- Finding Feature Information
- Prerequisites for Multi-VRF Selection Using Policy-Based Routing
- Restrictions for Multi-VRF Selection Using Policy-Based Routing
- Information About Multi-VRF Selection Using Policy-Based Routing
Multi-VRF Selection Using Policy-Based Routing
The Multi-VRF Selection Using Policy-Based Routing (PBR) feature allows a specified interface on a provider edge (PE) router to route packets to Virtual Private Networks (VPNs) based on packet length or match criteria defined in an IP access list.
You can enable VPN routing and forwarding (VRF) selection by policy routing packets through a route map, through the global routing table, or to a specified VRF.
You can enable policy-routing packets for VRF instances by using route map commands with set commands.
- Finding Feature Information
- Prerequisites for Multi-VRF Selection Using Policy-Based Routing
- Restrictions for Multi-VRF Selection Using Policy-Based Routing
- Information About Multi-VRF Selection Using Policy-Based Routing
- How to Configure Multi-VRF Selection Using Policy-Based Routing
- Configuration Examples for Multi-VRF Selection Using Policy-Based Routing
- Additional References
- Feature Information for Multi-VRF Selection Using Policy-Based Routing
- Glossary
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Multi-VRF Selection Using Policy-Based Routing
- The router must support policy-based routing (PBR) in order for you to configure this feature.
- A VRF must be defined before you configure this feature. An error message is displayed on the console if no VRF exists.
Restrictions for Multi-VRF Selection Using Policy-Based Routing
- All commands that aid in routing also support hardware switching, except for the set ip next-hop verify availability command because Cisco Discovery Protocol information is not available in the line cards.
- Protocol Independent Multicast (PIM) and multicast packets do not support PBR and cannot be configured for a source IP address that is a match criterion for this feature.
- The set vrf and set ip global next-hop commands can be configured with the set default interface, set interface , set ip default next-hop, and set ip next-hop commands. But the set vrf and set ip global next-hop commands take precedence over the set default interface, set interface , set ip default next-hop, and set ip next-hop commands. No error message is displayed if you attempt to configure the set vrf command with any of these three set commands.
- The Multi-VRF Selection Using Policy-Based Routing (PBR) feature cannot be configured with IP prefix lists.
- The set global and set vrf commands cannot be simultaneously applied to a route map.
- The Multi-VRF Selection Using Policy-Based Routing (PBR) feature supports VRF-lite; that is, only IP routing protocols run on the router. Multiprotocol Label Switching (MPLS) and VPN cannot be configured.
Information About Multi-VRF Selection Using Policy-Based Routing
Policy Routing of VPN Traffic Based on Match Criteria
The Multi-VRF Selection Using Policy-Based Routing feature is an extension of the VRF Selection Based on Source IP Address feature. The PBR implementation of the VRF selection feature allows you to policy route VPN traffic based on match criteria. Match criteria are defined in an IP access list and/or are based on packet length. The following match criteria are supported in Ciscosoftware:
- IP access lists--Define match criteria based on IP addresses, IP address ranges, and other IP packet access list filtering options. Named, numbered, standard, and extended access lists are supported. All IP access list configuration options in Cisco software can be used to define match criteria.
- Packet lengths--Define match criteria based on the length of a packet, in bytes. The packet length filter is defined in a route map with the match length route-map configuration command.
Policy routing is defined in the route map. The route map is applied to the incoming interface with the ip policy route-map interface configuration command. An IP access list is applied to the route map with the match ip address route-map configuration command. Packet length match criteria are applied to the route map with the match length route-map configuration command. The set action is defined with the set vrf route-map configuration command. The match criteria are evaluated, and the appropriate VRF is selected by the set command. This combination allows you to define match criteria for incoming VPN traffic and policy route VPN packets out to the appropriate VRF.
