Design Reference

In Figure 33: SPBM implementation options on page 79, node VSP-G acts as a BCB for the
service, and has no IP configuration.
B—Layer 2 VSN
A Layer 2 Virtual Services Network (VSN) bridges customer VLANs (C-VLANs) over the SPBM
core infrastructure. A Layer 2 VSN associates a C-VLAN with an I-SID, which is then virtualized
across the backbone. All VLANs in the network that share the same I-SID can participate in
the same VSN. If you want IS-IS to distribute traffic across two equal cost paths, then you need
two backbone VLANs (B-VLAN) with a primary B-VLAN and a secondary B-VLAN. Otherwise,
you need only a single B-VLAN.
One of the key advantages of the SPBM Layer 2 VSN is that network virtualization provisioning
is achieved by configuring the edge of the network (BEBs) only. The intrusive core provisioning
that other Layer 2 virtualization technologies require is not needed when new connectivity
services are added to the SPBM network. For example, when new virtual server instances are
created and need their own VLAN instances, they are provisioned at the network edge only
and do not need to be configured throughout the rest of the network infrastructure.
Based on its I-SID scalability, this solution can scale much higher than any 802.1Q tagging
based solution. Also, due to the fact that there is no need for Spanning Tree in the core, this
solution does not need any core link provisioning for normal operation. Redundant connectivity
between the C-VLAN domain and the SPBM infrastructure can be achieved by operating two
SPBM switches in switch clustering (SMLT) mode. This allows the dual homing of any
traditional link aggregation capable device into an SPBM network
Note:
In the current release, VSP 4000 does not support Inter-Switch Trunking (IST), and hence
cannot be provisioned as S-MLT peer nodes.
In
Figure 33: SPBM implementation options on page 79, nodes VSP-C and VSP-D act as BEBs
for the VSN. Only these nodes have a MAC table or forwarding database for C-VLAN 10.
C—Layer 2 VSN with VLAN translation
Layer 2 VSNs with VLAN translation are basically the same as the Layer 2 VSNs, except that
the BEBs on either end of the SPBM network belong to different VLANs. This option enables
you to connect one VLAN to another VLAN. In
Figure 33: SPBM implementation options on
page 79, VLAN 9 connects to VLAN 19. The mechanism that connects them is that they use
the same I-SID (12990009).
D— Inter-VSN routing
Inter-VSN routing allows routing between Layer 2 VLANs with different I-SIDs. You can use
Inter-VSN routing to redistribute routes between Layer 2 VLANs. This option allows effective
networking of multiple VSNs. Where Layer 2 VSN with VLAN translation enabled you to
interconnect VLANs, this option takes that concept one step further and allows you to
interconnect VSNs. This option also provides the ability to route IP traffic on Layer 2-VSNs that
enter on NNI interfaces, which is especially useful for Layer 2 edge solutions.
As seen in
Figure 33: SPBM implementation options on page 79, routing between VLANs 11
and 12 occurs on the SPBM core switch VSP-G shown in the middle of the figure. With Inter-
VSN routing enabled, VSP-G transmits traffic between VLAN 11 (I-SID 12990011) and VLAN
SPBM design guidelines
80 Network Design Reference for Avaya VSP 4000 February 2014
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