This article explain the reason for the event "mroute: pending queue full. dropping entries" in /var/log/messages fileThe following kernel event may appear in /var/log/messages file when using PIM to route multicast traffic:
Sep 15 19:23:36 fw_1 kernel: mroute: pending queue full, dropping entries.
Some of the mroute entries show "Register" as the outgoing interface in NSM. For example:
NSM# show ip mroute
IP Multicast Routing Table
Flags: I - Immediate Stat, T - Timed Stat, F - Forwarder installed
Timers: Uptime/Stat Expiry
Interface State: Interface (TTL)
(192.168.1.1, 184.108.40.206), uptime 00:05:45, stat expires 00:02:03
Owner PIM-SM, Flags: TF
Incoming interface: inside
Outgoing interface list:
When a streamer start sending its' video channel, the first hop router registers a new multicast group with the Rendezvous Point (RP).
Until the router receives a confirmation from the RP (PIM register-stop signal), the mroute entry is in the Register state and clients can not join the multicast group.
There can be various reasons for a channel not to get registered with the RP.