MPLS Traffic Engineering-Autotunnel Primary and Backup
First Published: January 26, 2004
Last Updated: November 24, 2010
The MPLS Traffic Engineering-Autotunnel Primary and Backup feature enables a router to dynamically build backup tunnels and to dynamically create one-hop primary tunnels on all interfaces that have been configured with Multiprotocol Label Switching (MPLS) traffic engineering (TE) tunnels.
A router with primary one-hop autotunnels and backup autotunnels can be configured with stateful switchover (SSO) redundancy.
Finding Feature Information
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Contents
•Prerequisites for MPLS Traffic Engineering-Autotunnel Primary and Backup
•Restrictions for MPLS Traffic Engineering-Autotunnel Primary and Backup
•Information About MPLS Traffic Engineering-Autotunnel Primary and Backup
•How to Configure MPLS Traffic Engineering Autotunnel Primary and Backup
•Configuration Examples for MPLS Traffic Engineering-Autotunnel Primary and Backup
•Additional References
•Feature Information for MPLS Traffic Engineering-Autotunnel Primary and Backup
•Glossary
Prerequisites for MPLS Traffic Engineering-Autotunnel Primary and Backup
•Configure TE on the routers.
Restrictions for MPLS Traffic Engineering-Autotunnel Primary and Backup
•You cannot configure a static route to route traffic over TE autotunnels. For autotunnels, you should use only the autoroute for tunnel selection.
Information About MPLS Traffic Engineering-Autotunnel Primary and Backup
To configure autotunnels, you need to understand the following concepts:
•Overview of MPLS Traffic Engineering-Autotunnel Primary and Backup
•Benefits of MPLS Traffic Engineering-Autotunnel Primary and Backup Feature
•MPLS Traffic Engineering
•MPLS Traffic Engineering Backup Autotunnels
•MPLS Traffic Engineering Primary Autotunnels
•MPLS Traffic Engineering Label-Based Forwarding
•Benefits of MPLS Traffic Engineering Protection
•SSO Redundancy Overview
Overview of MPLS Traffic Engineering-Autotunnel Primary and Backup
The MPLS Traffic Engineering-Autotunnel Primary and Backup feature has the following features:
•Backup autotunnel-Enables a router to dynamically build backup tunnels.
•Primary one-hop autotunnel-Enables a router to dynamically create one-hop primary tunnels on all interfaces that have been configured with MPLS TE tunnels.
If no backup tunnels exist, the following types of backup tunnels are created:
•Next hop (NHOP)
•Next-next hop (NNHOP)
Benefits of MPLS Traffic Engineering-Autotunnel Primary and Backup Feature
•Backup tunnels are built automatically, eliminating the need for users to preconfigure each backup tunnel and then assign the backup tunnel to the protected interface.
•The dynamic creation of one-hop primary tunnels eliminates the need to configure an MPLS TE tunnel with the Fast Reroute (FRR) option for the tunnel to be protected.
•Protection is expanded; FRR does not protect IP traffic that is not using the TE tunnel or Label Distribution Protocol (LDP) labels that are not using the TE tunnel.
MPLS Traffic Engineering
MPLS is an Internet Engineering Task Force (IETF)-specified framework that provides for the efficient designation, routing, forwarding, and switching of traffic flows through the network.
TE is the process of adjusting bandwidth allocations to ensure that enough bandwidth is left for high-priority traffic.
In MPLS TE, the upstream router creates a network tunnel for a particular traffic stream, then sets the bandwidth available for that tunnel.
MPLS Traffic Engineering Backup Autotunnels
MPLS backup autotunnels protect fast reroutable TE label switched paths (LSPs). Without MPLS backup autotunnels to protect a LSP you had to do the following:
•Preconfigure each backup tunnel.
•Assign the backup tunnels to the protected interfaces.
An LSP requests backup protection from Resource Reservation Protocol (RSVP) FRR in the following situations:
•Receipt of the first RSVP Resv message
•Receipt of an RSVP path message with the protection attribute after the LSP has been established without the protection attribute
•Detection that a Record Route Object (RRO) changed
If there was no backup tunnel protecting the interface used by the LSP, the LSP remained unprotected.
Backup autotunnels enable a router to dynamically build backup tunnels when they are needed. This prevents you from having to build MPLS TE tunnels statically.
Backup tunnels may not be available for the following reasons:
•Static backup tunnels are not configured.
