Please help - Input queue dropping packets

jinmo1978 · ‎04-15-2008

Hello People,

We have a router, getting a 100 mg feed, which are mulitcast traffic. When I check the interface, input queue size is 0, and it never builds up, but time to time it just drops packets and "drops" counter goes up.

Input queue: 0/4096/511609/39 (size/max/drops/flushes); Total output drops: 0

511609 input errors, 0 CRC, 0 frame, 0 overrun, 511609 ignored

When I check the buffer, there is 0 misses in cache.

FastEthernet3/0 buffers, 768 bytes (total 529, permanent 400):

129 in free list (128 min, 1200 max allowed)

357 hits, 43 misses, 12 trims, 141 created

0 failures (0 no memory)

400 max cache size, 271 in cache

132768571 hits in cache, 0 misses in cache

14 buffer threshold, 0 threshold transitions

Can somebody explain to me why this is happening?

Thank you so much for your time

-Jinmo

Edison Ortiz · ‎04-16-2008

That's normal on a multicast interface as the traffic is bursty by design.

To address some of your concerns:

1) the input queue size is 0 (minimum value)

2) the input queue size is 4096 (maximum value)

Those are the first 2 values in that line (that's your window). You can modify the maximum value with the hold-queue [value] in under the interface. However, I don't see the need for that as you currently have the max.

The other 2 values are self-explanatory.

That's the nature of multicast, it's up to the application to resend the multicast stream that was dropped, if needed.

HTH,

__

Edison.