ping loss on n3k but no error under interface

[chyoon]

Hi experts,

I'm facing a problem regarding loss of ping packets when i do ping test from nexus3k to another nexus3k connected directly.

however there is no error counters on the interfaces on both of devices.

the ping failutre is occurring only whenever i do ping test with a large number of ping packets.

I don't see the ping loss symptom with default ping test (default ping test is 5 packets).

H/W : N3K-C3548P-10G

S/W : 5.0(3)A1(1)

nexus3k# ping 1.1.1.2

PING 1.1.1.2 (1.1.1.2): 56 data bytes

64 bytes from 1.1.1.2: icmp_seq=0 ttl=254 time=2.732 ms

64 bytes from 1.1.1.2: icmp_seq=0 ttl=254 time=2.732 ms

64 bytes from 1.1.1.2: icmp_seq=0 ttl=254 time=2.732 ms

64 bytes from 1.1.1.2: icmp_seq=0 ttl=254 time=2.732 ms

64 bytes from 1.1.1.2: icmp_seq=0 ttl=254 time=2.732 ms

--- 1.1.1.2 ping statistics ---

5 packets transmitted, 5 packets received, 0.00% packet loss

round-trip min/avg/max = 2.078/2.295/2.732 ms

nexus3k# ping 1.1.1.2 count 1000

PING 1.1.1.2 (1.1.1.2): 56 data bytes

64 bytes from 1.1.1.2: icmp_seq=0 ttl=254 time=2.656 ms

-snipped-

64 bytes from 1.1.1.2: icmp_seq=0 ttl=254 time=2.732 ms

--- 1.1.1.2 ping statistics ---

1000 packets transmitted, 993 packets received, 0.70% packet loss

round-trip min/avg/max = 1.761/2.372/21.372 ms

any comments woule be appreciated.

Regards,

John

[Reza Sharifi · Accepted solution]

Hi John,

That is by design. I have seen the same issue with 7Ks. The Nexus series have CoPP by default and that limits the amount of ICMP traffic that is destine for the control plane.  If you want to run that many pings try this command first and then use ping with count again.

"clear copp statis"

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9402/guide_c07-665160.html#wp9000461

HTH

[chyoon]

Hi Reza,

thanks for the quick response.

I agreed with your option regarding the built-in CoPP configuration on the nexus7k platform.

but the new nexus3k platform has a little bit different operational behavior in terms of CoPP operation in this case.

I'm able to see the limitation on the below link regarding CoPP.

http://www.cisco.com/en/US/partner/docs/switches/datacenter/nexus3548/sw/release_notes/503_A1_2_nx-os.html#wp334987

and i also trid to collect ouptuts, but there was no configuration on running and startup on n3k.

nexus3k# show running-config copp all

!Command: show running-config copp all

!Time: Wed Feb 27 04:28:43 2013

version 5.0(3)A1(1)

nexus3k# show startup-config copp all

!Command: show startup-config copp all

!Time: Wed Feb 27 04:28:49 2013

!Startup config saved at: Sat Feb 23 08:58:04 2013

version 5.0(3)A1(1)

nexus3k# show copp status

Last Config Operation: None

Last Config Operation Timestamp: None

Last Config Operation Status: None

Policy-map attached to the control-plane: None

I heard that the 'static CoPP' configuration on the nexus platform which looks like build-in CoPP so we can't see it on the running or start-up configuration, but built-in CoPP has always been working.

what do you think..? any idea on this..?

thanks in advnace,

John