•Static backup tunnels are configured, but cannot protect the LSP. The backup tunnel may not have enough available bandwidth, the tunnel may protect a different pool, or the tunnel may be down.
If a backup tunnel is not available, the following two backup tunnels are created dynamically:
•NHOP—Protects against link failure
•NNHOP—Protects against node failure
Note At the penultimate hop, only an NHOP backup tunnel is created.
Note If two LSPs share the same output interface and NHOP, three (not four) backup tunnels are created. They share an NHOP backup tunnel.
Link Protection
Backup tunnels that bypass only a single link of the LSP's path provide link protection. They protect LSPs if a link along their path fails by rerouting the LSP's traffic to the next hop (bypassing the failed link). These are referred to as NHOP backup tunnels because they terminate at the LSP's next hop beyond the point of failure. Figure 1 illustrates an NHOP backup tunnel.
Figure 1 Next-Hop Backup Tunnel
Node Protection
Backup tunnels that bypass next-hop nodes along LSP paths are called NNHOP backup tunnels because they terminate at the node following the next-hop node of the LSPs, thereby bypassing the next-hop node. They protect LSPs by enabling the node upstream of a link or node failure to reroute the LSPs and their traffic around the failure to the next-hop node. NNHOP backup tunnels also provide protection from link failures because they bypass the failed link and the node.
Figure 2 illustrates an NNHOP backup tunnel.
Figure 2 Next-Next Hop Backup Tunnel
Explicit Paths
Explicit paths are used to create backup autotunnels as follows:
•NHOP excludes the protected link's IP address.
•NNHOP excludes the NHOP router ID.
•The explicit-path name is _auto-tunnel_tunnelxxx, where xxx matches the dynamically created backup tunnel ID.
•The interface used for the ip unnumbered command defaults to Loopback0. You can configure this to use a different interface.
Range for Backup Autotunnels
The tunnel range for backup autotunnels is configurable. By default, the last 100 TE tunnel IDs are used; that is 65,436 to 65,535. Autotunnels detect tunnel IDs that are being used. IDs are allocated starting with the lowest number.
For example, if you configure a tunnel range 1000 to 1100 and statically configured TE tunnels are in that range, routers do not use those IDs. If those static tunnels are removed, the MPLS TE dynamic tunnel software can use those IDs.
MPLS Traffic Engineering Primary Autotunnels
The MPLS Traffic Engineering-Autotunnel Primary and Backup feature enables a router to dynamically create one-hop primary tunnels on all interfaces that have been configured with MPLS traffic. The tunnels are created with zero bandwidth. The constraint-based shortest path first (CSPF) is the same as the shortest path first (SPF) when there is zero bandwidth, so the router's choice of the autorouted one-hop primary tunnel is the same as if there were no tunnel. Because it is a one-hop tunnel, the encapsulation is tag-implicit (that is, there is no tag header).
Explicit Paths
Explicit paths are used to create autotunnels as follows:
•The explicit path is dynamically created.
•The explicit path includes the IP address for the interface connected to the next hop.
•The explicit-path name is _auto-tunnel_tunnelxxx, where xxx matches the dynamically created one-hop tunnel ID.
•Interfaces used for the ip unnumbered command default to Loopback0. You can configure this to use a different interface.
Range for Autotunnels
The tunnel range is configurable. By default, the last 100 TE tunnel IDs are used; that is 65,436 to 65,535. Autotunnels detect tunnel IDs that are being used. IDs are allocated starting with the lowest number.
For example, if you configure a tunnel range 100 to 200 and statically configured TE tunnels are in that range, routers do not use those IDs. If those static tunnels are removed, the IDs become available for use by the MPLS TE dynamic tunnel software.
MPLS Traffic Engineering Label-Based Forwarding
Routers receive a packet, determine where it needs to go by examining some fields in the packet, and send it to the appropriate output device. A label is a short, fixed-length identifier that is used to forward packets. A label switching device normally replaces the label in a packet with a new value before forwarding the packet to the next hop. For this reason, the forwarding algorithm is called label swapping. A label switching device, referred to as an LSR, runs standard IP control protocols (that is, routing protocols, RSVP, and so forth) to determine where to forward packets.
Benefits of MPLS Traffic Engineering Protection
The following sections describe the benefits of MPLS traffic engineering protection:
•Delivery of Packets During a Failure
•Multiple Backup Tunnels Protecting the Same Interface
•Scalability
•RSVP Hello
Delivery of Packets During a Failure
Backup tunnels that terminate at the NNHOP protect both the downstream link and node. This provides protection for link and node failures.
