(usagi-users 02533) ICMPv6(Packet too big)

["村瀬 将" <murase@xxxxxxxxxxxxxx>]

Hi.

I found BUG of ICMPv6(Packet Too Big) in USAGI STABLE RELEASE 4.1.
I think so.


It is an TEST of IPsec(tunnel mode) by the following connections.
(Ref,,Chapter 3.2 Tunnel Mode on USAGI IPsec document(in www.linux-ipv6.org))

HOST1-eth0------eth0-SG1-eth1===========eth1-SG2-eth0------eth0-HOST2
                          |<-- tunnel -->|

MTU of all is 1500Byte.

The IPv6 Packet of 1500 Byte is sent from HOST1 to HOST2 via SG1.

This pakect is transformed data in SG1.
This transform is addition of tunnel header and ESP header.

HOST1 receive The ICMPv6's error message from SG1.
This error message is Packet Too Big(type 2).
and then MTU of the next-hop link is 1460 Byte.

This 1460Byte is incorrect.
I think that correct value is 1430Byte.
Because sum of tunnel header and ESP header is 70Byte over.
( new IPv6 Header (40Byte) + ESP header (30 ~ 37 Byte) )

How about you?


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電話番号が変わりました。2003/05/19