNv4 routes and forwards the routes based on VPNv4 labels. With this configuration, route reflectors hold the VPNv4 routes, which simplifies the configuration at the border of the network.

•Enables a non-VPN core network to act as a transit network for VPN traffic—You can transport IPv4 routes with MPLS labels over a non MPLS VPN service provider.

•Eliminates the need for any other label distribution protocol between adjacent LSRs—If two adjacent label switch routers (LSRs) are also BGP peers, BGP can handle the distribution of the MPLS labels. No other label distribution protocol is needed between the two LSRs.

•Includes EBGP multipath support to enable load balancing for IPv4 routes across autonomous system (AS) boundaries.

Feature History for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

Release	Modification
12.0(21)ST	This feature was introduced.
12.0(22)S	This feature was implemented on the Cisco 12000 series routers (for specific line cards supported, see Table 1) and integrated into Cisco IOS Release 12.0(22)S.
12.0(23)S	Support was added for the Cisco 12000 Series Eight-Port OC-3c/STM-1c ATM Line Card (8-Port OC-3 ATM) and the Cisco 12000 Series Three-Port Gigabit Ethernet Line Card (3-Port GbE).
12.2(13)T	This feature was integrated into Cisco IOS Release 12.2(13)T.
12.0(24)S	Support was added for the Cisco 12000 Series One-Port 10-Gigabit Ethernet Line Card (1-Port 10-GbE) and the Cisco 12000 Series Modular Gigabit Ethernet/ Fast Ethernet Line Card (Modular GbE/FE) and implemented on Cisco IOS 12.0(24)S.
12.2(14)S	This feature was integrated into Cisco IOS Release 12.2(14)S and implemented on Cisco 7200 and Cisco 7500 series routers.
12.0(27)S	Support was added for EBGP multipath on the provider edge (PE)-customer edge (CE) links.
12.2(28)SB	This feature was integrated into Cisco IOS Release 12.2(28)SB.

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Note Software images for Cisco 12000 series Internet routers have been deferred to Cisco IOS Release 12.0(27)S1.

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Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

Contents

•Prerequisites for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

•Restrictions for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

•Information About MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

•How to Configure MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

•Configuration Examples for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

•Additional References

•Command Reference

•Glossary

Prerequisites for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

The network must be properly configured for MPLS VPN operation before you configure this feature.

Table 1 lists the Cisco 12000 series line card support added by Cisco IOS S releases.

Table 1 Cisco I2000 Series Line Card Support Added for Cisco IOS S Releases 

Type	Line Cards	Cisco IOS Release Supported
Packet Over SONET (POS)	4-Port OC-3 POS 8-Port OC-3 POS 16-Port OC-3 POS 1-Port OC-12 POS 4-Port OC-12 POS 1-Port OC-48 POS 4-Port OC-3 POS ISE 8-Port OC-3 POS ISE 16-Port OC-3 POS ISE 4-Port OC-12 POS ISE 1-Port OC-48 POS ISE	12.0(22)S, 12.0(23)S, 12.0(27)S
Electrical Interface	6-Port DS3 12-Port DS3 6-Port E3 12-Port E3	12.0(22)S, 12.0(23)S, 12.0(27)S
Ethernet	3-Port GbE	12.0(23)S, 12.0(27)S
Asynchronous Transfer Mode (ATM)	4-Port OC-3 ATM 1-Port OC12 ATM 4-Port OC-12 ATM 8-Port OC-3 ATM	12.0(22)S, 12.0(23)S, 12.0(27)S 12.0(23)S
Channelized Interface	2-Port CHOC-3 6-Port Ch T3 (DS1) 1-Port CHOC-12 (DS3) 1-Port CHOC-12 (OC-3) 4-Port CHOC-12 ISE 1-Port CHOC-48 ISE	12.0(22)S, 12.0(23)S, 12.0(27)S

Restrictions for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

This feature includes the following restrictions:

•For networks configured with EBGP multihop, a labeled switched path (LSP) must be established between nonadjacent routers. (RFC 3107)

•The PE routers must run images that support BGP label distribution. Otherwise, you cannot run EBGP between them.

•Point-to-Point Protocol (PPP) encapsulation on the ASBRs is not supported with this feature.

•The physical interfaces that connect the BGP speakers must support Cisco Express Forwarding (CEF) or distributed CEF and MPLS.

Information About MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

To configure MPLS VPN—Inter-AS—IPv4 BGP Label Distribution, you need the following information:

•MPLS VPN—Inter-AS—IPv4 BGP Label Distribution Overview

•BGP Routing Information

•Types of BGP Messages and MPLS Labels

•How BGP Sends MPLS Labels with Routes

•Using Route Maps to Filter Routes

MPLS VPN—Inter-AS—IPv4 BGP Label Distribution Overview

This feature enables you to set up a VPN service provider network to exchange IPv4 routes with MPLS labels. You can configure the VPN service provider network as follows:

•Route reflectors exchange VPNv4 routes by using multihop, multiprotocol EBGP. This configuration also preserves the next hop information and the VPN labels across the autonomous systems.

•A local PE router (for example, PE1 in Figure 1) needs to know the routes and label information for the remote PE router (PE2). This information can be exchanged between the PE routers and ASBRs in one of two ways:

–Internal Gateway Protocol (IGP) and Label Distribution Protocol (LDP): The ASBR can redistribute the IPv4 routes and MPLS labels it learned from EBGP into IGP and LDP and vice versa.

–Internal Border Gateway Protocol (IBGP) IPv4 label distribution: The ASBR and PE router can use direct IBGP sessions to exchange VPNv4 and IPv4 routes and MPLS labels.

Alternatively, the route reflector can reflect the IPv4 routes and MPLS labels learned from the ASBR to the PE routers in the VPN. This is accomplished by enabling the ASBR to exchange IPv4 routes and MPLS labels with the route reflector. The route reflector also reflects the VPNv4 routes to the PE routers in the VPN (as mentioned in the first bullet). For example, in VPN1, RR1 reflects to PE1 the VPNv4 routes it learned and IPv4 routes and MPLS labels learned from ASBR1. Using the route reflectors to store the VPNv4 routes and forward them through the PE routers and ASBRs allows for a scalable configuration.

•ASBRs exchange IPv4 routes and MPLS labels for the PE routers by using EBGP. This enables load balancing across CSC boundaries.

Figure 1 VPNs Using EBGP and IBGP to Distribute Routes and MPLS Labels

BGP Routing Information

BGP routing information includes the following items:

•A network number (prefix), which is the IP address of the destination.

•Autonomous system (AS) path, which is a list of the other ASs through which a route passes on its way to the local router. The first AS in the list is closest to the local router; the last AS in the list is farthest from the local router and usually the AS where the route began.

•Path attributes, which provide other information about the AS path, for example, the next hop.

Types of BGP Messages and MPLS Labels

MPLS labels are included in the update messages that a router sends. Routers exchange the following types of BGP messages:

•Open Messages—After a router establishes a TCP connection with a neighboring router, the routers exchange open messages. This message contains the AS number to which the router belongs and the IP address of the router who sent the message.

•Update Messages—When a router has a new, changed, or broken route, it sends an update message to the neighboring router. This message contains the Network Layer Reachability Information (NLRI), which lists the IP addresses of the usable routes. The update message also includes any routes that are no longer usable. The update message also includes path attributes and the lengths of both the usable and unusable paths. Labels for VPNv4 routes are encoded in the update message as specified in RFC 2858. The labels for the IPv4 routes are encoded in the update message as specified in RFC 3107.

•Keepalive Messages—Routers exchange keepalive messages to determine if a neighboring router is still available to exchange routing information. The router sends these messages at regular intervals. (Sixty seconds is the default for Cisco routers.) The keepalive message does not contain routing data; it only contains a message header.

•Notification Messages—When a router detects an error, it sends a notification message.

How BGP Sends MPLS Labels with Routes

When BGP (EBGP and IBGP) distributes a route, it can also distribute an MPLS label that is mapped to that route. The MPLS label mapping information for the route is carried in the BGP update message that contains the information about the route. If the next hop is not changed, the label is preserved.

When you issue the neighbor send-label command on both BPG routers, the routers advertise to each other that they can then send MPLS labels with the routes. If the routers successfully negotiate their ability to send MPLS labels, the routers add MPLS labels to all outgoing BGP updates.

Using Route Maps to Filter Routes

When both routers are configured to distribute routes with MPLS labels, all the routes are encoded with the multiprotocol extensions and contain an MPLS label. You can use a route map to control the distribution of MPLS labels between routers. Route maps enable you to specify the following:

•For a router distributing MPLS labels, you can specify which routes are distributed with an MPLS label.

