IPv6 PIM Register Message Rate Limit
When a new source begins transmitting
within a IPv6 Protocol Independent Multicast (PIMv6) network, the designated router
(DR)
encapsulates multicast packets into register messages and forwards them to the rendezvous
point (RP). If the source is running at a high data rate with many new sources starting
concurrently, pressure can be put on the CPU due to the large number of multicast
packet
streams being sent to the network. This situation can occur after a network or power
failure. To avoid this scenario, the rate limit for the number of register messages
should
be set to a relatively low value. The rate limit for the number of register messages
can be
set to a relatively low value to avoid adverse pressure on the CPU when numerous sources
start concurrently. This value is based on the known number of multicast sources
present.
The following values apply when configuring register message rate limiting usable in both DR and RP switches:
- For a DR, the default rate limit is set to one message per second.
- For an RP, the default rate limit is set to one message per second. The maximum supported rate can be set to 50 packets per second (pps) for all (S, G) pairs counted per VRF.
Note: In an RP, where both the PIM register
message filter rule and the PIM register message rate limit are configured, filtering
functionality takes precedence over rate limiting.
Note: The register rate limit works only when
a S,G, or *G entry is created in the Multicast Forwarding Information Base (MFIB).
In
the absence of them, the rate limit fallbacks to a global 1000pps rate. The rate limit
cannot be enforced until the entry is created in the MFIB. Entry creation usually
takes
some finite amount of time on reception of register message, after which the rate
limit
is enforced.
When PIM register message rate limit is not configured, a RUCKUS ICX network stack allows a maximum of 1000 register messages for software forwarding. When PIM register message rate limit is configured, the maximum number of supported register messages is 50 per device or VRF.