Multiple Backup Tunnels Protecting the Same Interface
In addition to being required for node protection, the autotunnel primary and backup feature provides the following benefits:
•Redundancy—If one backup tunnel is down, other backup tunnels protect LSPs.
•Increased backup capacity—If the protected interface is a high-capacity link and no single backup path exists with an equal capacity, multiple backup tunnels can protect that one high-capacity link. The LSPs using this link will fail over to different backup tunnels, allowing all of the LSPs to have adequate bandwidth protection during failure (rerouting). If bandwidth protection is not desired, the router spreads LSPs across all available backup tunnels (that is, there is load balancing across backup tunnels).
Scalability
A backup tunnel can protect multiple LSPs. Furthermore, a backup tunnel can protect multiple interfaces. This is called many-to-one (N:1) protection. N:1 protection has significant scalability advantages over one-to-one (1:1) protection, where a separate backup tunnel must be used for each LSP needing protection.
An example of N:1 protection is that when one backup tunnel protects 5000 LSPs, each router along the backup path maintains one additional tunnel.
An example of 1:1 protection is that when 5000 backup tunnels protect 5000 LSPs, each router along the backup path must maintain state for an additional 5000 tunnels.
RSVP Hello
RSVP Hello allows a router to detect when its neighbor has gone down but its interface to that neighbor is still operational. When Layer 2 link protocols are unable to detect that the neighbor is unreachable, Hellos provide the detection mechanism; this allows the router to switch LSPs onto its backup tunnels and avoid packet loss.
SSO Redundancy Overview
The SSO feature is an incremental step within an overall program to improve the availability of networks constructed with Cisco IOS routers.
SSO is particularly useful at the network edge. It provides protection for network edge devices with dual route processors (RPs) that represent a single point of failure in the network design, and where an outage might result in loss of service for customers.
In specific Cisco networking devices that support dual RPs, SSO takes advantage of RP redundancy to increase network availability. The feature establishes one of the RPs as the active processor while the other RP is designated as the standby processor, and then synchronizes critical state information between them. Following an initial synchronization between the two processors, SSO dynamically maintains RP state information between them.
A switchover from the active to the standby processor occurs when the active RP fails, is removed from the networking device, or is manually taken down for maintenance.
Affinity and Link Attributes with Autotunnel Backup
In Cisco IOS Release 15.1(1)S and later releases, you can use affinity and link attributes with the MPLS TE Autotunnel Backup feature to include or exclude links when configuring dynamic backup paths.
For a link, you can configure up to 32 bits of attribute flags, as shown in the following example:
Router# configure terminal
Router(config)# interface ethernet0/0
Router(config-if)# mpls traffic-eng attribute-flags 0x22
The attribute flags are compared to the tunnel's affinity bits during selection of the path.
When you enable the auto-tunnel backup feature, you can optionally specify the affinity and mask, as shown in the following example. If you do not specify an affinity and mask, the default for affinity is 0 and for the mask it is 0xFFFF is used. To ignore link affinity, use affinity and mask of 0. See the mpls traffic-eng auto-tunnel backup config affinity command for more information.
Router# configure terminal
Router(config)# mpls traffic-eng auto-tunnel backup
Router(config)# mpls traffic-eng auto-tunnel backup config affinity 0x13 mask 0x13
The affinity/mask configured by the mpls traffic-eng auto-tunnel backup config affinity command is used for all dynamically created backup tunnels. The attribute mask determines which link attributes are relevent. If a bit in the mask is 0, the attribute is irrelevant. If a bit in the mask is 1, the attribute value of a link and the configured affinity of the tunnel for that bit must match.
In Figure 3, there are two primary tunnels. One tunnel travels from router A to router B. The other primary tunnel travels from router A to router B and then router D. All the the links are configured with attribute flags 0x22. Both tunnels require fast reroute protection. To automatically create backup tunnels, enable the autotunnel backup feature with the mpls traffic-eng auto-tunnel backup command. However, the dynamically created backup tunnels do not come up, because attribute flags are configured on the links. To enable the dynamically created backup tunnels, you must also issue the following command:
Router(config)# mpls traffic-eng auto-tunnel backup config affinity 0x22 mask 0x22
Figure 3 Specifying Link Attributes and Affinity with Autotunnel Backup
How to Configure MPLS Traffic Engineering Autotunnel Primary and Backup
This sections contains the following procedures:
•Establishing MPLS Backup Autotunnels to Protect Fast Reroutable TE LSPs (required)
•Establishing MPLS One-Hop Tunnels to All Neighbors (required)
Establishing MPLS Backup Autotunnels to Protect Fast Reroutable TE LSPs
To establish an MPLS backup autotunnel to protect fast reroutable TE LSPs, perform the following task.
