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

[Shane Ronan]

Interesting, so you are saying it doesn't always take the shortest path?


On Nov 17, 2009, at 1:05 AM, <techtalm at gmail.com> <techtalm at gmail.com> wrote:

> Who is the RE and who is the Backup RE?
> Although SW 1 is connected directly to SW2 and SW3 it goes to one of them
> through all the other switches, I think it is SW3 which SW1 goes all the
> round.
> 
> mtc
> 
> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net
> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Shane Ronan
> Sent: Monday, November 16, 2009 9:27 PM
> To: juniper-nsp
> Subject: [j-nsp] Strange Latency on EX-4248t virtual chassis
> 
> 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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