JJ Angleton wrote: > > If you've set the flags in the IP header to not allow > fragmentation, and then you pass through in interface with a > smaller MTU, what happens?
When a router attempts to forward an IP packet onto an interface where the MTU is smaller than the packet and the Don't Fragment bit is set, the router sends back an ICMP Message: Type = 3 = Destination Unreachable Code = 4 = Fragmentation was needed and the Don't Fragment bit was set. The router also drops the packet. > > By the way, in a related question - I've looked all through the > Cisco website and can't find what the standard MTU is for Frame > Relay. I found this in RFC 3090: To avoid packet discards on the Frame Relay interface, the RECOMMENDED default Frame Relay MTU is 1564 based on a PPP default MTU of 1500 bytes. That's the default. You could set it higher, probably, but why bother if the end stations aren't sending anything bigger? _______________________________ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com > > > > > > --------------------------------- > Do you Yahoo!? > U2 on LAUNCH - Exclusive medley & videos from Greatest Hits CD > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=57326&t=57322 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
