Hello, after reading previous post about NAT, i don't have very clear how to resolve my problem.
I'm using a MPLS-VPN to connect different sites to a central site providing internet access with a PIX (old device, PIX 520 6.1), anf i've found those known problems when using PAT (users not nagating in www.hotmail.com and more)
USER - CE - PE - MPLS - PE - PIX - INET
i have configured every link in the MPLS path with MTU 1516 and tag-switching mtu 1512. And links over pure IP with MTU 1500