Note Only Steps 1 through 3 are required. If you perform additional steps, you can perform them in any order after Step 3.
SUMMARY STEPS
1. enable
2. configure terminal
3. mpls traffic-eng auto-tunnel backup
4. mpls traffic-eng auto-tunnel backup nhop-only
5. mpls traffic-eng auto-tunnel backup tunnel-num [min num] [max num]
6. mpls traffic-eng auto-tunnel backup timers removal unused sec
7. mpls traffic-eng auto-tunnel backup config unnumbered-interface interface
8. mpls traffic-eng auto-tunnel backup config affinity affinity-value [mask mask-value]
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Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
mpls traffic-eng auto-tunnel backup
Router(config)# mpls traffic-eng auto-tunnel backup |
Automatically builds NHOP and NNHOP backup tunnels. |
Step 4 |
mpls traffic-eng auto-tunnel backup nhop-only
Router(config)# mpls traffic-eng auto-tunnel backup nhop-only |
Enables the creation of dynamic NHOP backup tunnels. |
Step 5 |
mpls traffic-eng auto-tunnel backup tunnel-num [min num] [max num]
Router(config)# mpls traffic-eng auto-tunnel backup tunnel-num min 1000 max 1100 |
Configures the range of tunnel interface numbers for backup autotunnels. |
Step 6 |
mpls traffic-eng auto-tunnel backup timers removal unused sec
Router(config)# mpls traffic-eng auto-tunnel backup timers removal unused 50 |
Configures how frequently a timer will scan backup autotunnels and remove tunnels that are not being used. |
Step 7 |
mpls traffic-eng auto-tunnel backup config unnumbered-interface interface
Router(config)# mpls traffic-eng auto-tunnel backup config unnumbered-interface ethernet1/0 |
Enables IP processing on the specified interface without an explicit address. |
Step 8 |
mpls traffic-eng auto-tunnel backup config affinity affinity-value [mask mask-value]
Router(config)# mpls traffic-eng auto-tunnel backup config affinity 0x22 mask 0x22 |
Specifies the affinity values and mask flags. The affinity determines the attribute of the link that the tunnel will use. That is, the attribute for which the tunnel has an affinity. The mask determines which link attribute the router should check. If a bit in the mask is 0, an attribute value of a link or that bit is irrelevant. If a bit in the mask is 1, the attribute values of a link and the required affinity of the tunnel for that bit must match. |
Establishing MPLS One-Hop Tunnels to All Neighbors
To establish MPLS one-hop tunnels to all neighbors, perform the following task.
Note Only Steps 1 through 3 are required. If you perform additional steps, you can perform them in any order after Step 3.
SUMMARY STEPS
1. enable
2. configure terminal
3. mpls traffic-eng auto-tunnel primary onehop
4. mpls traffic-eng auto-tunnel primary tunnel-num [min num] [max num]
5. mpls traffic-eng auto-tunnel primary timers removal rerouted sec
6. mpls traffic-eng auto-tunnel primary config unnumbered interface
7. mpls traffic-eng auto-tunnel primary config mpls ip
8. clear mpls traffic-eng auto-tunnel primary
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Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
mpls traffic-eng auto-tunnel primary onehop
Router(config)# mpls traffic-eng auto-tunnel primary onehop |
Automatically creates primary tunnels to all next hops. |
Step 4 |
mpls traffic-eng auto-tunnel primary tunnel-num [min num] [max num]
Router(config)# mpls traffic-eng auto-tunnel primary tunnel-num min 2000 max 2100 |
Configures the range of tunnel interface numbers for primary autotunnels. |
Step 5 |
mpls traffic-eng auto-tunnel primary timers removal rerouted sec
Router(config)# mpls traffic-eng auto-tunnel primary timers removal rerouted 400 |
Configures how many seconds after a failure primary autotunnels will be removed. |
Step 6 |
mpls traffic-eng auto-tunnel primary config unnumbered interface
Router(config)# mpls traffic-eng auto-tunnel primary config unnumbered ethernet1/0 |
Enables IP processing on the specified interface without an explicit address. |
Step 7 |
mpls traffic-eng auto-tunnel primary config mpls ip
Router(config)# mpls traffic-eng auto-tunnel primary config mpls ip |
Enables LDP on primary autotunnels. |
Step 8 |
clear mpls traffic-eng auto-tunnel primary
Router(config)# clear mpls traffic-eng auto-tunnel primary |
Removes all primary autotunnels and re-creates them. |
Configuration Examples for MPLS Traffic Engineering-Autotunnel Primary and Backup
This section contains the following configuration examples:
•Establishing MPLS Backup Autotunnels to Protect Fast Reroutable TE LSPs: Example
•Establishing MPLS One-Hop Tunnels to Neighbors: Example
Establishing MPLS Backup Autotunnels to Protect Fast Reroutable TE LSPs: Example
Note This example does not include the mpls traffic-eng auto-tunnel backup nhop-only command because autotunneling would not be able to create any backup tunnels.
