[c-nsp] 6500 (Sup7203-bxl / 6724-SFP) Input queue drops

[Drew Weaver]

Hi there, I've been slowly working through some issues with our new 6500 deployment and I've noticed something a little strange.

I'm noticing input queue drops on a few of the port-channels that go between the Core -> Border, the queue drops do not show up on the physical ports, only on the Port-Channel interface itself and they do not show up on our Border Internet Routers (GSRs) only on these two core routers (6500s).

I'm noticing that almost constantly there is Protocol 17 (UDP), TTL 1 traffic in the buffer:

Sw#sh buffers input po6 header

Buffer information for Small buffer at 0x44ED8868
  data_area 0x804E4C4, refcount 1, next 0x0, flags 0x200
  linktype 7 (IP), enctype 1 (ARPA), encsize 14, rxtype 1
  if_input 0x50F110A8 (Port-channel6), if_output 0x0 (None)
  inputtime 1d02h (elapsed 00:07:31.632)
  outputtime 1d02h (elapsed 00:03:48.208), oqnumber 65535
  datagramstart 0x804E53A, datagramsize 90, maximum size 308
  mac_start 0x804E53A, addr_start 0x804E53A, info_start 0x0
  network_start 0x804E548, transport_start 0x804E55C, caller_pc 0x41714A8C

  source: x.x.100.34, destination: x.x.129.209, id: 0x39B6, ttl: 1,
  TOS: 0 prot: 17, source port 1805, destination port 1808

Buffer information for Small buffer at 0x44EE8110
  data_area 0x805BFC4, refcount 1, next 0x0, flags 0x200
  linktype 7 (IP), enctype 1 (ARPA), encsize 14, rxtype 1
  if_input 0x50F110A8 (Port-channel6), if_output 0x0 (None)
  inputtime 1d02h (elapsed 00:01:29.912)
  outputtime 1d02h (elapsed 00:02:25.964), oqnumber 65535
  datagramstart 0x805C03A, datagramsize 102, maximum size 308
  mac_start 0x805C03A, addr_start 0x805C03A, info_start 0x0
  network_start 0x805C048, transport_start 0x805C05C, caller_pc 0x41714A8C

  source: x.x.16.178, destination: x.x.129.222, id: 0x789C, ttl: 1,
  TOS: 0 prot: 17, source port 8728, destination port 16438

The sources so far have always been a local host downstream from the core and the destination is always a host on the Internet.

Although if this is in the Input buffer, the source and destination could be reversed.

-Drew