Cisco Catalyst 3750 - Multi-VRF CE Configuration Guidelines

28-79
Catalyst 3750 MetroSwitch Software Configuration Guide
78-15870-01
Chapter 28 Configuring IP Unicast Routing
Configuring Multi-VRF CE
Multi-VRF CE Configuration Guidelines
These are considerations when configuring VRF in your network:
• A switch with multi-VRF CE is shared by multiple customers, and each customer has its own routing
table.
• Because customers use different VRF tables, the same IP addresses can be reused. Overlapped IP
addresses are allowed in different VPNs.
• Multi-VRF CE lets multiple customers share the same physical link between the PE and the CE.
Trunk ports with multiple VLANs separate packets among customers. Each customer has its own
VLAN.
• Multi-VRF CE does not support all MPLS-VRF functionality. It does not support label exchange,
LDP adjacency, or labeled packets.
• For the PE router, there is no difference between using multi-VRF CE or using multiple CEs. In
Figure 28-6, multiple virtual Layer 3 interfaces are connected to the multi-VRF CE device.
• The switch supports configuring VRF by using physical ports, VLAN SVIs, or a combination of
both. The SVIs can be connected through an access port or a trunk port.
• The switch supports a total of 26 VRFs and VPNs.
• A customer can use multiple VLANs as long as they do not overlap with those of other customers.
A customer’s VLANs are mapped to a specific routing table ID that is used to identify the
appropriate routing tables stored on the switch.
• A switch using VRF can support one global network and up to seven VRFs.
• Most routing protocols (BGP, OSPF, IS-IS , RIP, and static routing) can be used between the CE and
the PE. However, we recommend using external BGP (EBGP) for these reasons:
– BGP does not require multiple algorithms to communicate with multiple CEs.
– BGP is designed for passing routing information between systems run by different
administrations.
– BGP makes it easy to pass attributes of the routes to the CE.
• Multi-VRF-CE does not support IGRP and EIGRP.
• Multi-VRF CE does not affect the packet switching rate.
• VPN multicast is not supported.
• When multi-VRF CE is configured, you cannot assign the same Hot Standby Routing Protocol
(HSRP) standby address to two different VPNs.
• VRFs are not compatible with the PBR template. If you configure the PBR template by entering the
sdm prefer routing-pbr command, any preconfigured VRFs are removed from the configuration.
PBR and VRFs cannot function on the same switch.