To determine if there are any backup tunnels, enter the show ip rsvp fast-reroute command. This example shows that there is a static configured primary tunnel and no backup tunnels.
Router(config)# show ip rsvp fast-reroute
Primary Protect BW Backup
Tunnel I/F BPS:Type Tunnel:Label State Level Type
------ ------- ------- ------------ ------ ----- ----
R3-PRP_t0 PO3/1 0:G None None None
The following command causes autotunnels to automatically configure NHOP and NNHOP backup tunnels:
Router(config)# mpls traffic-eng auto-tunnel backup
As illustrated in the show ip interface brief command output, autotunneling created two backup tunnels that have tunnel IDs 65436 and 65437:
Router# show ip interface brief
Interface IP-Address OK? Method Status Protocol
POS2/0 10.0.0.14 YES NVRAM down down
POS2/1 10.0.0.49 YES NVRAM up up
POS2/2 10.0.0.45 YES NVRAM up up
POS2/3 10.0.0.57 YES NVRAM administratively down down
POS3/0 10.0.0.18 YES NVRAM down down
POS3/1 10.0.0.33 YES NVRAM up up
POS3/2 unassigned YES NVRAM administratively down down
POS3/3 unassigned YES NVRAM administratively down down
GigabitEthernet4/0 10.0.0.37 YES NVRAM up up
GigabitEthernet4/1 unassigned YES NVRAM administratively down down
GigabitEthernet4/2 unassigned YES NVRAM administratively down down
Loopback0 10.0.3.1 YES NVRAM up up
Tunnel0 10.0.3.1 YES unset up up
Tunnel65436 10.0.3.1 YES unset up up
Tunnel65437 10.0.3.1 YES unset up up
Ethernet0 10.3.38.3 YES NVRAM up up
Ethernet1 unassigned YES NVRAM administratively down down
The following command prevents autotunneling from creating NNHOP backup tunnels:
Router# mpls traffic-eng auto-tunnel backup nhop-only
The "Type" field in the following show ip rsvp fast-reroute command shows that there is only an NHOP tunnel:
Router# show ip rsvp fast-reroute
Primary Protect BW Backup
Tunnel I/F BPS:Type Tunnel:Label State Level Type
------ ------- -------- ------------- ------ ------- ----
R3-PRP_t0 PO3/1 0:G Tu65436:24 Ready any-unl Nhop
The following command changes the minimum and maximum tunnel interface numbers to 1000 and 1100, respectively:
Router# mpls traffic-eng auto-tunnel backup tunnel-num min 1000 max 1100
You can verify the ID numbers and autotunnel backup range ID by entering the show ip rsvp fast-reroute and show ip interface brief commands. In this example, only one backup tunnel is protecting the primary tunnel:
Router# show ip rsvp fast-reroute
Primary Protect BW Backup
Tunnel I/F BPS:Type Tunnel:Label State Level Type
------ ------- -------- ------------- ------ ----- ------
R3-PRP_t0 PO3/1 0:G Tu1000:24 Ready any-unl Nhop
Router# show ip interface brief
Interface IP-Address OK? Method Status Protocol
POS2/0 10.0.0.14 YES NVRAM down down
POS2/1 10.0.0.49 YES NVRAM up up
POS2/2 10.0.0.45 YES NVRAM up up
POS2/3 10.0.0.57 YES NVRAM administratively down down
POS3/0 10.0.0.18 YES NVRAM down down
POS3/1 10.0.0.33 YES NVRAM up up
POS3/2 unassigned YES NVRAM administratively down down
POS3/3 unassigned YES NVRAM administratively down down
GigabitEthernet4/0 10.0.0.37 YES NVRAM up up
GigabitEthernet4/1 unassigned YES NVRAM administratively down down
GigabitEthernet4/2 unassigned YES NVRAM administratively down down
Loopback0 10.0.3.1 YES NVRAM up up
Tunnel0 10.0.3.1 YES unset up up
Tunnel65436 10.0.3.1 YES unset up up
Ethernet0 10.3.38.3 YES NVRAM up up
Ethernet1 unassigned YES NVRAM administratively down down
