Avaya 8800 Planning And Engineering, Network Design page 170

SPBM design guidelines
new primary. In this scenario, the IS-IS adjacency goes down because the default hold
time (27 seconds) is too short. To prevent this from happening, increase the Hello
multiplier to allow more time for the HA failover.
SPBM NNI SMLT
For NNI-facing MLT splitting towards two IST peers, only one link is supported in each direction
towards each of the IST switches.
Multicast
• Ethernet Routing Switch 8800/8600 does not support NLB-multicast and NLB-multicast with
IGMP for SPBM.
• SPBM supports enabling IGMP snooping on a C-VLAN, but it does not support enabling PIM
on a C-VLAN.
If IGMP snooping is enabled on a C-VLAN, then its operating mode would be Layer 2 Virtual
Services Network with IGMP support on the access networks for optimized forwarding of IP
Multicast traffic in a bridged network (L2 VSN with Multicast).
• The BEB should be the only IGMP querier in the network.
Important:
If the BEB receives an IGMP query from any other device, it causes the BEB to disable the
Multicast over SPBM on that VLAN, send a trap, and wait for the situation to be resolved,
which may require operator intervention.
• Multicast over SPBM does not integrate PIM functionality so the following considerations apply
when connecting to a PIM network:
- You must configure Static IGMP receivers on the BEB access interface facing the PIM
network when the sender is on the SPB access network and the receiver is on the PIM
network. Static IGMP receivers make the PIM router accept streams and avoids a Reverse
Path Forwarding (RPF) check that may change the source of the stream.
- You must configure Static IGMP receivers on the PIM interface facing the SPB Multicast
network when the sender is on the PIM network and the receiver is on the SPB access
network.
- You must configure ACLs on the BEB facing the PIM network for security.
• SSM Snoop must be enabled before setting IGMP version to 3 and both ssm-snoop and
snooping must be enable for IGMPv3.
VLACP
VLACP is generally used when a repeater or switch exists between connected Ethernet Routing
Switch 8800/8600 switches to detect when a connection is down even when the link light is up. If
you have VLACP configured on an SPBM link that is also an IST link, during a connection fail over
(where the link lights stay up) the IS-IS hellos time out first (after 27 seconds, using default values)
and take down the IS-IS adjacency. IS-IS then calculates the new shortest path and fails over the
SPBM traffic. Then, 90 seconds after the connection failure (using default values), VLACP goes
down but the IST link was already taken down by IS-IS.
In this scenario, there is no data traffic impact since IS-IS can find another path in the SPBM
network before VLACP goes down.
June 2016 Planning and Engineering — Network Design
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