When a Layer 2 Virtual Service Network (VSN) extends outside of the Distributed Virtual Routing (DvR) domain, DvR Controllers can route traffic that enters on the network-to-network interface (NNI) by using Virtual Router Redundancy Protocol (VRRP) to advertise the DvR gateway MAC in Layer 2 VSN.
The primary Virtual Router Redundancy Protocol (VRRP) router, in this case, a DvR Controller, sends VRRP advertisements on the DvR-election VLAN using the VRRP gateway MAC as the source and a unique nickname-derived IP address as the source IP. The primary VRRP router sends VRRP advertisements on all other DvR VLANs using the VRRP gateway MAC as the source and the configured interface IP address as the source IP. The primary or backup VRRP routers process VRRP advertisements only on the selected VRRP election VLAN/I-SID. (The primary VRRP router is sometimes referred to as the master.)
Note
The VRRP gateway MAC is the same as the DvR gateway MAC.
Non-DvR Backbone Edge Bridges (BEBs) learn the gateway MAC from the advertisements and encapsulate packets destined to the DvR gateway MAC with the primary VRRP router backbone MAC (BMAC) destination address. The primary VRRP router routes the packets to the destination.
The destination IP address can be any of the following:
The DvR host route on any DvR Controller or Leaf node in any domain.
An ARP entry in another DvR VLAN and I-SID for a host that attaches to a non-DvR BEB.
A subnet route from IS-IS like IP Shortcuts or Layer 3 VSN.
An ARP entry or subnet route from any protocol in a non-DvR routable VLAN or I-SID.
DvR-VRRP Coexistence has the following restrictions:
You can only configure this functionality on a DvR Controller.
Controllers that participate in DvR VRRP must meet the following conditions:
Controllers must use the same DvR I-SIDs and the same election I-SID. For example, if Controller 1 and Controller 2 both have DvR VLAN 200 with I-SID 20200 and DvR VLAN 202 with I-SID 20202, they must both use the same I-SID to determine their VRPP role (Primary / Backup).
Controllers must be in the same IS-IS area.
The next-hop IP address for hosts that attach to non-DvR BEBs on a DvR I-SID must be the same as the DvR gateway IP address for that I-SID.
VRRP Primary and Backup routers must have all interconnected I-SIDs (I-SIDs extended to non-DvR BEBs) configured as DvR interfaces in their domain.
In any DvR ISID the only supported VRRP routers are DvR Controllers with DvR VRRP enabled. Interoperation with non-DvR VRRP routers is not supported.