Policy-Based Routing set Commands
- Policy-routing Packets for VRF Instances
- Change of Normal Routing and Forwarding Behavior
- Support of Inherit-VRF Inter-VRF and VRF-to-Global Routing
Policy-routing Packets for VRF Instances
To enable policy-routing packets for VRF instances, you can use route map commands with the following set commands. They are listed in the order in which the router uses them during the routing of packets.
- set TOS--Sets the Type of Service (TOS) bits in the header of an IP packet.
- set DF--Sets the Don't Fragment (DF) bit in the header of an IP packet.
- set vrf--Routes packets through the specified interface. The interface can belong to the global routing table or to any other VRF instance.
- set global--Routes packets through the global routing table. This command is useful for routing ingress packets belonging to a specific VRF through the global routing table.
- set ip vrf next-hop--Indicates where to output packets that pass a match criteria of a route map for policy routing when the next hop must be under a specified VRF.
- set ip global next-hop--Indicates where to forward packets that pass a match criterion of a route map for policy routing and for which the Cisco IOS XE software uses the global routing table.
- set interface--When packets enter a VRF, routes the packets out of the egress interface under the same VRF according to the set interface policy, provided that the Layer 2 rewrite information is available.
- set ip default vrf--Provides inherit-VRF and inter-VRF routing. With inherit-VRF routing, packets arriving at a VRF interface are routed by the same outgoing VRF interface. With inter-VRF routing, packets arriving at a VRF interface are routed via any other outgoing VRF interface.
- set ip default global--Provides VRF to global routing.
- set default interface--Indicates where to output packets that pass a match criterion of a route map for policy routing and have no explicit route to the destination. The interface can belong to any VRF.
- set ip global next-hop--Routes packets through the global routing table, where the next hop lookup will be in the global routing table.
- set ip default next-hop--Indicates where to output packets that pass a match criterion of a route map for policy routing and for which the Cisco IOS XE software has no explicit route to a destination.
- set ip precedence--Sets the IP precedence bit in the header of an IP packet.
Change of Normal Routing and Forwarding Behavior
When you configure PBR, you can use the following four set commands to change normal routing and forwarding behavior. Configuring any of these set commands overrides the routing behavior of packets entering the interface if the packets do not belong to a VRF. The packets are routed from the egress interface across the global routing table.
- set default interface--Indicates where to output packets that pass a match criterion of a route map for policy routing and have no explicit route to the destination.
- set interface--When packets enter a VRF, routes the packets out of the egress interface under the same VRF according to the set interface policy, provided that the Layer 2 rewrite information is available.
Note |
The interface must be a peer-to-peer (P2P) interface. |
- set ip default next-hop--Indicates where to output packets that pass a match criterion of a route map for policy routing and for which the Cisco IOS XE software has no explicit route to a destination.
- set ip next-hop--Indicates where to output packets that pass a match criterion of a route map for policy routing.
Support of Inherit-VRF Inter-VRF and VRF-to-Global Routing
The Multi-VRF Selection Using Policy-Based Routing (PBR) feature supports inherit-VRF and inter-VRF. With inherit-VRF routing, packets arriving at a VRF interface are routed by the same outgoing VRF interface. With inter-VRF routing, packets arriving at a VRF interface are routed via any other outgoing VRF interface.
VRF-to-global routing causes packets that enter any VRF interface to be routed via the global routing table. When a packet arrives on a VRF interface, the destination lookup normally is done only in the corresponding VRF table. If a packet arrives on a global interface, the destination lookup is done in the global routing table.
The Multi-VRF Selection Using Policy-Based Routing (PBR) feature modifies the following set commands to support inherit-VRF, inter-VRF, and VRF-to-global routing. The commands are listed in the order in which the router uses them during the routing of packets.
- set global--Routes packets through the global routing table. This command is useful for routing ingress packets belonging to a specific VRF through the global routing table.
- set ip global next-hop--Indicates where to forward packets that pass a match criterion of a route map for policy routing and for which the Cisco software uses the global routing table.
- set ip vrf next-hop--Causes the router to look up the next hop in the VRF table. If a packet arrives on an interface that belongs to a VRF and the packet needs to be routed via a different VRF, you can use the set ip vrf next-hop command.