•For a router receiving MPLS labels, you can specify which routes are accepted and installed in the BGP table.

How to Configure MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

This section contains the following procedures:

•Configuring the ASBRs to Exchange IPv4 Routes and MPLS Labels

•Configuring the Route Reflectors to Exchange VPNv4 Routes

•Configuring the Route Reflectors to Reflect Remote Routes in Its AS

•Creating Route Maps

•Applying the Route Maps to the ASBRs

•Verifying the MPLS VPN—Inter-AS—IPv4 BGP Label Distribution Configuration

Figure 2 shows the following sample configuration:

•The configuration consists of two VPNs.

•The ASBRs exchange the IPv4 routes with MPLS labels.

•The route reflectors exchange the VPNv4 routes using multlihop MPLS EBGP.

•The route reflectors reflect the IPv4 and VPNv4 routes to the other routers in its AS.

Figure 2 Configuring Two VPN Service Providers to Exchange IPv4 Routes and MPLS Labels

Configuring the ASBRs to Exchange IPv4 Routes and MPLS Labels

Perform this task to configure the ASBRs so that they can distribute BGP routes with MPLS labels.

SUMMARY STEPS

1. enable

2. configure terminal

3. router bgp as-number

4. neighbor {ip-address | peer-group-name} remote-as as-number

5. address-family ipv4 [multicast | unicast | vrf vrf-name]

6. maximum paths number-paths (optional for EBGP multipath between the CSC-PE and CSC-CEs)

7. neighbor {ip-address | peer-group-name} activate

8. neighbor ip-address send-label

9. exit-address-family

10. end

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	router bgp as-number Example: Router(config)# router bgp 100	Configures a BGP routing process and places the router in router configuration mode. •The as-number argument indicates the number of an autonomous system that identifies the router to other BGP routers and tags the routing information passed along. Valid numbers are from 0 to 65535. Private autonomous system numbers that can be used in internal networks range from 64512 to 65535.
Step 4	neighbor {ip-address | peer-group-name} remote-as as-number Example: Router(config-router)# neighbor hh.0.0.1 remote-as 200	Adds an entry to the BGP or multiprotocol BGP neighbor table. •The ip-address argument specifies the IP address of the neighbor. •The peer-group-name argument specifies the name of a BGP peer group. •The as-number argument specifies the autonomous system to which the neighbor belongs.
Step 5	address-family ipv4 [multicast | unicast | vrf vrf-name] Example: Router(config-router)# address-family ipv4	Enters address family configuration mode for configuring routing sessions such as BGP that use standard IPv4 address prefixes. •The multicast keyword specifies IPv4 multicast address prefixes. •The unicast keyword specifies IPv4 unicast address prefixes. •The vrf vrf-name keyword and argument specifies the name of the VPN routing/forwarding instance (VRF) to associate with subsequent IPv4 address family configuration mode commands.
Step 6	maximum-paths number-paths Example: Router(config-router)# maximum-paths 2	(Optional) Controls the maximum number of parallel routes an IP routing protocol can support. The number-paths argument specifies the maximum number of parallel routes an IP routing protocol installs in a routing table, in the range from 1 to 6.
Step 7	neighbor {ip-address | peer-group-name} activate Example: Router(config-router-af)# neighbor hh.0.0.1 activate	Enables the exchange of information with a neighboring router. •The ip-address argument specifies the IP address of the neighbor. •The peer-group-name argument specifies the name of a BGP peer group.
Step 8	neighbor ip-address send-label Example: Router(config-router-af)# neighbor hh.0.0.1 send-label	Enables a BGP router to send MPLS labels with BGP routes to a neighboring BGP router. •The ip-address argument specifies the IP address of the neighboring router.
Step 9	exit-address-family Example: Router(config-router-af)# exit-address-family	Exits from the address family submode.
Step 10	end Example: Router(config-router-af)# end	(Optional) Exits to privileged EXEC mode.

Configuring the Route Reflectors to Exchange VPNv4 Routes

Perform this task to enable the route reflectors to exchange VPNv4 routes by using multihop, multiprotocol EBGP.

This procedure also specifies that the next hop information and the VPN label are preserved across the autonomous systems. This procedure uses RR1 as an example.

SUMMARY STEPS

1. enable

2. configure terminal

3. router bgp as-number

4. neighbor {ip-address | peer-group-name} remote-as as-number

5. address-family vpnv4 [unicast]

6. neighbor {ip-address | peer-group-name} ebgp-multihop [ttl]

7. neighbor {ip-address | peer-group-name} activate

8. neighbor {ip-address | peer-group-name} next-hop unchanged

9. exit-address-family

10. end

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	router bgp as-number Example: Router(config)# router bgp 100	Configures a BGP routing process and places the router in router configuration mode. •The as-number argument indicates the number of an autonomous system that identifies the router to other BGP routers and tags the routing information passed along. Valid numbers are from 0 to 65535. Private autonomous system numbers that can be used in internal networks range from 64512 to 65535. The AS number identifies RR1 to routers in other autonomous systems.
Step 4	neighbor {ip-address | peer-group-name} remote-as as-number Example: Router(config-router)# neighbor bb.bb.bb.bb remote-as 200	Adds an entry to the BGP or multiprotocol BGP neighbor table. •The ip-address argument specifies the IP address of the neighbor. •The peer-group-name argument specifies the name of a BGP peer group. •The as-number argument specifies the autonomous system to which the neighbor belongs.
Step 5	address-family vpnv4 [unicast] Example: Router(config-router)# address-family vpnv4	Enters address family configuration mode for configuring routing sessions, such as BGP, that use standard Virtual Private Network Version 4 (VPNv4) address prefixes. •The optional unicast keyword specifies VPNv4 unicast address prefixes.
Step 6	neighbor {ip-address | peer-group-name} ebgp-multihop [ttl] Example: Router(config-router-af)# neighbor bb.bb.bb.bb ebgp-multihop 255	Accepts and attempts BGP connections to external peers residing on networks that are not directly connected. •The ip-address argument specifies the IP address of the BGP-speaking neighbor. •The peer-group-name argument specifies the name of a BGP peer group. •The ttl argument specifies the time-to-live in the range from 1 to 255 hops.
Step 7	neighbor {ip-address | peer-group-name} activate Example: Router(config-router-af)# neighbor bb.bb.bb.bb activate	Enables the exchange of information with a neighboring router. •The ip-address argument specifies the IP address of the neighbor. •The peer-group-name argument specifies the name of a BGP peer group.
Step 8	neighbor {ip-address | peer-group-name} next-hop unchanged Example: Router(config-router-af)# neighbor ip-address next-hop unchanged	Enables an External BGP (EBGP) multihop peer to propagate the next hop unchanged. •The ip-address argument specifies the IP address of the next hop. •The peer-group-name argument specifies the name of a BGP peer group that is the next hop.
Step 9	exit-address-family Example: Router(config-router-af)# exit-address-family	Exits from the address family submode.
Step 10	end Example: Router(config-router-af)# end	(Optional) Exits to privileged EXEC mode.

Configuring the Route Reflectors to Reflect Remote Routes in Its AS

Perform this task to enable the RR to reflect the IPv4 routes and labels learned by the ASBR to the PE routers in the AS.

This is accomplished by making the ASBR and PE router route reflector clients of the RR. This procedure also explains how to enable the RR to reflect the VPNv4 routes.

SUMMARY STEPS

1. enable

2. configure terminal

3. router bgp as-number

4. address-family ipv4 [multicast | unicast | vrf vrf-name]

5. neighbor {ip-address | peer-group-name} activate

6. neighbor ip-address route-reflector-client

7. neighbor ip-address send-label

8. exit-address-family

9. address-family vpnv4 [unicast]

