High latency in a DC LAN

[Ruslan Khusnutdinov]

Hello mates,

We have a high latency issue when ping virtual hosts through Core switch. We have Core VSS on Cat6506 connected to Nexus 5548 where virtual hosts connected.

What do we see :

|                                      WinMTR statistics                                   

|                       Host              -              | Sent  | Recv | Best | Avrg | Wrst | Last |

|------------------------------------------------|-----    -|---   ---|----   --|------|-----   -|------|

|                               10.0.21.1 -       0 | 4058  | 4058 |        0 |    2 |  291 |    0 |

|                             10.0.26.202 -    0 | 4064  | 4064 |         0 |    0 |   19 |    0 |

This test was done from host in vlan 21 to device in vlan 26. All packets was delivered without lost, but the worst delay 291ms on default gateway. All vlans are terminated on VSS Core. And the situation is the same for all vlans.

Core connects to Nexuses by 4x10 Gb interfaces and there is no high utilization nor errors on them. CPU utilization is less than 50%  in peaks but usually 10-12%.

Cisco IOS Version 12.2(50r)SYS2. 

How can I troubleshoot this?  any ideas? Thanks in advance

[devils_advocate]

Hi

Looking at the results shown above, the average response seems to be 2ms (assuming I am reading it correctly). 

Are you having issues with these hosts or have you just noticed the odd high ping time?

If the average is 2ms then it can't be hitting 291ms very often.

Thanks

[glen.grant]

   If you are pinging the 6500 ,  it relegates ping response to a low priority so if its busy doing  something else ping response goes to the bottom of the heap so i wouldn't worry much about that .