The default tunnel range for autotunnel backup tunnels is 65,436 through 65,535. The following show ip rsvp fast-reroute command changes the tunnel range IDs:
Router# show ip rsvp fast-reroute
Primary Protect BW Backup
Tunnel I/F BPS:Type Tunnel:Label State Level Type
------ ------- -------- ------------- ------ ----- ------
R3-PRP_t0 PO3/1 0:G Tu1001:0 Ready any-unl N-Nhop
The results are shown in the show ip interface brief command:
Router# show ip interface
Router# show ip interface brief
Interface UP-Address OK? Method Status Protocol
POS2/0 10.0.0.14 YES NVRAM down down
POS2/1 10.0.0.49 YES NVRAM up up
POS2/2 10.0.0.45 YES NVRAM up up
POS2/3 10.0.0.57 YES NVRAM up up
POS3/0 10.0.0.18 YES NVRAM up up
POS3/1 10.0.0.33 YES NVRAM up up
POS3/2 unassigned YES NVRAM administratively down down
POS3/3 unassigned YES NVRAM administratively down down
Loopback0 10.0.3.1 YES NVRAM up up
Tunnel0 10.0.3.1 YES unset up up
Tunnel1000 10.0.3.1 YES unset up up
Tunnel1001 10.0.3.1 YES unset up up
Ethernet0 10.3.38.3 YES NVRAM up up
Ethernet1 unassigned YES NVRAM administratively down down
The following mpls traffic-eng auto-tunnel backup timers removal unused command specifies that a timer will scan backup autotunnels every 50 seconds and the timer will remove tunnels that are not being used:
Router(config)# mpls traffic-eng auto-tunnel backup timers removal unused 50
The following mpls traffic-eng auto-tunnel backup config unnumbered-interface command enables IP processing on POS interface 3/1:
Router(config)# mpls traffic-eng auto-tunnel backup config unnumbered-interface POS3/1
To verify that IP processing is enabled on POS3/1, enter the show interfaces tunnel command:
Router# show interfaces tunnel 1001
Tunnel1001 is up, line protocol is up
Interface is unnumbered. Using address of POS3/1 (10.0.0.33)
MTU 1514 bytes, BW 9 Kbit, DLY 500000 usec, rely 255/255, load 1/255
Encapsulation TUNNEL, loopback not set
Tunnel source 10.0.0.0, destination 10.0.5.1
Tunnel protocol/transport Label Switching, sequencing disabled
Checksumming of packets disabled
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Output queue 0/0, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
The following mpls traffic-eng auto-tunnel backup config affinity command specifies affinity and link attributes that help in the calculation of the dynamically created backup tunnel:
Router(config)# mpls traffic-eng auto-tunnel backup config affinity 0x22 mask 0x22
To display the affinity and link attributes assigned to a dynamically created backup tunnel, enter the show mpls traffic-eng auto-tunnel backup command:
Router# show mpls traffic-eng auto-tunnel backup
Tunnel Count: 3 (up:2, down: 1)
Tunnel ID Range: 65436-65535
Delete unused tunnels after: 50 Seconds
Establishing MPLS One-Hop Tunnels to Neighbors: Example
For autotunneling to automatically create primary tunnels to all next hops, you must enter the following command:
Router(config)# mpls traffic-eng auto-tunnel primary onehop
In this example there are four primary tunnels and no backup tunnels. To verify that configuration, enter the show ip rsvp fast-reroute command and the show ip interface brief command:
Router# show ip rsvp fast-reroute
Primary Protect BW Backup
Tunnel I/F BPS:Type Tunnel:Label State Level Type
------ ------- -------- ------------- ------ ----- ------
R3-PRP_t65337 PO2/2 0:G None None None
R3-PRP_t65338 PO3/1 0:G None None None
R3-PRP_t65339 Gi4/0 0:G None None None
