Design Reference

advertising their reachable IP routes into IS-IS and installing IP routes learned from IS-IS. Suitable
IP redistribution policies need to be defined to determine what IP routes a BEB will advertise to IS-
IS.
As seen in Figure 45: SPBM implementation options on page 98, the green VRF on VSP-C is
configured to advertise its local or direct IP routes into IS-IS within I-SID 13990001. The VRF on
node VSP-D, which is also a member of the same I-SID, installs these IP routes in its VRF IP
routing table with a next-hop B-MAC address of VSP-C. Therefore, when the VRF on node VSP-D
needs to IP route traffic to the IP subnet off VSP-C, it performs a lookup in its IP routing table and
applies a MAC-in- MAC encapsulation with B-MAC DA of VSP-C. The SPBM core ensures delivery
to the egress BEB VSP-C where the encapsulation is removed and the packet is IP routed onward.
Note:
Like the IP shortcut service, there are only two IP routing hops (ingress BEB and egress BEB)
as the SPBM backbone acts as a virtualized switching backplane.
F—Layer 3 VSN
Figure 45: SPBM implementation options on page 98 shows two VRFs (green and red) to illustrate
that the BEBs can associate I-SIDs with multiple VRFs. The Layer 3 VSN option provides IP
connectivity over SPBM for all of your VRFs.
G—Layer 2 VSN and Layer 3 VSN
Figure 45: SPBM implementation options on page 98 shows both a Layer 2 VSN and a Layer 3 VSN
to show that you can configure both options on the same BEBs. This topology is simply made up of
a number of BEBs that terminate VSNs of both types. This example illustrates the flexibility to
extend one or more edge VLANs (using one or more Layer 2 VSNs) to use a default gateway that is
deeper in the SPBM core. From here, traffic can then be IP routed onward as either nonvirtualized
with IP shortcuts or, as shown in this example, with a virtualized Layer 3 VSN. Note that in this
example the central node VSP-G is now also acting as BEB for both service types as it now
maintains both a MAC table for the Layer 2 VSN it terminates, and an ARP cache and IP routing
table for the Layer 3 VSN it also terminates.
Multiple tenants using different SPBM services
The following figure shows multiple tenants using different services within an SPBM metro network.
In this network, you can use some or all of the SPBM implementation options to meet the needs of
the community while maintaining the security of information within VLAN members.
SPBM design guidelines
100 Network Design Reference for Avaya VSP 4000 Series June 2015
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