[c-nsp] MPLS MTU

[David Freedman]

I would recommend taking at look at this post I made
  earlier in the year which summarised some responses from the list:

http://puck.nether.net/pipermail/cisco-nsp/2006-June/031765.html

Dave.

Sergio D. wrote:
> Hello folks,
> 
> Some of our customers recently ran into some problems browsing and
> pinging with over 1468. We fixed the browsing issue by adjusting MSS
> on the incoming interfaces. It turns out that our core tag-switching
> interfaces were set at the default 1500 which in turn allowed only a
> 1496 or 1492 IP payload depending on how many labels.
>  So now we are changing the MPLS mtu to 1508, but on Cisco's website
> it mentions the following :
> "Setting the MPLS MTU to a high number can lead to packets being
> dropped on some devices, because the labeled packet is larger than the
> interface physical MTU."
> 
> A lot of our core is FE interfaces, I don't have a way to test this
> before, wouldn't just automatically raise the physical MTU?
> So after raising this an FE MTU goes to 1526? 1508 MPLS + 18 Vlan +
> ethernet header?
> Thanks,
>