[c-nsp] strange behavior over MPLS network - remote desktop won't work

Chris Hale chale99 at gmail.com
Sun May 31 19:54:16 EDT 2009

On Sun, May 31, 2009 at 5:22 PM, Sascha E. Pollok <nsp-list at pollok.net>wrote:

> Chris,
>  The mpls MTU over the gige wireless backbone between the POPs was MTU1500.
>> I will change that to 1538 and see what happens.
> try to do the 1500 Byte pings between the PEs with
> DF bit set. I'd rather test the connectivity at
> 1500 bytes before trying to tweak something.
> Also, what kind of FE boards do you use on the 7206?
> I am currently unsure whether e.g. PA-FE-TX support
> larger MTUs needed for MPLS/VPN.

I'm using PA-FE-TX as you guessed.  I have enabled the larger MTUs for MPLS
with mpls mtu 1538 as per others who have successfully used this.

I'm using one of my J2320's (CE router) and found this:

ping do-not-fragment detail size 1473
PING ( 1473 data bytes
ping: sendto: Message too long

ping do-not-fragment detail size 1472
PING ( 1472 data bytes
1480 bytes from via ge-0/0/3.600: icmp_seq=0 ttl=62
time=12.598 ms
1480 bytes from via ge-0/0/3.600: icmp_seq=1 ttl=62
time=14.612 ms

What does that indicate to you?  1472 + VLAN tag plus MPLS < 1500?

Chris Hale
chale99 at gmail.com

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