Packet drops & overruns on WS-X6704-10GE card

[odnoralets]

Hi, All

I am getting packet drops between 2 10GE directrly connected WS-C6509 WS-SUP720-3BXL with WS-X6704-10GE card

And the problem is the overrun counter increased sometimes.

Please check the following show interfaces output:

cat01#sh interface TenGigabitEthernet 2/1

TenGigabitEthernet2/1 is up, line protocol is up (connected)

Hardware is C6k 10000Mb 802.3, address is 0019.30cf.044c (bia 0019.30cf.044c)

Description:

MTU 9216 bytes, BW 10000000 Kbit, DLY 10 usec,

reliability 255/255, txload 105/255, rxload 74/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 10Gb/s

input flow-control is off, output flow-control is off

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:44, output 00:00:55, output hang never

Last clearing of "show interface" counters 02:25:34

Input queue: 0/2000/78174753/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

30 second input rate 2912906000 bits/sec, 666308 packets/sec

30 second output rate 4119605000 bits/sec, 697987 packets/sec

5819516348 packets input, 3156853100134 bytes, 0 no buffer

Received 145047 broadcasts (145035 multicasts)

0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 39126414 overrun, 0 ignored

0 watchdog, 0 multicast, 0 pause input

0 input packets with dribble condition detected

6007427035 packets output, 4505148332026 bytes, 0 underruns

0 output errors, 0 collisions, 0 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

cat01#

Please let me know what could be the reson for this and how to start trouble shooting for this issue.

Thanks

[Giuseppe Larosa]

Hello,

if losses are not real may be the following case applies:

CSCsj70658

Symptoms: Counters on 4th interface of a WS-X6704-10GE module may report incorrect traffic levels after 3.4 Gbps of traffic has been exceeded in any one direction.

Conditions: This symptom is observed on a Cisco 7600 series that runs Cisco IOS Release 12.2(33)SRB1.

Workaround: Apply a policy map on the interface to provide correct reporting of the traffic levels.

If instead losses are real:

first of all I would enable flow control on both ends of the links so that by sending pause frame one side can signal that is too busy.

You see there are a lot of input drops I would check if there are a lot of packets that are process switched (cef punt ) this could explain what you see. If so they would wait in the hold-queue and then you see a lot of input drops 78174753 and overrun 39126414

Note also:

WS-X6704-10GE ships with WS-X6700-CFC installed unless ordered with WS-F6700-DFC3BXL or WS-F6700-DFC3B.

http://www.cisco.com/en/US/docs/routers/7600/Hardware/12.2SR_supported_hw/7600_hwd.html#wp1304068

performance can be better with a DFC 3BXL check what submodule you have installed

Hope to help

Giuseppe