1.4.a IPv4 and IPv6 PMTU – CCNP Route Exam v2.0 (300-101)
In this video I discuss how IPv4/IPv6 Path MTU works. I demonstrate how to modify the MTU size in GNS3 and once again use the pipe/rock analogy. YouTube is pretty intelligent with selecting thumbnails lol
Notes:
I forgot to mention you can use the ip tcp path-mtu-discovery global configuration command to enable Path MTU Discovery for connections initiated by the device when the device is acting as a host. Be mindful when modifying the MTU because this can cause an issue on a link connecting two OSPF neighbors. Remember MTU sizes MUST match between the routers or they won’t become neighbors unless you ask the router to disregard this. You can configure OSPF to ignore MTU sizes like this:
interface FastEthernet1/0
ip ospf mtu-ignore
References:
Duan Lighfoot’s Lab Everyday Shirts
http://a.co/d/6xf1kE1
RFC 1191
https://www.ietf.org/rfc/rfc1191.txt?number=1191
Article on MTU size:
ipv4