10. neighbor {ip-address | peer-group-name} activate

11. neighbor ip-address route-reflector-client

12. exit-address-family

13. end

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	router bgp as-number Example: Router(config)# router bgp 100	Configures a BGP routing process and places the router in router configuration mode. •The as-number argument indicates the number of an autonomous system that identifies the router to other BGP routers and tags the routing information passed along. Valid numbers are from 0 to 65535. Private autonomous system numbers that can be used in internal networks range from 64512 to 65535.
Step 4	address-family ipv4 [multicast | unicast | vrf vrf-name] Example: Router(config-router)# address-family ipv4	Enters address family configuration mode for configuring routing sessions such as BGP that use standard IPv4 address prefixes. •The multicast keyword specifies IPv4 multicast address prefixes. •The unicast keyword specifies IPv4 unicast address prefixes. •The vrf vrf-name keyword and argument specifies the name of the VPN routing and forwarding instance (VRF) to associate with subsequent IPv4 address family configuration mode commands.
Step 5	neighbor {ip-address | peer-group-name} activate Example: Router(config-router-af)# neighbor ee.ee.ee.ee activate	Enables the exchange of information with a neighboring router. •The ip-address argument specifies the IP address of the neighbor. •The peer-group-name argument specifies the name of a BGP peer group.
Step 6	neighbor ip-address route-reflector-client Example: Router(config-router-af)# neighbor ee.ee.ee.ees route-reflector-client	Configures the router as a BGP route reflector and configures the specified neighbor as its client. •The ip-address argument specifies the IP address of the BGP neighbor being identified as a client.
Step 7	neighbor ip-address send-label Example: Router(config-router-af)# neighbor ee.ee.ee.ee send-label	Enables a BGP router to send MPLS labels with BGP routes to a neighboring BGP router. •The ip-address argument specifies the IP address of the neighboring router.
Step 8	exit-address-family Example: Router(config-router-af)# exit-address-family	Exits from the address family submode.
Step 9	address-family vpnv4 [unicast] Example: Router(config-router)# address-family vpnv4	Enters address family configuration mode for configuring routing sessions, such as BGP, that use standard VPNv4 address prefixes. •The optional unicast keyword specifies VPNv4 unicast address prefixes.
Step 10	neighbor {ip-address | peer-group-name} activate Example: Router(config-router-af)# neighbor ee.ee.ee.ee activate	Enables the exchange of information with a neighboring router. •The ip-address argument specifies the IP address of the neighbor. •The peer-group-name argument specifies the name of a BGP peer group.
Step 11	neighbor ip-address route-reflector-client Example: Router(config-router-af)# neighbor ee.ee.ee.ee route-reflector-client	Enables the RR to pass IBGP routes to the neighboring router.
Step 12	exit-address-family Example: Router(config-router-af)# exit-address-family	Exits from the address family submode.
Step 13	end Example: Router(config-router-af)# end	(Optional) Exits to privileged EXEC mode.

Creating Route Maps

The following procedures enable the ASBRs to send MPLS labels with the routes specified in the route maps. Further, the ASBRs accept only the routes that are specified in the route map.

•Configuring a Route Map for Arriving Routes

•Configuring a Route Map for Departing Routes

Route maps enable you to specify which routes are distributed with MPLS labels. Route maps also enable you to specify which routes with MPLS labels a router receives and adds to its BGP table.

Route maps work with access lists. You enter the routes into an access list and then specify the access list when you configure the route map.

Configuring a Route Map for Arriving Routes

This configuration is optional.

Perform this task to create a route map to filter arriving routes. You create an access list and specify the routes that the router should accept and add to the BGP table.

SUMMARY STEPS

1. enable

2. configure terminal

3. router bgp as-number

4. route-map route-map-name [permit | deny] [sequence-number]

5. match ip address {access-list-number | access-list-name} [... access-list-number |... access-list-name]

6. match mpls-label

7. end

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	router bgp as-number Example: Router(config)# router bgp 100	Configures a BGP routing process and places the router in router configuration mode. •The as-number argument indicates the number of an autonomous system that identifies the router to other BGP routers and tags the routing information passed along. Valid numbers are from 0 to 65535. Private autonomous system numbers that can be used in internal networks range from 64512 to 65535.
Step 4	route-map route-map-name [permit | deny] [sequence-number] Example: Router(config-router)# route-map IN permit 11	Creates a route map with the name you specify. •The permit keyword allows the actions to happen if all conditions are met. •The deny keyword prevents any actions from happening if all conditions are met. •The sequence-number argument allows you to prioritize route maps. If you have multiple route maps and want to prioritize them, assign each one a number. The route map with the lowest number is implemented first, followed by the route map with the second lowest number, and so on.
Step 5	match ip address {access-list-number | access-list-name} [... access-list-number |... access-list-name] Example: Router(config-route-map)# match ip address 2	Distributes any routes that have a destination network number address that is permitted by a standard or extended access list, or performs policy routing on packets. •The access-list-number argument is a number of a standard or extended access list. It can be an integer from 1 to 199. •The access-list-name argument is a name of a standard or extended access list. It can be an integer from 1 to 199.
Step 6	match mpls-label Example: Router(config-route-map)# match mpls-label	Redistributes routes that include MPLS labels if the routes meet the conditions specified in the route map.
Step 7	end Example: Router(config-route-map)# end	(Optional) Exits to privileged EXEC mode.

Configuring a Route Map for Departing Routes

This configuration is optional.

Perform this task to create a route map to filter departing routes. You create an access list and specify the routes that the router should distribute with MPLS labels.

SUMMARY STEPS

1. enable

2. configure terminal

3. router bgp as-number

4. route-map route-map-name [permit | deny] [sequence-number]

5. match ip address {access-list-number | access-list-name} [... access-list-number |... access-list-name]

6. set mpls label

7. end

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	router bgp as-number Example: Router(config)# router bgp 100	Configures a BGP routing process and places the router in router configuration mode. •The as-number argument indicates the number of an autonomous system that identifies the router to other BGP routers and tags the routing information passed along. Valid numbers are from 0 to 65535. Private autonomous system numbers that can be used in internal networks range from 64512 to 65535.
Step 4	route-map route-map-name [permit | deny] [sequence-number] Example: Router(config-router)# route-map OUT permit 10	Creates a route map with the name you specify. •The permit keyword allows the actions to happen if all conditions are met. •The deny keyword prevents the actions from happening if all conditions are met. •The sequence-number argument allows you to prioritize route maps. If you have multiple route maps and want to prioritize them, assign each one a number. The route map with the lowest number is implemented first, followed by the route map with the second lowest number, and so on.
Step 5	match ip address {access-list-number | access-list-name} [... access-list-number |... access-list-name] Example: Router(config-route-map)# match ip address 1	Distributes any routes that have a destination network number address that is permitted by a standard or extended access list, or performs policy routing on packets. •The access-list-number argument is a number of a standard or extended access list. It can be an integer from 1 to 199. •The access-list-name argument is a name of a standard or extended access list. It can be an integer from 1 to 199.
Step 6	set mpls-label Example: Router(config-route-map)# set mpls-label	Enables a route to be distributed with an MPLS label if the route matches the conditions specified in the route map.
Step 7	end Example: Router(config-route-map)# end	Exits to privileged EXEC mode.

Applying the Route Maps to the ASBRs

This configuration is optional.

Perform this task to enable the ASBRs to use the route maps.

SUMMARY STEPS

1. enable

2. configure terminal

3. router bgp as-number

4. address-family ipv4 [multicast | unicast | vrf vrf-name}

5. neighbor ip-address route-map route-map-name in

6. neighbor ip-address route-map route-map-name out

7. neighbor ip-address send-label

8. exit-address-family

9. end

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	router bgp as-number Example: Router(config)# router bgp 100	Configures a BGP routing process and places the router in router configuration mode. •The as-number argument indicates the number of an autonomous system that identifies the router to other BGP routers and tags the routing information passed along. Valid numbers are from 0 to 65535. Private autonomous system numbers that can be used in internal networks range from 64512 to 65535.
Step 4	address-family ipv4 [multicast | unicast | vrf vrf-name] Example: Router(config-router)# address-family ipv4	Enters address family configuration mode for configuring routing sessions such as BGP that use standard IPv4 address prefixes. •The multicast keyword specifies IPv4 multicast address prefixes. •The unicast keyword specifies IPv4 unicast address prefixes. •The vrf vrf-name keyword and argument specifies the name of the VRF to associate with subsequent IPv4 address family configuration mode commands.
Step 5	neighbor ip-address route-map route-map-name in Example: Router(config-router-af)# neighbor ip-address route-map IN in	Applies a route map to incoming routes. •The ip-address argument specifies the router to which the route map is to be applied. •The route-map-name argument specifies the name of the route map. •The in keyword applies the route map to incoming routes.
Step 6	neighbor ip-address route-map route-map-name out Example: Router(config-router-af)# neighbor ww.ww.ww.ww route-map OUT out	Applies a route map to outgoing routes. •The ip-address argument specifies the router to which the route map is to be applied. •The route-map-name argument specifies the name of the route map. •The out keyword applies the route map to outgoing routes.
Step 7	neighbor ip-address send-label Example: Router(config-router-af)# neighbor ww.ww.ww.ww send-label	Advertises the ability of the router to send MPLS labels with routes. •The ip-address argument specifies the router that is enabled to send MPLS labels with routes.
Step 8	exit-address-family Example: Router(config-router-af)# exit-address-family	Exits from the address family submode.
Step 9	end Example: Router(config-route-af)# end	(Optional) Exits to privileged EXEC mode.