- set ip default vrf--Provides inherit-VRF and inter-VRF routing. With inherit-VRF routing, packets arriving at a VRF interface are routed by the same outgoing VRF interface. With inter-VRF routing, packets arriving at a VRF interface are routed via any other outgoing VRF interface.
- set interface--When packets enter a VRF, routes the packets out of the egress interface under the same VRF, according to the set interface policy, provided that the Layer 2 rewrite information is available.
- set default interface--Indicates where to output packets that pass a match criterion of a route map for policy routing and have no explicit route to the destination. The interface can belong to any VRF.
- set ip next-hop--Routes packets through the global routing table in an IP-to-IP routing and forwarding environment.
- set vrf--Selects the appropriate VRF after a successful match occurs in the route map. VRS-aware PSV allows only inter-VRF (or VRF-to-VRF) switching.
How to Configure Multi-VRF Selection Using Policy-Based Routing
- Defining the Match Criteria for Multi-VRF Selection Using PBR
- Configuring Multi-VRF Selection in a Route Map
- Configuring Multi-VRF Selection Using PBR and IP VRF Receive on the Interface
- Verifying the Configuration of Multi-VRF Selection Using PBR
Defining the Match Criteria for Multi-VRF Selection Using PBR
Define the match criteria for multi-VRF selection using PBR so that you can selectively route the packets instead of using their default routing and forwarding.
The match criteria for multi-VRF selection using PBR are defined in an access list. Standard, named, and extended access lists are supported.
You can define the match criteria based on the packet length by configuring the match length route-map configuration command. This configuration option is defined entirely within a route map.
The following sections explain how to configure PBR route selection:
- Configuring Multi-VRF Selection Using PBR with a Standard Access List
- Configuring Multi-VRF Selection Using PBR with a Named Extended Access List
Configuring Multi-VRF Selection Using PBR with a Standard Access List
The tasks in the following sections assume that the VRF and associated IP address are already defined.
DETAILED STEPS
Configuring Multi-VRF Selection Using PBR with a Named Extended Access List
To configure Multi-VRF Selection using PBR with a named extended access list, complete the following steps.
The tasks in the following sections assume that the VRF and associated IP address are already defined.
DETAILED STEPS
Configuring Multi-VRF Selection in a Route Map
Incoming packets are filtered through the match criteria that are defined in the route map. After a successful match occurs, the set vrf command configuration determines the VRF through which the outbound VPN packets will be policy routed.
You must define the VRF before you configure the route map; otherwise an error message appears on the console.
A receive entry must be added to the VRF selection table with the ip vrf receive command. If a match and set operation occurs in the route map but there is no receive entry in the local VRF table, the packet will be dropped if the packet destination is local.
DETAILED STEPS
Configuring Multi-VRF Selection Using PBR and IP VRF Receive on the Interface
The route map is attached to the incoming interface with the ip policy route-map interface configuration command.
The source IP address must be added to the VRF selection table. VRF selection is a one-way (unidirectional) feature. It is applied to the incoming interface. If a match and set operation occurs in the route map but there is no receive entry in the local VRF table, the packet is dropped if the packet destination is local.
DETAILED STEPS
Verifying the Configuration of Multi-VRF Selection Using PBR
To verify the configuration of the Multi-VRF Selection Using Policy-Based Routing (PBR) feature, perform the following steps. You can enter the commands in any order.
