Design Reference

Table Of Contents
- If you do manually change the system ID, take the necessary steps to ensure no
duplication exists in the network.
Create two B-VLANs to allow load distribution over both B-VLANs. This configuration is
required if you use SMLT. Even if you do not use SMLT in the network, this is still good
practice as adding a second B-VLAN to an existing configuration allows SPBM to load
balance traffic across two equal cost multipaths if the physical topology grants it.
In a ring topology with OSPF and IS-IS configured in the core, a core link break causes
slow convergence that can lead to SPBM Layer 2 traffic loss. If the last member link of
an OSPF VLAN fails, it takes down the IP interface and OSPF reconverges. While OSPF
reconverges, SPBM does not have access to the CPU, which causes traffic loss.
SPBM
The following list identifies best practices for SPBM:
Use a different, easily recognizable IS-IS nickname on each switch.
If you enable IP shortcuts, you must configure an IS-IS IP source address on the
switch.
Physical or MLT links between IS-IS switches
Virtual Services Platform supports only a single port or single MLT between a pair of IS-IS
switches. For example, if two individual ports exist between a pair of IS-IS switches, you can
configure IS-IS on both the ports but an IS-IS adjacency only forms on one of the links.
If you configure a single MLT between a pair of IS-IS switches, all ports in the MLT are used.
You must configure the MLT before you enable IS-IS on the MLT.
CFM using manual mode configuration
Important:
Avaya recommends auto-configuration of CFM, which is simpler than the manual mode of
configuration.
For more information on these commands, see Avaya Command Line Reference,
NN46251–104.
The following list identifies best practices for manual configuration of Connectivity Fault
Management (CFM):
The CFM domain name must be the same on all switches in an IS-IS area.
The maintenance association must be the same on all switches in an IS-IS area.
To use CFM testing over both B-VLANs, create two maintenance associations one for
each B-VLAN.
You can configure the same maintenance domain intermediate points (MIP) on all
switches in an IS-IS area or uniquely defined per switch.
SPBM design guidelines
102 Network Design Reference for Avaya VSP 4000 February 2014
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