Verifying the MPLS VPN—Inter-AS—IPv4 BGP Label Distribution Configuration

If you use route reflectors to distribute the VPNv4 routes and use the ASBRs to distribute the IPv4 labels, use the following procedures to help verify the configuration:

•Verifying the Route Reflector Configuration

•Verifying that CE1 Has Network Reachability Information for CE2

•Verifying that PE1 Has Network Layer Reachability Information for CE2

•Verifying that PE2 Has Network Reachability Information for CE2

•Verifying the ASBR Configuration

Use Figure 3 as a reference of the configuration.

Figure 3 Configuring Two VPN Service Providers to Exchange IPv4 Routes and MPLS Labels

Verifying the Route Reflector Configuration

Perform this task to verify the route reflector configuration.

SUMMARY STEPS

1. enable

2. show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name} [summary] [labels]

3. disable

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name} [summary] [labels] Example: Router# show ip bgp vpnv4 all summary Example: Router# show ip bgp vpnv4 all labels	(Optional) Displays VPN address information from the BGP table. •Use the show ip bgp vpnv4 command with the all and summary keywords to verify that a multihop, multiprotocol, EBGP session exists between the route reflectors and that the VPNv4 routes are being exchanged between the route reflectors. The last two lines of the command output show the following information: –Prefixes are being learned from PE1 and then passed to RR2. –Prefixes are being learned from RR2 and then passed to PE1. •Use the show ip bgp vpnv4 command with the all and labels keywords to verify that the route reflectors are exchanging VPNv4 label information.
Step 3	disable Example: Router# disable	(Optional) Exits to user EXEC mode.

Verifying that CE1 Has Network Reachability Information for CE2

Perform this task to verify that router CE1 has NLRI for router CE2.

SUMMARY STEPS

1. enable

2. show ip route [ip-address [mask] [longer-prefixes]] | [protocol [process-id]] | [list access-list-number | access-list-name]

3. disable

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	show ip route [ip-address [mask] [longer-prefixes]] | [protocol [process-id]] | [list access-list-number | access-list-name] Example: Router# show ip route nn.nn.nn.nn Example: Router# show ip route	Displays the current state of the routing table. •Use the show ip route command with the ip-address argument to verify that CE1 has a route to CE2. •Use the show ip route command to verify the routes learned by CE1. Make sure that the route for CE2 is listed.
Step 3	disable Example: Router# disable	(Optional) Exits to user EXEC mode.

Verifying that PE1 Has Network Layer Reachability Information for CE2

Perform this task to verify that router PE1 has NLRI for router CE2.

SUMMARY STEPS

1. enable

2. show ip route vrf vrf-name [connected] [protocol [as-number] [tag] [output-modifiers]] [list number [output-modifiers]] [profile] [static [output-modifiers]] [summary [output-modifiers]] [supernets-only [output-modifiers]] [traffic-engineering [output-modifiers]]

3. show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name} [ip-prefix/length [longer-prefixes] [output-modifiers]] [network-address [mask] [longer-prefixes] [output-modifiers]] [cidr-only] [community] [community-list] [dampened-paths] [filter-list] [flap-statistics] [inconsistent-as] [neighbors] [paths [line]] [peer-group] [quote-regexp] [regexp] [summary] [tags]

4. show ip cef [vrf vrf-name] [network [mask]] [longer-prefixes] [detail]

5. show mpls forwarding-table [{network {mask | length} | labels label [- label] | interface interface | next-hop address | lsp-tunnel [tunnel-id]}] [detail]

6. show ip bgp [network] [network-mask] [longer-prefixes]

7. show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name} [summary] [labels]

8. disable

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	show ip route vrf vrf-name [connected] [protocol [as-number] [tag] [output-modifiers]] [list number [output-modifiers]] [profile] [static [output-modifiers]] [summary [output-modifiers]] [supernets-only [output-modifiers]] [traffic-engineering [output-modifiers]] Example: Router# show ip route vrf vpn1 nn.nn.nn.nn	(Optional) Displays the IP routing table associated with a VRF. •Use the show ip route vrf command to verify that router PE1 learns routes from router CE2 (nn.nn.nn.nn).
Step 3	show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name} [ip-prefix/length [longer-prefixes] [output-modifiers]] [network-address [mask] [longer-prefixes] [output-modifiers]] [cidr-only] [community] [community-list] [dampened-paths] [filter-list] [flap-statistics] [inconsistent-as] [neighbors] [paths [line]] [peer-group] [quote-regexp] [regexp] [summary] [tags] Example: Router# show ip bgp vpnv4 vrf vpn1 nn.nn.nn.nn Example: Router# show ip bgp vpn4 all nn.nn.nn.nn	(Optional) Displays VPN address information from the BGP table. •Use the show ip bgp vpnv4 command with the vrf or all keyword to verify that router PE2 is the BGP next-hop to router CE2.
Step 4	show ip cef [vrf vrf-name] [network [mask]] [longer-prefixes] [detail] Example: Router# show ip cef vrf vpn1 nn.nn.nn.nn	(Optional) Displays entries in the forwarding information base (FIB) or displays a summary of the FIB. •Use the show ip cef command to verify that the Cisco Express Forwarding (CEF) entries are correct.
Step 5	show mpls forwarding-table [{network {mask | length} | labels label [- label] | interface interface | next-hop address | lsp-tunnel [tunnel-id]}] [detail] Example: Router# show mpls forwarding-table	(Optional) Displays the contents of the MPLS forwarding information base (LFIB). •Use the show mpls forwarding-table command to verify the IGP label for the BGP next hop router (AS boundary).
Step 6	show ip bgp [network] [network-mask] [longer-prefixes] Example: Router# show ip bgp ff.ff.ff.ff	(Optional) Displays entries in the BGP routing table. •Use the show ip bgp command to verify the label for the remote egress PE router (PE2).
Step 7	show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name} [summary] [labels] Example: Router# show ip bgp vpnv4 all labels	(Optional) Displays VPN address information from the BGP table. •Use the show ip bgp vpnv4 all summary command to verify the VPN label of CE2, as advertised by PE2.
Step 8	disable Example: Router# disable	(Optional) Exits to user EXEC mode.

Verifying that PE2 Has Network Reachability Information for CE2

Perform this task to ensure that PE2 can access CE2.

SUMMARY STEPS

1. enable

2. show ip route vrf vrf-name [connected] [protocol [as-number] [tag] [output-modifiers]] [list number [output-modifiers]] [profile] [static [output-modifiers]] [summary [output-modifiers]] [supernets-only [output-modifiers]] [traffic-engineering [output-modifiers]]

3. show mpls forwarding-table [vrf vpn-name] [{network {mask | length} | labels label [-label] | interface interface | next-hop address | lsp-tunnel [tunnel-id]}] [detail]

4. show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name} [summary] [labels]

5. show ip cef [vrf vrf-name] [network [mask]] [longer-prefixes] [detail]

6. disable

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	show ip route vrf vrf-name [connected] [protocol [as-number] [tag] [output-modifiers]] [list number [output-modifiers]] [profile] [static [output-modifiers]] [summary [output-modifiers]] [supernets-only [output-modifiers]] [traffic-engineering [output-modifiers]] Example: Router# show ip route vrf vpn1 nn.nn.nn.nn	(Optional) Displays the IP routing table associated with a VRF. •Use the show ip route vrf command to check the VPN routing and forwarding table for CE2. The output provides next hop information.
Step 3	show mpls forwarding-table [vrf vpn-name] [{network {mask | length} | labels label [-label] | interface interface | next-hop address | lsp-tunnel [tunnel-id]}] [detail] Example: Router# show mpls forwarding-table vrf vpn1 nn.nn.nn.nn	(Optional) Displays the contents of the LFIB. •Use the show mpls forwarding-table command with the vrf keyword to check the VPN routing and forwarding table for CE2. The output provides the label for CE2 and the outgoing interface.
Step 4	show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name} [summary] [labels] Example: Router# show ip bgp vpnv4 all labels	(Optional) Displays VPN address information from the BGP table. •Use the show ip bgp vpnv4 command with the all and labels keywords to check the VPN label for CE2 in the multiprotocol BGP table.
Step 5	show ip cef [vrf vrf-name] [network [mask]] [longer-prefixes] [detail] Example: Router# show ip cef <vrf-name> nn.nn.nn.nn	(Optional) Displays entries in the FIB or displays a summary of the FIB. •Use the show ip cef command to check the CEF entry for CE2. The command output shows the local label for CE2 and the outgoing interface.
Step 6	disable Example: Router# disable	(Optional) Exits to user EXEC mode.

Verifying the ASBR Configuration

Perform this task to verify that the ASBRs exchange IPv4 routes with MPLS labels or IPv4 routes without labels as prescribed by a route map.

