OSPF Support for Unlimited Software VRFs per PE Router
Last Updated: October 27, 2011
In a Multiprotocol Label Switching--Virtual Private Network (MPLS-VPN) deployment, each VPN routing and forwarding instance (VRF) needs a separate Open Shortest Path First (OSPF) process when configured to run OSPF. The OSPF Support for Unlimited Software VRFs per Provider Edge (PE) Router feature addresses the scalability issue for OSPF VPNs by eliminating the OSPF VPN limit of 32 processes.
History for the OSPF Support for Unlimited Software VRFs per Provider Edge Router Feature
This feature was introduced.
This feature was integrated into Cisco IOS Release 12.0(27)S.
This feature was integrated into Cisco IOS Release 12.2(25)S.
This feature was integrated into Cisco IOS Release 12.2(18)SXE.
This feature was integrated into Cisco IOS Release 12.2(27)SBC.
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Prerequisites for OSPF Support for Unlimited Software VRFs per PE Router
You must have OSPF configured in your network.
Restrictions for OSPF Support for Unlimited Software VRFs per PE Router
Only 32 processes per VRF can be supported. For different VRF processes, there is no limit.
Information About OSPF Support for Unlimited Software VRFs per PE Router
Before Cisco IOS Releases 12.3(4)T and 12.0(27)S, a separate OSPF process was necessary for each VRF that receives VPN routes via OSPF. When VPNs are deployed, an MPLS Provider Edge (PE) router will be running both multiprotocol Border Gateway Protocol (BGP) for VPN distribution, and Interior Gateway Protocol (IGP) for PE-P connectivity. It is a common scenario when OSPF is used as the IGP between a customer edge (CE) router and a PE router. OSPF was not scalable in VPN deployment because of the limit of 32 processes. By default one process is used for connected routes and another process is used for static routes, therefore only 28 processes can be created for VRFs.
The OSPF Support for Unlimited Software VRFs per Provider Edge Router feature allows for an approximate range of 300 to 10,000 VRFs, depending on the particular platform and on the applications, processes, and protocols that are currently running on the platform.
How to Configure OSPF Support for Unlimited Software VRFs per PE Router
Example Verifying OSPF Support for Unlimited Software VRFs per PE Router
This example illustrates the output display from theshowipospf command to verify that the OSPF VRF process 12 has been created for the VRF named first. The output that relates to the VRF first appears in bold.
Router# show ip ospf 12main ID type 0x0005, value 0.0.0.100 Supports only single TOS(TOS0) routes Supports opaque LSA Supports Link-local Signaling (LLS) Supports area transit capability Connected to MPLS VPN Superbackbone, VRF first It is an area border router Initial SPF schedule delay 5000 msecs Minimum hold time between two consecutive SPFs 10000 msecs Maximum wait time between two consecutive SPFs 10000 msecs Incremental-SPF disabled Minimum LSA interval 5 secs Minimum LSA arrival 1000 msecs LSA group pacing timer 240 secs Interface flood pacing timer 33 msecs Retransmission pacing timer 66 msecs Number of external LSA 0. Checksum Sum 0x0 Number of opaque AS LSA 0. Checksum Sum 0x0 Number of DCbitless external and opaque AS LSA 0 Number of DoNotAge external and opaque AS LSA 0 Number of areas in this router is 1. 1 normal 0 stub 0 nssa Number of areas transit capable is 0 External flood list length 0 Area BACKBONE(0) Number of interfaces in this area is 1 Area has no authentication SPF algorithm last executed 00:00:15.204 ago SPF algorithm executed 2 times Area ranges are Number of LSA 1. Checksum Sum 0xD9F3 Number of opaque link LSA 0. Checksum Sum 0x0 Number of DCbitless LSA 0 Number of indication LSA 0 Number of DoNotAge LSA 0 Flood list length 0
The following sections provide references related to the OSPF Support for Unlimited Software VRFs per Provider Edge Router feature.
Cisco IOS IP Routing: OSPF Configuration Guide
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multiprotocolBGP--Border Gateway Protocol (BGP) can be used as an interdomain routing protocol in networks that use Connectionless Network Service (CLNS) as the network-layer protocol.
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