How to eleminate the latency and make it equal to <1 or =1ms

banavathkiran · ‎10-07-2013

In my LAN Network, 3750 core and 2960 access switches, in the same VLAN communication the latency is 1ms most of the time in the middle till raise to 2ms to 23 ms.

Why this happens? In the same switch connected PC as getting more latency.

Joseph W. Doherty · ‎10-07-2013

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How are you measuring this latency? Reason I ask, ordinary pings are designed to show reachability not high precision latency measurements. Additionally, because of this, many hosts de-prioritize responding to pings relative to other host activities, especially Cisco devices.

Wilson Bonilla · ‎10-07-2013

Hi

Latency is commonly a consequence of

- High CPU. (show process cpu sorted | ex una) CPU in fixed units should be below 50%

- Input/Output drops. (Show interfaces | inc is up|input packets|CRC|output drops) Switch should be dropping any packet.

- Input/Output errors. (Show interfaces | inc is up|input packets|CRC|output drops) This most likely are layer 1 issues, consider replacing the cables/transceivers if you see errors.

- Spanning-tree loops. (Show spanning-tree detail | inc is executing|from|topology change) TCN counter should not be very high... high amount of TCN in small periords of time are symtomps of l2 loops.

- Hardware failures. (Show post)

Regards.

Wilson B.