SUMMARY STEPS

1. enable

2. show ip bgp [network] [network-mask] [longer-prefixes]

3. show ip cef [vrf vrf-name] [network [mask]] [longer-prefixes] [detail]

4. disable

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	show ip bgp [network] [network-mask] [longer-prefixes] Example: Router# show ip bgp ff.ff.ff.ff Example: Router# show ip bgp bb.bb.bb.bb	(Optional) Displays entries in the BGP routing table. •Use the show ip bgp command to check that— –ASBR1 receives an MPLS label for PE2 from ASBR2. –ASBR1 received from ASBR2 IPv4 routes for RR2 without labels. If the command output does not display MPLS label information, the route was received without an MPLS label. –ASBR2 distributes an MPLS label for PE2 to ASBR1. –ASBR2 does not distribute a label for RR2 to ASBR1.
Step 3	show ip cef [vrf vrf-name] [network [mask]] [longer-prefixes] [detail] Example: Router# show ip cef ff.ff.ff.ff Example: Router# show ip cef bb.bb.bb.bb	(Optional) Displays entries in the FIB or displays a summary of the FIB. •Use the show ip cef command from ASBR1 and ASBR2 to check that— –The CEF entry for PE2 is correct. –The CEF entry for RR2 is correct.
Step 4	disable Example: Router# disable	(Optional) Exits to user EXEC mode.

Configuration Examples for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution

Configuration examples for MPLS VPN—Inter-AS—IPv4 BGP Label Distribution feature include the following:

•Configuring Inter-AS Using BGP to Distribute Routes and MPLS Labels Over an MPLS VPN Service Provider Example

•Configuring Inter-AS Using BGP to Distribute Routes and MPLS Labels Over a Non MPLS VPN Service Provider Example

Configuring Inter-AS Using BGP to Distribute Routes and MPLS Labels Over an MPLS VPN Service Provider Example

Configuration examples for Inter-AS using BGP to distribute routes and MPLS labels over an MPLS VPN service provider included in this section are as follows:

•Route Reflector 1 Configuration Example (MPLS VPN Service Provider)

•ASBR1 Configuration Example (MPLS VPN Service Provider)

•Route Reflector 2 Configuration Example (MPLS VPN Service Provider)

•ASBR2 Configuration Example (MPLS VPN Service Provider)

Figure 4 shows two MPLS VPN service providers. The service provider distributes the VPNv4 routes between the route reflectors. They distribute the IPv4 routes with MPLS labels between the ASBRs.

The configuration example shows the two techniques you can use to distribute the VPNv4 routes and the IPv4 routes with MPLS labels of the remote RRs and PEs to the local RRs and PEs:

•AS 100 uses the RRs to distribute the VPNv4 routes learned from the remote RRs. The RRs also distribute the remote PE address and label learned from ASBR1 using IPv4 + labels.

•In AS 200, the IPv4 routes that ASBR2 learned are redistributed into IGP.

Figure 4 Distributing IPv4 Routes and MPLS Labels Between MPLS VPN Service Providers

Route Reflector 1 Configuration Example (MPLS VPN Service Provider)

The configuration example for RR1 specifies the following:

•RR1 exchanges VPNv4 routes with RR2 using multiprotocol, multihop EBGP.

•The VPNv4 next hop information and the VPN label are preserved across the autonomous systems.

•RR1 reflects to PE1:

–The VPNv4 routes learned from RR2

–The IPv4 routes and MPLS labels learned from ASBR1

ip subnet-zero

ip cef

!

interface Loopback0

 ip address aa.aa.aa.aa 255.255.255.255

 no ip directed-broadcast

!

interface Serial1/2

 ip address dd.0.0.2 255.0.0.0

 no ip directed-broadcast

 clockrate 124061

!   

router ospf 10

 log-adjacency-changes

 auto-cost reference-bandwidth 1000

 network aa.aa.aa.aa 0.0.0.0 area 100

 network dd.0.0.0 0.255.255.255 area 100

!

router bgp 100

 bgp cluster-id 1

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor ee.ee.ee.ee remote-as 100

 neighbor ee.ee.ee.ee update-source Loopback0

 neighbor ww.ww.ww.ww remote-as 100

 neighbor ww.ww.ww.ww update-source Loopback0

 neighbor bb.bb.bb.bb remote-as 200

 neighbor bb.bb.bb.bb ebgp-multihop 255

 neighbor bb.bb.bb.bb update-source Loopback0

 no auto-summary

 !

address-family ipv4

 neighbor ee.ee.ee.ee activate

 neighbor ee.ee.ee.ee route-reflector-client                !IPv4+labels session to PE1

 neighbor ee.ee.ee.ee send-label

 neighbor ww.ww.ww.ww activate

 neighbor ww.ww.ww.ww route-reflector-client                !IPv4+labels session to ASBR1

 neighbor ww.ww.ww.ww send-label

 no neighbor bb.bb.bb.bb activate

 no auto-summary

 no synchronization

 exit-address-family

 !

address-family vpnv4

 neighbor ee.ee.ee.ee activate

 neighbor ee.ee.ee.ee route-reflector-client                !VPNv4 session with PE1

 neighbor ee.ee.ee.ee send-community extended

 neighbor bb.bb.bb.bb activate             

 neighbor bb.bb.bb.bb next-hop-unchanged                    !MH-VPNv4 session with RR2

 neighbor bb.bb.bb.bb send-community extended                 !with next hop unchanged     

 exit-address-family

!

ip default-gateway 3.3.0.1

no ip classless

!

snmp-server engineID local 00000009020000D0584B25C0

snmp-server community public RO

snmp-server community write RW

no snmp-server ifindex persist

snmp-server packetsize 2048

!

end

ASBR1 Configuration Example (MPLS VPN Service Provider)

ASBR1 exchanges IPv4 routes and MPLS labels with ASBR2.

In this example, ASBR1 uses route maps to filter routes.

•A route map called OUT specifies that ASBR1 should distribute the PE1 route (ee.ee) with labels and the RR1 route (aa.aa) without labels.

•A route map called IN specifies that ASBR1 should accept the PE2 route (ff.ff) with labels and the RR2 route (bb.bb) without labels.

ip subnet-zero

mpls label protocol tdp

!

interface Loopback0

 ip address ww.ww.ww.ww 255.255.255.255

 no ip directed-broadcast

 no ip route-cache

 no ip mroute-cache

!

interface Ethernet0/2

 ip address hh.0.0.2 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

!

interface Ethernet0/3

 ip address dd.0.0.1 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

 mpls label protocol ldp

 mpls ip

!

router ospf 10

 log-adjacency-changes

 auto-cost reference-bandwidth 1000

 redistribute connected subnets

 passive-interface Ethernet0/2

 network ww.ww.ww.ww 0.0.0.0 area 100

 network dd.0.0.0 0.255.255.255 area 100

router bgp 100

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor aa.aa.aa.aa remote-as 100

 neighbor aa.aa.aa.aa update-source Loopback0

 neighbor hh.0.0.1 remote-as 200

 no auto-summary

 !

!

address-family ipv4                       ! Redistributing IGP into BGP 

 redistribute ospf 10                     ! so that PE1 & RR1 loopbacks 

 neighbor aa.aa.aa.aa activate            ! get into the BGP table

 neighbor aa.aa.aa.aa send-label

 neighbor hh.0.0.1 activate

 neighbor hh.0.0.1 advertisement-interval 5

 neighbor hh.0.0.1 send-label

 neighbor hh.0.0.1 route-map IN in        ! accepting routes in route map IN.

 neighbor hh.0.0.1 route-map OUT out      ! distributing routes in route map OUT.

 neighbor kk.0.0.1 activate

 neighbor kk.0.0.1 advertisement-interval 5

 neighbor kk.0.0.1 send-label

 neighbor kk.0.0.1 route-map IN in        ! accepting routes in route map IN.

 neighbor kk.0.0.1 route-map OUT out      ! distributing routes in route map OUT.

 no auto-summary

 no synchronization

 exit-address-family

!

ip default-gateway 3.3.0.1

ip classless

!

access-list 1 permit ee.ee.ee.ee log                !Setting up the access lists

access-list 2 permit ff.ff.ff.ff log

access-list 3 permit aa.aa.aa.aa log

access-list 4 permit bb.bb.bb.bb log

route-map IN permit 10                              !Setting up the route maps

 match ip address 2

 match mpls-label

!

route-map IN permit 11

 match ip address 4

!

route-map OUT permit 12

 match ip address 3

!

route-map OUT permit 13

 match ip address 1

 set mpls-label

!

end

Route Reflector 2 Configuration Example (MPLS VPN Service Provider)

RR2 exchanges VPNv4 routes with RR1 through multihop, multiprotocol EBGP. This configuration also specifies that the next hop information and the VPN label are preserved across the autonomous systems.