R3-PRP_t65336 PO2/1 0:G None None None
Router# show ip interface brief
Interface IP-Address OK? Method Status Protocol
POS2/0 10.0.0.14 YES NVRAM down down
POS2/1 10.0.0.49 YES NVRAM up up
POS2/2 10.0.0.45 YES NVRAM up up
POS2/3 10.0.0.57 YES NVRAM administratively down down
POS3/0 10.0.0.18 YES NVRAM down down
POS3/1 10.0.0.33 YES NVRAM up up
POS3/2 unassigned YES NVRAM administratively down down
POS3/3 unassigned YES NVRAM administratively down down
GigabitEthernet4/0 10.0.0.37 YES NVRAM up up
GigabitEthernet4/1 unassigned YES NVRAM administratively down down
GigabitEthernet4/2 unassigned YES NVRAM administratively down down
Loopback0 10.0.3.1 YES NVRAM up up
Tunnel0 10.0.3.1 YES unset administratively down down
Tunnel65336 10.0.3.1 YES unset up up
Tunnel65337 10.0.3.1 YES unset up up
Tunnel65338 10.0.3.1 YES unset up up
Tunnel65339 10.0.3.1 YES unset up up
Ethernet0 10.3.38.3 YES NVRAM up up
Ethernet1 unassigned YES NVRAM administratively down down
The default tunnel range for primary autotunnels is 65,336 through 65,435. The following mpls traffic-eng auto-tunnel primary tunnel-num command changes the range to 2000 through 2100:
Router(config)# mpls traffic-eng auto-tunnel primary tunnel-num min 2000 max 2100
The following sample output from the show ip rsvp fast-reroute command and the show ip interface brief command shows that the tunnel IDs are 2000, 2001, 2002, and 2003:
Router# show ip rsvp fast-reroute
Primary Protect BW Backup
Tunnel I/F BPS:Type Tunnel:Label State Level Type
------ ------- -------- ------------- ------ ----- ------
R3-PRP_t2001 PO2/2 0:G None None None
R3-PRP_t2002 PO3/1 0:G None None None
R3-PRP_t2003 Gi4/0 0:G None None None
R3-PRP_t2000 PO2/1 0:G None None None
Router# show ip interface brief
Interface IP-Address OK? Method Status Protocol
POS2/0 10.0.0.14 YES NVRAM down down
POS2/1 10.0.0.49 YES NVRAM up up
POS2/2 10.0.0.45 YES NVRAM up up
POS2/3 10.0.0.57 YES NVRAM administratively down down
POS3/0 10.0.0.18 YES NVRAM down down
POS3/1 10.0.0.33 YES NVRAM up up
POS3/2 unassigned YES NVRAM administratively down down
POS3/3 unassigned YES NVRAM administratively down down
GigabitEthernet4/0 10.0.0.37 YES NVRAM up up
GigabitEthernet4/1 unassigned YES NVRAM administratively down down
GigabitEthernet4/2 unassigned YES NVRAM administratively down down
Loopback0 10.0.3.1 YES NVRAM up up
Tunnel0 10.0.3.1 YES unset administratively down down
Tunnel2000 10.0.3.1 YES unset up up
Tunnel2001 10.0.3.1 YES unset up up
Tunnel2002 10.0.3.1 YES unset up up
Tunnel2003 10.0.3.1 YES unset up up
Ethernet0 10.3.38.3 ' YES NVRAM up up
Ethernet1 unassigned YES NVRAM administratively down down
The following mpls traffic-eng auto-tunnel primary timers command specifies that a timer will scan backup autotunnels every 50 seconds and remove tunnels that are not being used:
Router(config)# mpls traffic-eng auto-tunnel primary timers removal rerouted 50
The following mpls traffic-eng auto-tunnel primary config unnumbered command enables IP processing on POS interface 3/1:
Router(config)# mpls traffic-eng auto-tunnel primary config unnumbered POS3/1
To specify that autotunneling remove all primary autotunnels and re-create them, enter the following command:
Router(config)# clear mpls traffic-eng auto-tunnel primary
Additional References
The following sections provide references related to the MPLS Traffic Engineering-Autotunnel Primary and Backup feature.
