[j-nsp] Strange Latency on EX-4248t virtual chassis

Shane Ronan sronan at fattoc.com
Mon Nov 16 14:26:57 EST 2009


Hoping someone here can help me with the issue I describe below. I know 4u seems like a VERY small amount of latency, but it's an issue for our system.

I have a set of five ex-4248t switches, connected via virtual chassis such that no two switches are more then two hops apart, as show below.

1 to 2
2 to 4
4 to 5
1 to 3
3 to 5

I have host A connected to switch 1, and host B connected to switch 2, my latency  is 27u, but when I move host B to switch 3, the latency goes up to 31u, these numbers are 100% repeatable, so it's not just some simple variation in a one time test.

This seems odd, since switch 2 and 3 are both a directly connected to switch 1.

What is even more odd, is the farther away from switch 1 you get numerically, the higher the latency gets (1 to 4 is 34u, and 1 to 5 is 37u)

This is a huge issue for us, as we cannot connect hosts to anything other then switch 1 and 2 currently due to the increase in latency.

Any input from the group would be appreciate.


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