ip subnet-zero

ip cef

!

interface Loopback0

 ip address bb.bb.bb.bb 255.255.255.255

 no ip directed-broadcast

!

interface Serial1/1

 ip address ii.0.0.2 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

!

router ospf 20

 log-adjacency-changes

 network bb.bb.bb.bb 0.0.0.0 area 200

 network ii.0.0.0 0.255.255.255 area 200

!

router bgp 200

 bgp cluster-id 1

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor aa.aa.aa.aa remote-as 100

 neighbor aa.aa.aa.aa ebgp-multihop 255

 neighbor aa.aa.aa.aa update-source Loopback0

 neighbor ff.ff.ff.ff remote-as 200

 neighbor ff.ff.ff.ff update-source Loopback0

 no auto-summary

 !

 address-family vpnv4

 neighbor aa.aa.aa.aa activate

 neighbor aa.aa.aa.aa next-hop-unchanged              !Multihop VPNv4 session with RR1 

 neighbor aa.aa.aa.aa send-community extended              !with next-hop-unchanged

 neighbor ff.ff.ff.ff activate

 neighbor ff.ff.ff.ff route-reflector-client          !VPNv4 session with PE2

 neighbor ff.ff.ff.ff send-community extended

 exit-address-family

!

ip default-gateway 3.3.0.1

no ip classless

!

end

ASBR2 Configuration Example (MPLS VPN Service Provider)

ASBR2 exchanges IPv4 routes and MPLS labels with ASBR1. However, in contrast to ASBR1, ASBR2 does not use the RR to reflect IPv4 routes and MPLS labels to PE2. ASBR2 redistributes the IPv4 routes and MPLS labels learned from ASBR1 into IGP. PE2 can now reach these prefixes.

ip subnet-zero

ip cef

!

mpls label protocol tdp

!

interface Loopback0

 ip address xx.xx.xx.xx 255.255.255.255

 no ip directed-broadcast

!

interface Ethernet1/0

 ip address hh.0.0.1 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

!

interface Ethernet1/2

 ip address jj.0.0.1 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

 mpls label protocol tdp

 mpls ip

 !

router ospf 20

 log-adjacency-changes

 auto-cost reference-bandwidth 1000

 redistribute connected subnets

 redistribute bgp 200 subnets           ! Redistributing the routes learned from 

 passive-interface Ethernet1/0               ! ASBR1(EBGP+labels session) into IGP 

 network xx.xx.xx.xx 0.0.0.0 area 200         ! so that PE2 will learn them  

 network jj..0.0 0.255.255.255 area 200

 !

router bgp 200

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor bb.bb.bb.bb remote-as 200

 neighbor bb.bb.bb.bb update-source Loopback0

 neighbor hh.0.0.2 remote-as 100

 no auto-summary

 !

address-family ipv4

 redistribute ospf 20                         ! Redistributing IGP into BGP  

 neighbor hh.0.0.2 activate                   ! so that PE2 & RR2 loopbacks

 neighbor hh.0.0.2 advertisement-interval 5   ! will get into the BGP-4 table.

 neighbor hh.0.0.2 route-map IN in 

 neighbor hh.0.0.2 route-map OUT out

 neighbor hh.0.0.2 send-label

 neighbor kk.0.0.2 activate 

 neighbor kk.0.0.2 advertisement-interval 5 

 neighbor kk.0.0.2 route-map IN in 

 neighbor kk.0.0.2 route-map OUT out

 neighbor kk.0.0.2 send-label

 no auto-summary

 no synchronization

 exit-address-family

! 

address-family vpnv4

 neighbor bb.bb.bb.bb activate

 neighbor bb.bb.bb.bb send-community extended

 exit-address-family

 !

ip default-gateway 3.3.0.1

ip classless

!

access-list 1 permit ff.ff.ff.ff log          !Setting up the access lists

access-list 2 permit ee.ee.ee.ee log

access-list 3 permit bb.bb.bb.bb log

access-list 4 permit aa.aa.aa.aa log

route-map IN permit 11                       !Setting up the route maps

 match ip address 2

 match mpls-label

!

route-map IN permit 12

 match ip address 4

!

route-map OUT permit 10

 match ip address 1

 set mpls-label

!

route-map OUT permit 13

 match ip address 3

end

Configuring Inter-AS Using BGP to Distribute Routes and MPLS Labels Over a Non MPLS VPN Service Provider Example

Configuration examples for Inter-AS using BGP to distribute routes and MPLS labels over a non MPLS VPN service provider included in this section are as follows:

•Route Reflector 1 Configuration Example (Non MPLS VPN Service Provider)

•ASBR1 Configuration Example (Non MPLS VPN Service Provider)

•Route Reflector 2 Configuration Example (Non MPLS VPN Service Provider)

•ASBR2 Configuration Example (Non MPLS VPN Service Provider)

•ASBR3 Configuration Example (Non MPLS VPN Service Provider)

•Route Reflector 3 Configuration Example (Non MPLS VPN Service Provider)

•ASBR4 Configuration Example (Non MPLS VPN Service Provider)

Figure 5 shows two MPLS VPN service providers that are connected through a non MPLS VPN service provider. The autonomous system in the middle of the network is configured as a backbone autonomous system that uses Label Distribution Protocol (LDP) or Tag Distribution Protocol (TDP) to distribute MPLS labels. You can also use traffic engineering tunnels instead of TDP or LDP to build the LSP across the non MPLS VPN service provider.

Figure 5 Distributing Routes and MPLS Labels Over a Non MPLS VPN Service Provider

Route Reflector 1 Configuration Example (Non MPLS VPN Service Provider)

The configuration example for RR1 specifies the following:

•RR1 exchanges VPNv4 routes with RR2 using multiprotocol, multihop EBGP.

•The VPNv4 next hop information and the VPN label are preserved across the autonomous systems.

•RR1 reflects to PE1:

–The VPNv4 routes learned from RR2

–The IPv4 routes and MPLS labels learned from ASBR1

ip subnet-zero

ip cef

!

interface Loopback0

 ip address aa.aa.aa.aa 255.255.255.255

 no ip directed-broadcast

!

interface Serial1/2

 ip address dd.0.0.2 255.0.0.0

 no ip directed-broadcast

 clockrate 124061

!   

router ospf 10

 log-adjacency-changes

 auto-cost reference-bandwidth 1000

 network aa.aa.aa.aa 0.0.0.0 area 100

 network dd.dd.0.0.0 0.255.255.255 area 100

!

router bgp 100

 bgp cluster-id 1

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor ee.ee.ee.ee remote-as 100

 neighbor ee.ee.ee.ee update-source Loopback0

 neighbor ww.ww.ww.ww remote-as 100

 neighbor ww.ww.ww.ww update-source Loopback0

 neighbor bb.bb.bb.bb remote-as 200

 neighbor bb.bb.bb.bb ebgp-multihop 255

 neighbor bb.bb.bb.bb update-source Loopback0

 no auto-summary

 !

address-family ipv4

 neighbor ee.ee.ee.ee activate

 neighbor ee.ee.ee.ee route-reflector-client                !IPv4+labels session to PE1

 neighbor ee.ee.ee.ee send-label

 neighbor ww.ww.ww.ww activate

 neighbor ww.ww.ww.ww route-reflector-client                !IPv4+labels session to ASBR1

 neighbor ww.ww.ww.ww send-label

 no neighbor bb.bb.bb.bb activate

 no auto-summary

 no synchronization

 exit-address-family

 !

 address-family vpnv4

 neighbor ee.ee.ee.ee activate

 neighbor ee.ee.ee.ee route-reflector-client               !VPNv4 session with PE1

 neighbor ee.ee.ee.ee send-community extended

 neighbor bb.bb.bb.bb activate             

 neighbor bb.bb.bb.bb next-hop-unchanged                    !MH-VPNv4 session with RR2

 neighbor bb.bb.bb.bb send-community extended                 with next-hop-unchanged     

 exit-address-family

!

ip default-gateway 3.3.0.1

no ip classless

!

snmp-server engineID local 00000009020000D0584B25C0

snmp-server community public RO

snmp-server community write RW

no snmp-server ifindex persist

snmp-server packetsize 2048

!

end

ASBR1 Configuration Example (Non MPLS VPN Service Provider)

ASBR1 exchanges IPv4 routes and MPLS labels with ASBR2.

In this example, ASBR1 uses route maps to filter routes.

•A route map called OUT specifies that ASBR1 should distribute the PE1 route (ee.ee) with labels and the RR1 route (aa.aa) without labels.

