Multicast traffic not showing up in interface counters
Page 1 of 1

Author:  ryderse [ Fri Jul 26, 2013 5:07 pm ]
Post subject:  Multicast traffic not showing up in interface counters


I've built a lab in GNS3 with a server that streams multicast traffic, single source MC in fact.

In GNS3 this server is connected to the default GNS3 Ethernet Switch and then to a Cisco 3745 router on Fa0/0.

I did a packet capture on Fa0/0 and I see plenty of traffic coming in. In 18 secs I captured 28k packets. However, looking at the interface counters on Fa0/0 there appears to be almost nothing coming in.

Does anyone know if this is normal or perhaps a bug or must I enable PIM first? I have not seen this type of behavior before.

Thank you,

Cisco IOS Software, 3700 Software (C3745-IPBASEK9-M), Version 12.4(23), RELEASE SOFTWARE (fc1)

R1-3745#show interfaces fastEthernet 0/0
FastEthernet0/0 is up, line protocol is up
Hardware is Gt96k FE, address is c401.08dc.0000 (bia c401.08dc.0000)
Internet address is
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Last input 00:06:11, output 00:00:07, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
93 packets input, 6122 bytes
Received 34 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog
0 input packets with dribble condition detected
309 packets output, 30205 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

Author:  ryderse [ Fri Aug 16, 2013 3:49 pm ]
Post subject:  Re: Multicast traffic not showing up in interface counters

Thanks goldb328.

No, there is no FW in this picture however, I have resolved this issue.

Once multicast routing was enabled, the counters began to register this traffic. Interesting that it behaves this way, the traffic was definitely there hitting the interface.

Anyway, this is resolved.

Thanks again,

Page 1 of 1 All times are UTC
Powered by phpBB® Forum Software © phpBB Group