IP SLA has been made VRF aware. This means that it can run inside a VRF on PE routers. Therefore, you can use IP SLA to measure the network performance inside the VPN from the PE routers. IP SLA can, for instance, measure the RTT between PE routers inside the customer VRF. From the PE router, the IP SLA probes are forwarded using the VRF routing table. Equally, the IP SLA can run on multi-VRF CE routers. To make IP SLA run over MPLS VPN, you must put the rtr probe into the correct VRF. Look at Figure 14-9 to see a network in which the IP SLA source has been put on the PE router. You can put the IP SLA in multiple VRF instances and measure the network performance toward the remote CE routers or the PE routers if you put the IP SLA responder in the appropriate VRF.

Figure 14-9 IP SLA for MPLS VPN

Figure 14-9 IP SLA for MPLS VPN

In Example 14-18, the rtr 1 probe has been put in VRF cust-one. Example 14-18 IP SLA for a VRF

rtr 1

type jitter dest-ipaddr dest-port 5000 source-ipaddr vrf cust-one request-data-size 100 rtr schedule 1 start-time now

For accuracy of the measurements, it is advisable that you use dedicated routers for IP SLA. These routers are often referred to as shadow routers. Because these routers are dedicated to IP SLA, they are not involved in packet forwarding and can spend all of their CPU processing on IP SLA. If the shadow routers are attached to PE routers as CE routers and you have one shadow router per point of presence (POP), you can measure the performance of the MPLS VPN backbone from every POP to every other POP. If these routers are attached to PE routers as multi-VRF CE routers, they can actually perform CE-to-CE measurements across the MPLS VPN network for several VPNs. It then suffices to have one shadow router per POP in the network. Look at Figure 14-10 for an MPLS VPN network with shadow IP SLA CE routers measuring the performance POP to POP.

Figure 14-10 Shadow IP SLA CE Routers



/PE / i







Service Provider MPLS VPN Network

Service Provider MPLS VPN Network

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