•A route map called IN specifies that ASBR1 should accept the PE2 route (ff.ff) with labels and the RR2 route (bb.bb) without labels.

ip subnet-zero

ip cef distributed

mpls label protocol tdp

!

interface Loopback0

 ip address ww.ww.ww.ww 255.255.255.255

 no ip directed-broadcast

 no ip route-cache

 no ip mroute-cache

!

interface Serial3/0/0

 ip address kk.0.0.2 255.0.0.0

 no ip directed-broadcast

 ip route-cache distributed

!

interface Ethernet0/3

 ip address dd.0.0.1 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

 mpls label protocol ldp

 mpls ip

!

router ospf 10

 log-adjacency-changes

 auto-cost reference-bandwidth 1000

 redistribute connected subnets

 passive-interface Serial3/0/0

 network ww.ww.ww.ww 0.0.0.0 area 100

 network dd.0.0.0 0.255.255.255 area 100

router bgp 100

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor aa.aa.aa.aa remote-as 100

 neighbor aa.aa.aa.aa update-source Loopback0

 neighbor kk.0.0.1 remote-as 200

 no auto-summary

!

 address-family ipv4

 redistribute ospf 10                      ! Redistributing IGP into BGP  

 neighbor aa.aa.aa.aa activate             ! so that PE1 & RR1 loopbacks

 neighbor aa.aa.aa.aa send-label           ! get into BGP table

 neighbor kk.0.0.1 activate

 neighbor kk.0.0.1 advertisement-interval 5

 neighbor kk.0.0.1 send-label

 neighbor kk.0.0.1 route-map IN in    ! Accepting routes specified in route map IN

 neighbor kk.0.0.1 route-map OUT out  ! Distributing routes specified in route map OUT

 no auto-summary

 no synchronization

 exit-address-family

!

ip default-gateway 3.3.0.1

ip classless

!

access-list 1 permit ee.ee.ee.ee log

access-list 2 permit ff.ff.ff.ff log

access-list 3 permit aa.aa.aa.aa log

access-list 4 permit bb.bb.bb.bb log

!

route-map IN permit 10

 match ip address 2

 match mpls-label

!

route-map IN permit 11

 match ip address 4

!

route-map OUT permit 12

 match ip address 3

!

route-map OUT permit 13

 match ip address 1

 set mpls-label

!

end

Route Reflector 2 Configuration Example (Non MPLS VPN Service Provider)

RR2 exchanges VPNv4 routes with RR1 using multihop, multiprotocol EBGP. This configuration also specifies that the next hop information and the VPN label are preserved across the autonomous systems.

ip subnet-zero

ip cef

! 

interface Loopback0

 ip address bb.bb.bb.bb 255.255.255.255

 no ip directed-broadcast

!

interface Serial1/1

 ip address ii.0.0.2 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

!

router ospf 20

 log-adjacency-changes

 network bb.bb.bb.bb 0.0.0.0 area 200

 network ii.0.0.0 0.255.255.255 area 200

!

router bgp 200

 bgp cluster-id 1

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor aa.aa.aa.aa remote-as 100

 neighbor aa.aa.aa.aa ebgp-multihop 255

 neighbor aa.aa.aa.aa update-source Loopback0

 neighbor ff.ff.ff.ff remote-as 200

 neighbor ff.ff.ff.ff update-source Loopback0

 no auto-summary

 !

 address-family vpnv4

 neighbor aa.aa.aa.aa activate

 neighbor aa.aa.aa.aa next-hop-unchanged              !MH vpnv4 session with RR1 

 neighbor aa.aa.aa.aa send-community extended              !with next-hop-unchanged

 neighbor ff.ff.ff.ff activate

 neighbor ff.ff.ff.ff route-reflector-client          !vpnv4 session with PE2

 neighbor ff.ff.ff.ff send-community extended

 exit-address-family

!

ip default-gateway 3.3.0.1

no ip classless

!

end

ASBR2 Configuration Example (Non MPLS VPN Service Provider)

ASBR2 exchanges IPv4 routes and MPLS labels with ASBR1. However, in contrast to ASBR1, ASBR2 does not use the RR to reflect IPv4 routes and MPLS labels to PE2. ASBR2 redistributes the IPv4 routes and MPLS labels learned from ASBR1 into IGP. PE2 can now reach these prefixes.

ip subnet-zero

ip cef

!

mpls label protocol tdp

!

interface Loopback0

 ip address xx.xx.xx.xx 255.255.255.255

 no ip directed-broadcast

!

interface Ethernet0/1

 ip address qq.0.0.2 255.0.0.0

 no ip directed-broadcast

!

interface Ethernet1/2

 ip address jj.0.0.1 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

 mpls label protocol tdp

 mpls ip

 !

router ospf 20

 log-adjacency-changes

 auto-cost reference-bandwidth 1000

 redistribute connected subnets

 redistribute bgp 200 subnets            !redistributing the routes learned from 

 passive-interface Ethernet0/1                !ASBR2 (EBGP+labels session) into IGP 

 network xx.xx.xx.xx 0.0.0.0 area 200         !so that PE2 will learn them  

 network jj.0.0.0 0.255.255.255 area 200

 !

router bgp 200

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor bb.bb.bb.bb remote-as 200

 neighbor bb.bb.bb.bb update-source Loopback0

 neighbor qq.0.0.1 remote-as 100

 no auto-summary

! 

address-family ipv4                          ! Redistributing IGP into BGP                                                                                 
redistribute ospf 20                         ! so that PE2 & RR2 loopbacks

 neighbor qq.0.0.1 activate                  !  will get into the BGP-4 table

 neighbor qq.0.0.1 advertisement-interval 5

 neighbor qq.0.0.1 route-map IN in

 neighbor qq.0.0.1 route-map OUT out

 neighbor qq.0.0.1 send-label

 no auto-summary

 no synchronization

 exit-address-family

 ! 

address-family vpnv4

 neighbor bb.bb.bb.bb activate

 neighbor bb.bb.bb.bb send-community extended

 exit-address-family

 !

ip default-gateway 3.3.0.1

ip classless

!

access-list 1 permit ff.ff.ff.ff log

access-list 2 permit ee.ee.ee.ee log

access-list 3 permit bb.bb.bb.bb log

access-list 4 permit aa.aa.aa.aa log

!

route-map IN permit 11

 match ip address 2

 match mpls-label

!

route-map IN permit 12

 match ip address 4

!

route-map OUT permit 10

 match ip address 1

 set mpls-label

!

route-map OUT permit 13

 match ip address 3

!

end

ASBR3 Configuration Example (Non MPLS VPN Service Provider)

ASBR3 belongs to a non MPLS VPN service provider. ASBR3 exchanges IPv4 routes and MPLS labels with ASBR1. ASBR3 also passes the routes learned from ASBR1 to ASBR3 through RR3.

---

Note Do not redistribute EBGP routes learned into IBG if you are using IBGP to distribute the routes and labels. This is not a supported configuration.

---

ip subnet-zero

ip cef

!

interface Loopback0

 ip address yy.yy.yy.yy 255.255.255.255

 no ip directed-broadcast

 no ip route-cache

 no ip mroute-cache

!

interface Hssi4/0

 ip address mm.0.0.0.1 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

 mpls ip

 hssi internal-clock

 !

interface Serial5/0

 ip address kk.0.0.1 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

 load-interval 30

 clockrate 124061

!

router ospf 30

log-adjacency-changes

auto-cost reference-bandwidth 1000

redistribute connected subnets

network yy.yy.yy.yy 0.0.0.0 area 300 

network mm.0.0.0 0.255.255.255 area 300 

!

router bgp 300

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor cc.cc.cc.cc remote-as 300

 neighbor cc.cc.cc.cc update-source Loopback0

 neighbor kk.0.0.2 remote-as 100

 no auto-summary

 !

 address-family ipv4

 neighbor cc.cc.cc.cc activate            ! IBGP+labels session with RR3

 neighbor cc.cc.cc.cc send-label

 neighbor kk.0.0.2 activate               ! EBGP+labels session with ASBR1

 neighbor kk.0.0.2 advertisement-interval 5

 neighbor kk.0.0.2 send-label

neighbor kk.0.0.2 route-map IN in 

neighbor kk.0.0.2 route-map OUT out 

no auto-summary

 no synchronization

 exit-address-family

!

ip classless 

! 

access-list 1 permit ee.ee.ee.ee log 

access-list 2 permit ff.ff.ff.ff log 

access-list 3 permit aa.aa.aa.aa log 

access-list 4 permit bb.bb.bb.bb log 

! 

route-map IN permit 10 

 match ip address 1 

  match mpls-label 

! 

route-map IN permit 11 

   match ip address 3 

! 

route-map OUT permit 12 

 match ip address 2 

  set mpls-label 

! 

route-map OUT permit 13 

   match ip address 4 

! 

ip default-gateway 3.3.0.1

ip classless

!