DETAILED STEPS
Configuration Examples for Multi-VRF Selection Using Policy-Based Routing
- Defining the Match Criteria for Multi-VRF Selection Using PBR Example
- Configuring Multi-VRF Selection in a Route Map Example
Defining the Match Criteria for Multi-VRF Selection Using PBR Example
In the following example, three standard access lists are created to define match criteria for three different subnetworks. Any packets received on FastEthernet interface 0/1/0 will be policy routed through the PBR-VRF-Selection route map to the VRF that is matched in the same route-map sequence. If the source IP address of the packet is part of the 10.1.0.0/24 subnet, VRF1 will be used for routing and forwarding.
access-list 40 permit source 10.1.0.0 0.0.255.255 access-list 50 permit source 10.2.0.0 0.0.255.255 access-list 60 permit source 10.3.0.0 0.0.255.255 route-map PBR-VRF-Selection permit 10 match ip address 40 set vrf VRF1 ! route-map PBR-VRF-Selection permit 20 match ip address 50 set vrf VRF2 ! route-map PBR-VRF-Selection permit 30 match ip address 60 set vrf VRF3 ! interface FastEthernet 0/1/0 ip address 192.168.1.6 255.255.255.252 ip vrf forwarding VRF4 ip policy route-map PBR-VRF-Selection ip vrf receive VRF1 ip vrf receive VRF2 ip vrf receive VRF3
Configuring Multi-VRF Selection in a Route Map Example
The following example shows a set ip vrf next-hop command that applies policy-based routing to the VRF interface named myvrf and specifies that the IP address of the next hop is 10.0.0.2:
Router(config)# route-map map1 permit Router(config)# set vrf myvrf Router(config-route-map)# set ip vrf myvrf next-hop 10.0.0.2 Router(config-route-map)# match ip address 101 Router(config-route-map)# end
The following example shows a set ip global command that specifies that the router should use the next hop address 10.0.0.1 in the global routing table:
Router(config-route-map)# set ip global next-hop 10.0.0.1
Additional References
Related Documents
Related Topic |
Document Title |
---|---|
MPLS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples |
Cisco IOS Multiprotocol Label Switching Command Reference |
IP access list commands |
Cisco IOS Security Command Reference |
Standards
Standard |
Title |
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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. |
-- |
MIBs
MIB |
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 software releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFCs
RFC |
Title |
---|---|
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
-- |
Technical Assistance
Description |
Link |
---|---|
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. |
Feature Information for Multi-VRF Selection Using Policy-Based Routing
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1 | Feature Information for Multi-VRF Selection Using Policy-Based Routing |
Feature Name |
Releases |
Feature Information |
---|---|---|
Multi-VRF Selection Using Policy-Based Routing (PBR) |
Cisco IOS XE Release 2.2 |
The Multi-VRF Selection Using Policy-Based Routing (PBR) feature allows a specified interface on a provider edge (PE) router to route packets to VPNs based on packet length or match criteria defined in an IP access list. This feature and the VRF Selection Based on Source IP Address feature can be configured together on the same interface. In Cisco IOS XE Release 2.2, this feature was introduced on the Cisco ASR 1000 Series Aggregation Services Routers. The following commands were modified: set ip global, set ip vrf next-hop, and set vrf. |
Glossary
CE router--customer edge router. A router that is part of a customer network and that interfaces to a provider edge (PE) router.
Inherit-VRF routing--Packets arriving at a VRF interface are routed by the same outgoing VRF interface.
Inter-VRF routing--Packets arriving at a VRF interface are routed via any other outgoing VRF interface.
IP --Internet Protocol. Network layer protocol in the TCP/IP stack offering a connectionless internetwork service. IP provides features for addressing, type-of-service specification, fragmentation and reassembly, and security. Defined in RFC 791.
PBR --policy-based routing. PBR allows a user to manually configure how received packets should be routed.
PE router--provider edge router. A router that is part of a service provider's network and that is connected to a CE router. It exchanges routing information with CE devices by using static routing or a routing protocol such as BGP, RIPv1, or RIPv2.
VPN --Virtual Private Network. A collection of sites sharing a common routing table. A VPN provides a secure way for customers to share bandwidth over an ISP backbone network.
VRF --A VPN routing and forwarding instance. A VRF consists of an IP routing table, a derived forwarding table, a set of interfaces that use the forwarding table, and a set of rules and routing protocols that determine what goes into the forwarding table.
VRF-lite --A feature that enables a service provider to support two or more VPNs, where IP addresses can be overlapped among the VPNs.
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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.