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Knowledge Base

Multicast packets dropped on S9300

Publication Date:  2014-09-12  |   Views:  1065  |   Downloads:  0  |   Author:  SU1102283537  |   Document ID:  EKB1000040245


Issue Description

The problem is IPTV service image freeze. This is the main symtom. The image freeze is due to multicast packet lost. We isolate the problem in the traffic between two different devices, one S8508 and one S9312.
It happens when we try to migrate S8512 devices to S9312 equipment. This problem only affects one remote equipment, S5808. In the original situation the S8512 worked OK, and the IPTV service was not affected.
Other routers we have migrated,were working fine, there were no problem with any service.

Alarm Information


Handling Process

We reviewed the fibers connecting to the S9312 and the transmission device, and we found a problem with this fiber.
Even the fiber had problems, the only end to end service affected was the IPTV, other services worked ok, and this is because any multicast

Root Cause

The main service affected was the IPTV because this traffic (multicast) is very sensitive to packets dropped.
The clue to solve this problem was that we have two interfaces configured in an Eth-Trunk, and checking the multicast packets discarded with an IPTV probe, we saw that only odd multicast channels (x.x.x.1, x.x.x.3, x.x.x.5 ...) failed, and the even channels (x.x.x.2, x.x.x.4, x.x.x.6 ...) worked OK.
The hashing function in the S9312 that load balance multicast traffic, is based on the multicast IP address, so in the Eth-Trunk, the odd multicast IPs go in one interface, and the even IPs in the other.