Hi, this document suggests using PLPMTUD (RFC4821) for GRE tunnels, but it doesn't say anything about how that might be done or for what purposes. I have produced an implementation that does exactly that:
http://linkupnetworks.com/seal/sealv2-0.0.tgz Briefly, the implementation works as follows: 1) If the inner packet is no larger than 1280 bytes minus the length of the encapsulation headers, encapsulate and send without fragmentation. 2) If the inner packet is larger than 1500 bytes but no larger than the path MTU, encapsulate and send without fragmentation. 3) For all other packets, encapsulate and use SEAL fragmentation to break the packets into a size that should be small enough to traverse the tunnel without further fragmentation even if there are other tunnels in the path. At the same time, probe the path to see if packets of this size can be delivered without fragmentation and, if so, discontinue the fragmentation process and send future packets in this size range as whole packets. The procedures are specified in 'draft-templin-intarea-seal', which can be found here: http://tools.ietf.org/html/draft-templin-intarea-seal Thanks - Fred fred.l.temp...@boeing.com _______________________________________________ Int-area mailing list Int-area@ietf.org https://www.ietf.org/mailman/listinfo/int-area
