[c-nsp] C6k 6708 Input drops
Peter Rathlev
peter at rathlev.dk
Thu Apr 16 15:35:52 EDT 2009
I really hate to ask this question, since input drops/discards and micro
bursts have been discussed so much. I just can't grasp this.
The question is: what are "input drops" that don't show up in "counters
errors" or "queueing", but do show up in "show platform hardware
capacity interfaces"?
Recently we started seeing "input drops" on a 6708 card in Cat6500
running SXF. The other end is the exact samer and the connection in both
ends is 10G LR running 5m to a DWDM circuit carrying it ~50 km. It's a
L3 (no switchport) MPLS link.
The errors appear every twenty minutes very precisely and every time
about 100 packets are dropped "all at once" as far as I can tell. I
don't understand how one end could send micro bursts faster than the
other end could send them when interfaces are similar. (We're also
working on tracking the source/finding out what it is of course.)
The link is hardly used; we're talking peaks of about 40-50 kpps and
400-600 Mbit/s when looking a 5 min Cacti graphs.
The other end doesn't report any errors. It started appearing at a time
where we had just _removed_ some traffic from this link logically. I
don't assume it's related to link layer problems so we haven't tried
replacing anything yet for the same reason.
A "show interface counters errors" shows (almost) nothing:
xxx-1#sh int te6/5
...
Input queue: 1/75/121167/12 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 215774000 bits/sec, 31160 packets/sec
30 second output rate 317290000 bits/sec, 33704 packets/sec
L2 Switched: ucast: 69130383 pkt, 6313188185 bytes - mcast: 11526118 pkt, 1281021706 bytes
L3 in Switched: ucast: 617967640725 pkt, 514240136083975 bytes - mcast: 0 pkt, 0 bytes mcast
L3 out Switched: ucast: 589404552537 pkt, 526530456915283 bytes mcast: 0 pkt, 0 bytes
618049766059 packets input, 514245988339000 bytes, 0 no buffer
Received 15285284 broadcasts (0 IP multicasts)
0 runts, 349752298 giants, 1785 throttles
14 input errors, 14 CRC, 2 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
590212510115 packets output, 531857495170458 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
xxx-1#
xxx-1#sh int te6/5 counters errors
Load for five secs: 6%/3%; one minute: 4%; five minutes: 4%
Time source is NTP, 21:19:04.267 CEST Thu Apr 16 2009
Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize OutDiscards
Te6/5 0 14 0 14 0 0
Port Single-Col Multi-Col Late-Col Excess-Col Carri-Sen Runts Giants
Te6/5 0 0 0 0 0 0 350685137
Port SQETest-Err Deferred-Tx IntMacTx-Err IntMacRx-Err Symbol-Err
Te6/5 0 0 0 0 2
xxx-1#
xxx-1#sh queueing int te6/5
...
Packets dropped on Receive:
BPDU packets: 0
queue dropped [cos-map]
---------------------------------------------
1 0 [0 1 2 3 4 5 6 7 ]
2 0 []
3 0 []
4 0 []
5 0 []
6 0 []
7 0 []
8 0 []
xxx-1#sh pl hard cap fabric
Load for five secs: 1%/0%; one minute: 5%; five minutes: 5%
Time source is NTP, 21:28:56.577 CEST Thu Apr 16 2009
Switch Fabric Resources
Bus utilization: current: 0%, peak was 0% at 21:28:47 CEST Thu Apr 16 2009
Fabric utilization: Ingress Egress
Module Chanl Speed rate peak rate peak
1 0 20G 0% 4% @00:08 11Oct08 0% 4% @20:47 24Aug08
1 1 20G 0% 10% @09:36 28Feb09 0% 8% @13:25 28Jul08
2 0 20G 0% 0% 0% 1% @06:38 18Jul08
2 1 20G 1% 9% @13:25 28Jul08 0% 10% @02:05 13Feb09
4 0 20G 0% 2% @11:43 15Sep08 0% 4% @19:35 22Feb09
5 0 20G 0% 5% @09:16 03Sep08 0% 5% @09:16 03Sep08
6 0 20G 0% 11% @10:46 08Apr09 0% 14% @03:09 21Feb09
6 1 20G 0% 15% @12:31 26Jan09 1% 14% @12:32 26Jan09
Switching mode: Module Switching mode
1 compact
2 compact
4 compact
5 compact
6 compact
xxx-1#sh pl hard cap interface
Load for five secs: 8%/4%; one minute: 6%; five minutes: 5%
Time source is NTP, 21:30:12.802 CEST Thu Apr 16 2009
Interface Resources
Interface drops:
Module Total drops: Tx Rx Highest drop port: Tx Rx
1 1843 16 13 41
2 105657 0 13 0
4 0 1 0 1
6 0 121269 0 5
Interface buffer sizes:
Module Bytes: Tx buffer Rx buffer
1 1221120 173504
2 1221120 173504
4 1221120 173504
6 91889216 109296640
xxx-1#
Maybe I should just become a gardener instead... :-)
Thanks,
Peter
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