Re: What do you consider acceptable packet / session modification for a network operator?

Am 26.12.2025 um 10:52:48 Uhr schrieb Tom Beecher:

Packet comes in with DF set. Egress interface MTU is too small. ICMP Frag Needed generated, source address is RFC1918 loopback from the router control plane. On the return trip, packet crosses network that (correctly) drops all RFC1918 sourced traffic.

Can't you use NAT (the Cisco ISR devices support nat inside on lo too IIRC) or configure the source address for outgoing router traffic?

This is not a routing problem at all. This is very common.

Indeed, but a filtering problem if routers on the path filter non-public address ranges. -- Gruß Marco Send unsolicited bulk mail to 1766742768muell@cartoonies.org