end

Route Reflector 3 Configuration Example (Non MPLS VPN Service Provider)

RR3 is a non MPLS VPN RR that reflects IPv4 routes with MPLS labels to ASBR3 and ASBR4.

ip subnet-zero

mpls label protocol tdp

mpls traffic-eng auto-bw timers

no mpls ip

!

interface Loopback0

 ip address cc.cc.cc.cc 255.255.255.255

 no ip directed-broadcast

!

interface POS0/2

 ip address pp.0.0.1 255.0.0.0

 no ip directed-broadcast

 no ip route-cache cef

 no ip route-cache

 no ip mroute-cache

 crc 16

 clock source internal

!

router ospf 30

 log-adjacency-changes

 network cc.cc.cc.cc 0.0.0.0 area 300

 network pp.0.0.0 0.255.255.255 area 300

!

router bgp 300

 bgp log-neighbor-changes

 neighbor zz.zz.zz.zz remote-as 300

 neighbor zz.zz.zz.zz update-source Loopback0

 neighbor yy.yy.yy.yy remote-as 300

 neighbor yy.yy.yy.yy update-source Loopback0

 no auto-summary

 !

address-family ipv4

 neighbor zz.zz.zz.zz activate

 neighbor zz.zz.zz.zz route-reflector-client   

 neighbor zz.zz.zz.zz send-label               ! IBGP+labels session with ASBR3 

 neighbor yy.yy.yy.yy activate                 

 neighbor yy.yy.yy.yy route-reflector-client

 neighbor yy.yy.yy.yy send-label               ! IBGP+labels session with ASBR4

 no auto-summary

 no synchronization

 exit-address-family

!

ip default-gateway 3.3.0.1

ip classless

!

end 

ASBR4 Configuration Example (Non MPLS VPN Service Provider)

ASBR4 belongs to a non MPLS VPN service provider. ASBR4 and ASBR3 exchange IPv4 routes and MPLS labels by means of RR3.

---

Note Do not redistribute EBGP routes learned into IBG if you are using IBGP to distribute the routes and labels. This is not a supported configuration.

---

ip subnet-zero

ip cef distributed

!

interface Loopback0

 ip address zz.zz.zz.zz 255.255.255.255

 no ip directed-broadcast

 no ip route-cache

 no ip mroute-cache

!

interface Ethernet0/2

 ip address qq.0.0.1 255.0.0.0

 no ip directed-broadcast

 no ip mroute-cache

!

interface POS1/1/0

 ip address pp.0.0.2 255.0.0.0

 no ip directed-broadcast

 ip route-cache distributed

 !

interface Hssi2/1/1

 ip address mm.0.0.2 255.0.0.0

 no ip directed-broadcast

 ip route-cache distributed

 no ip mroute-cache

 mpls label protocol tdp

 mpls ip

 hssi internal-clock

!

router ospf 30

 log-adjacency-changes

 auto-cost reference-bandwidth 1000

 redistribute connected subnets

passive-interface Ethernet0/2

 network zz.zz.zz.zz 0.0.0.0 area 300

 network pp.0.0.0 0.255.255.255 area 300

 network mm.0.0.0 0.255.255.255 area 300

 !

router bgp 300

 bgp log-neighbor-changes

 timers bgp 10 30

 neighbor cc.cc.cc.cc remote-as 300

 neighbor cc.cc.cc.cc update-source Loopback0

 neighbor qq.0.0.2 remote-as 200

 no auto-summary

 !

 address-family ipv4

 neighbor cc.cc.cc.cc activate

 neighbor cc.cc.cc.cc send-label

 neighbor qq.0.0.2 activate

 neighbor qq.0.0.2 advertisement-interval 5

 neighbor qq.0.0.2 send-label

 neighbor qq.0.0.2 route-map IN in 

 neighbor qq.0.0.2 route-map OUT out 

no auto-summary

 no synchronization

 exit-address-family

!

ip classless 

! 

access-list 1 permit ff.ff.ff.ff log 

access-list 2 permit ee.ee.ee.ee log 

access-list 3 permit bb.bb.bb.bb log 

access-list 4 permit aa.aa.aa.aa log 

! 

route-map IN permit 10 

 match ip address 1 

  match mpls-label 

! 

route-map IN permit 11 

   match ip address 3 

! 

route-map OUT permit 12 

 match ip address 2 

  set mpls-label 

! 

route-map OUT permit 13 

   match ip address 4 

!

ip default-gateway 3.3.0.1

ip classless

!

end

Additional References

The following sections provide references related to MPLS VPN—Inter-AS IPv4 BGP Label Distribution.

Related Documents

Related Topic	Document Title
MPLS VPN Interautonomous systems configuration tasks	MPLS VPN—Interautonomous System Support
VPN configuration tasks	MPLS Virtual Private Networks (VPNs)
An explanation of how BGP works and how you can use it to participate in routing with other networks that run BGP	Using the Border Gateway Protocol for Interdomain Routing
BGP configuration tasks	"Configuring BGP" chapter in the Cisco IOS IP Configuration Guide, Release 12.2
An explanation of the purpose of BGP and the BGP route selection process, and how to use BGP attributes in route selection	"Border Gateway Protocol" chapter in the Internetworking Technology Overview
MPLS configuration tasks	"Configuring Multiprotocol Label Switching" chapter in the Cisco IOS Switching Services Configuration Guide, Release 12.2
Commands to configure and monitor BGP	"BGP Commands" chapter in the Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols, Release 12.2
Explicit null labels	MPLS VPN—Explicit Null Label Support with BGP IPv4 Label Session

Standards

Standards	Title
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.	—

MIBs

MIBs	MIBs Link
No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.	To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

RFCs

RFCs	Title
RFC 1700	Assigned Numbers
RFC 1966	BGP Route Reflection: An Alternative to Full Mesh IBGP
RFC 2842	Capabilities Advertisement with BGP-4
RFC 2858	Multiprotocol Extensions for BGP-4
RFC 3107	Carrying Label Information in BGP-4

Technical Assistance

Description	Link
Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.	http://www.cisco.com/public/support/tac/home.shtml

Command Reference

None.

Glossary

AS—autonomous system. A collection of networks that share the same routing protocol and that are under the same system administration.

ASBR—autonomous system boundary router. A router that connects and exchanges information between two or more autonomous systems.

BGP—Border Gateway Protocol. The exterior border gateway protocol used to exchange routing information between routers in separate autonomous systems. BGP uses Transmission Control Protocol (TCP). Because TCP is a reliable protocol, BGP does not experience problems with dropped or fragmented data packets.

CE router—customer edge router. The customer router that connects to the provider edge (PE) router.

EBGP—External Border Gateway Protocol. A BGP session between routers in different autonomous systems (ASs). When a pair of routers in different ASs are more than one IP hop away from each other, an EBGP session between those two routers is called multihop EBGP.

IBGP—Internal Border Gateway Protocol. A BGP session between routers within the same autonomous system.

IGP—Interior Gateway Protocol. Internet protocol used to exchange routing information within an autonomous system. Examples of common Internet IGPs include Interior Gateway Routing Protocol (IGRP), Open Shortest Path First (OSPF), and Routing Information Protocol (RIP).

LDP—Label Distribution Protocol. A standard protocol between MPLS-enabled routers to negotiate the labels (addresses) used to forward packets. This protocol is not supported in Cisco IOS Release 12.0. The Cisco proprietary version of this protocol is the Tag Distribution Protocol (TDP).

LER—label edge router. The edge router that performs label imposition and disposition.

LSR—label switch router. The role of an LSR is to forward packets in an MPLS network by looking only at the fixed-length label.

NLRI—Network Layer Reachability Information. BGP sends routing update messages containing NLRI, which describes the route. In this context, an NLRI is a prefix. A BGP update message carries one or more NLRI prefixes and the attributes of a route for the NLRI prefixes. The route attributes include a BGP next hop gateway address, community values, and other information.

P router—provider router. The core router in the service provider network that connects to provider edge (PE) routers. In a packet-switched star topology, a router that is part of the backbone and that serves as the single pipe through which all traffic from peripheral networks must pass on its way to other peripheral networks.

PE router—provider edge router. The label edge router (LER) in the service provider network that connects to the customer edge (CE) router.

RR—route reflector. A router that advertises or reflects IBGP learned routes to other IBGP peers without requiring a full network mesh.

VPN—Virtual Private Network. A group of sites that, as a result of a set of administrative policies, can communicate with each other over a shared backbone.

VPNv4 addresses—When multiple VPNs use the same address space, the VPN addresses are made unique by adding a route distinguisher to the front of the address.

---

Note Refer to the Internetworking Terms and Acronyms for terms not included in this glossary.

---

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