Switch Ping – Higher Ping to VLAN Interface Than Other Local Interfaces

pingswitch

I wouldn't call it an issue, but I'm curious.
On our Quanta switch we have a couple of VLANs and vlan interfaces accordingly.

Let's say I'm on a computer in VLAN 10, if I do:

ping 192.168.10.1

with 192.168.10.1 being the VLAN 10 interface on the switch which is set as gateway for the devices in that VLAN, I get responses in range from 1 ms to (sometimes) 28 ms, or even 50 ms etc.
If I ping any other device on the LAN I get responses in less than a millisecond.

Same goes if I go with

traceroute www.stackexchange.com

Here, from the first three hops I get highest delay from my VLAN interface:

  1. gateway (192.168.10.1) 1.601 ms 2.401 ms 2.884 ms

  2. 192.168.xx.xx (192.168.xx.xx) 0.714 ms 0.710 ms 0.749 ms

  3. xx.xx.xx.xx (xx.xx.xx.xx) 0.185 ms 0.224 ms 0.220 ms

Can you give me some ideas about that?

Best Answer

A "L3 switch" will perform the actual packet forwarding (both L2 and L3) using dedicated hardware, but exceptional cases like sending a ping reply or a time exceeded message are normally handled in software by the switch's CPU.

Depending on how powerful and busy the CPU is and how the switch vendor decided to prioritize it's different tasks it may take the CPU some time to get around to processing your packet.

Related Topic