Re: [6bed4-devel] Tunnel MTU fixed at 1280
zeroconfig IPv6 tunnel
Status: Beta
Brought to you by:
vanrein
From: Timothy B. <tim...@fa...> - 2011-11-30 22:21:53
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On 26/11/11 13:02, Joost Lek wrote: > On Nov 26, 2011, at 1:49 PM, Rick van Rein wrote: > > I don't see a benefit in deviating from the IPv6 protocol here and would say a minimum MTU of 1280 is required. If the MTU is too large, let the v6 layer handle the problem. That could lead to a relay reassembling IPv4 packets before forwarding them, the IPv6 MTU should be limited to IPv4 MTU-overhead. The client MUST perform IPv4 MTU discovery reliably, this is difficult given some NAT routers don't issue ICMP Fragmentation Needed errors, but instead adjust the TCP MSS. The route from the relay to client is more difficult, IPv4 MTU discovery by the relay is impossible, and there is a risk that packets from different relays will have different identification fields and mixed up on reassembly. Perhaps the client could respond to IPv4 fragments with IPv6 Too Big. |