Additional References
Standards
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No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
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MIBs
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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
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No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
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Technical Assistance
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The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
http://www.cisco.com/techsupport |
Feature Information for MPLS Traffic Engineering-Autotunnel Primary and Backup
Table 1 lists the release history for this feature.
Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.
Table 1 Feature Information for MPLS Traffic Engineering-Autotunnel Primary and Backup
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Feature Configuration Information
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MPLS Traffic Engineering-Autotunnel Primary and Backup |
12.0(27)S 12.2(33)SRA 12.2(33)SXH 12.4(20)T 12.2(33)SRE 15.1(1)S |
The MPLS Traffic Engineering-Autotunnel Primary and Backup feature enables a router to dynamically build backup tunnels and to dynamically create one-hop primary tunnels on all interfaces that have been configured with MPLS TE tunnels. In Cisco IOS Release 12.0(27)S, this feature was introduced. In Cisco IOS Release 12.2(33)SRA, this feature was integrated. In Cisco IOS Release 12.2(33)SXH, support was added. In Cisco IOS Release 12.4(20)T, this feature was integrated. In Cisco IOS Release 12.2(33)SRE. this feature was integrated. A router with primary one-hop autotunnels and backup autotunnels can be configured with SSO redundancy. In Cisco IOS Release 15.1(1)S, this feture was updated to allow you to specify affinity/mask for dynamically created MPLS TE backup tunnels. The following commands were introduced: mpls traffic-eng auto-tunnel backup config affinity and show mpls traffic-eng auto-tunnel backup. |
Glossary
backup tunnel—An MPLS traffic engineering tunnel used to protect other (primary) tunnel's traffic when a link or node failure occurs.
egress router—A router at the edge of the network where packets are leaving.
Fast Reroute—Fast Reroute (FRR) is a mechanism for protecting MPLS traffic engineering (TE) LSPs from link and node failure by locally repairing the LSPs at the point of failure, allowing data to continue to flow on them while their headend routers attempt to establish end-to-end LSPs to replace them. FRR locally repairs the protected LSPs by rerouting them over backup tunnels that bypass failed links or nodes.
hop—Passage of a data packet between two network nodes (for example, between two routers).
interface—A network connection.
IP address—A 32-bit address assigned to hosts using TCP/IP. An IP address belongs to one of five classes (A, B, C, D, or E) and is written as four octets separated by periods (dotted decimal format). Each address consists of a network number, an optional subnetwork number, and a host number. The network and subnetwork numbers together are used for routing, and the host number is used to address an individual host within the network or subnetwork. A subnet mask is used to extract network and subnetwork information from the IP address.
IP explicit path—A list of IP addresses, each representing a node or link in the explicit path.
LDP—Label Distribution Protocol. A standard protocol between MPLS-enabled routers to negotiate the labels (addresses) used to forward packets.
link—Point-to-point connection between adjacent nodes.
LSP—label switched path. A path that is followed by a labeled packet over several hops, starting at an ingress LSR and ending at an egress LSR.
LSR—label switch router. A Layer 3 router that forwards a packet based on the value of a label encapsulated in the packet.
MPLS—Multiprotocol Label Switching. A method for forwarding packets (frames) through a network. It enables routers at the edge of a network to apply labels to packets. ATM switches or existing routers in the network core can switch packets according to the labels with minimal lookup overhead.
node—Endpoint of a network connection or a junction common to two or more lines in a network. Nodes can be interconnected by links, and serve as control points in the network.
penultimate router—The second-to-last router; that is, the router that is immediately before the egress router.
primary tunnel—An MPLS tunnel whose LSP can be fast rerouted if there is a failure.
router—A network layer device that uses one or more metrics to determine the optimal path along which network traffic should be forwarded. Routers forward packets from one network to another based on network layer information.
router ID—Something by which a router originating a packet can be uniquely distinguished from all other routers. For example, an IP address from one of the router's interfaces.
scalability—An indicator showing how quickly some measure of resource usage increases as a network gets larger.
traffic engineering—The techniques and processes used to cause routed traffic to travel through the network on a path other than the one that would have been chosen if standard routing methods had been used.
tunnel—A secure communication path between two peers, such as two routers. A traffic engineering tunnel is a label-switched tunnel that is used for traffic engineering. Such a tunnel is set up through means other than normal Layer 3 routing; it is used to direct traffic over a path different from the one that Layer 3 routing could cause the tunnel to take.
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Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.
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