On 31/05/2016 20:13, Xuxiaohu wrote: > > >> -----Original Message----- >> From: Brian E Carpenter [mailto:brian.e.carpen...@gmail.com] >> Sent: Tuesday, May 31, 2016 4:46 AM >> To: Joe Touch >> Cc: joel jaeggli; Xuxiaohu; Fred Baker (fred); Wassim Haddad; >> int-area@ietf.org >> Subject: Re: [Int-area] Call for adoption of draft-xu-intarea-ip-in-udp-03 >> >> And being pedantic... >> On 31/05/2016 06:12, Joe Touch wrote: >>> >>> >>> On 5/29/2016 4:23 PM, joel jaeggli wrote: >>>>>> I.e., you MUST support source fragmentation at the ingress at the >>>>>> outer >>>>>> IPv6 layer (because UDP doesn't have support for fragmentation and >>>>>> reassembly). If you make this requirement, you can handle IPv6 over >>>>>> the tunnel. >>>> Yeah I don't support it for this reason. getting IP fragments back >>>> together in the same place a reassembled is hard is in some cases >>>> especially when you hash. (see frag drop) given alternatives that >>>> better address such situations it seems hard to justify. >>> >>> If you intend to support recursive IP tunneling* and believe that IP >>> has a minimum MTU, then you have to accept reassembly. >> >> If you intend to support recursive datagram tunneling and believe that any >> path >> has a minimum MTU, then you have to accept reassembly. >> >> This is physics, and nothing to do with design details. >> >> (Something I discovered in about 1983, when implementing OSI/CLNP at CERN >> over a homebrew network with 128 byte packets.) > > Reassembly on the tunnel egress may be acceptable at that old time. However, > due to the considerable improvement in network bandwidth capability, the > practice acceptable at the old time may have become outdated today.
I don't understand what network capacity has to do with the physical and mathematical fact that packets larger than N bytes will not fit into a packet limited to N bytes. That was true in 1983 and will still be true in 2083. Brian > See the MAP implementation experience shared by Ole recently. > > Xiaohu > >> Brian >> >>> >>> Joe >>> >>> * where "recursive IP tunneling" is IP in [zero or more other >>> protocols] in IP. >>> >>> _______________________________________________ >>> Int-area mailing list >>> Int-area@ietf.org >>> https://www.ietf.org/mailman/listinfo/int-area >>> _______________________________________________ Int-area mailing list Int-area@ietf.org https://www.ietf.org/mailman/listinfo/int-area
