What do the "Packet Too Big" ICMPv6 messages I see in packet captures mean?


Article ID: 168581


Updated On:


CacheFlow Appliance Software ProxySG Software - SGOS


The "Packet too big" message is meant to be a PMTU discovery mechanism of IPv6. In IPv6 networks, fragmentation doesn't happen on the router. Rather, the source, (the ProxySG or CacheFlow appliance in this case) has to adjust the packet length according to the MTU of the path. 



If a router returns a "Packet too big" message to the CacheFlow or ProxySG appliance, the appliance will respond by automatically reducing the packet length and sending it again.No configuration or remediation is required.