Ethernet Switches & Routers

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Occasional Contributor
Posts: 5
Registered: ‎05-19-2010

intermittent increase in latency traversing MLX MCT cluster

attached is a highlevel diagram.

there are multiple fesx switches attached to the vdx cluster.

the MLX MCT is doing all the inter-vlan routing

when servers attached to the FESX ping between themselves or ping their default gateway I see every now and then an increase in latency from submillisecond reply to as high as 20ms.

any reason for this?

I also see this behaviour when pinging between the two mlx's.

Frequent Contributor
Posts: 117
Registered: ‎07-26-2010

Re: intermittent increase in latency traversing MLX MCT cluster

Hi Erick,

what about the CPU on the switches?

especially on MLX:

show cpu lp?

or on the FESX:

show cpu?

Is the traffic sometimes flooded as unknown unicast?

Cheers

Karl

Occasional Contributor
Posts: 5
Registered: ‎05-19-2010

Re: intermittent increase in latency traversing MLX MCT cluster

CPU on MLX is low and does not waiver much. I haven't seen it over 3percent yet.

SLOT  #:          LP CPU UTILIZATION in  %:
               in 1 second:  in 5 seconds:  in 60 seconds: in 300 seconds:
     1:        1             2              1               1 

on the FESX, it is a constant 1percent.

as for unicast flooding. I see the mac in the cam table (for the default gateway) since that is where the first hop is. i don't see this behaviour on servers that do not flow via the MLX cluster, servers on the same vlan even between different fesx's.

Also, in the diagram there are two upstream devices. a load balancer and a mlx. these are connected via a point to point ve and I see the same issue on those links.

interestingly enough from the upstream mlx to an adjacent device, I do not see this behaviour.

Super Contributor
Posts: 1,087
Registered: ‎12-13-2009

Re: intermittent increase in latency traversing MLX MCT cluster

Hi Erick,

     I would hightly recommend that for this one to contact the TAC and log a case.

Thanks

Michael.

Contributor
Posts: 37
Registered: ‎11-07-2010

Re: intermittent increase in latency traversing MLX MCT cluster

Any solution to the problem?

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