[j-nsp] SSH/Telnet session hanging

[Muhammad Adnan Mohsin]

I have resolved the session hanging issue by lowering the MTU value to
1920 on this router. But the BGP session is now flapping a lot and
it's flapping with both the RRs now. Should I try the tcp-mss option
or should i further play with the MTU value. I lowered the value to
1800 but the flapping was still there. Should I lower this further?

On Wed, Jun 1, 2011 at 1:02 PM, Mark Tinka <mtinka at globaltransit.net> wrote:
> On Wednesday, June 01, 2011 05:19:24 PM Muhammad Adnan
> Mohsin wrote:
>
>> Hi Alexander & rest of the experts,
>> The MTU size in the whole network is set to 4492. But on
>> this router and the router connected to it, the MTU size
>> recommended by the transmission team is 2000. So it's
>> configured 2000 on this router and 1950 is configured on
>> the router that connects to it.
>
> Is this portion of the network different due to limitations
> with the Transmission backbone in this area?
>
>> Can somebody guide me
>> how should i play with the MTU size to resolve this
>> issue.
>
> If you can't raise the MTU on this router to be the same as
> what the rest of your network has, as Alex has already
> recommended, try lowering the MTU on your SSH host, if
> possible.
>
>> BGP also flaps with one of the RRs. I assume that
>> this could also relate to the MTU issue.
>
> You could try setting your TCP MSS to something lower than
> what the link supports, e.g.:
>
>        set protocols bgp tcp-mss 1000
>
> You can keep playing with that until you get to a value low
> enough that gets things working, but doesn't reduce the
> performance of your BGP convergence.
>
> These are band aids. My recommendation would be to find out
> if you can have a consistent MTU across the backbone, if at
> all possible.
>
> Cheers,
>
> Mark.
>