Re: [PATCH] IPv6: Fix Prefix Length of Link-local Addresses

On Wed, Oct 09, 2002 at 04:14:14PM -0700, David S. Miller wrote:

I think the change was made because some TAHI test
failed without it, USAGI people is this right?

Most of USAGI changes are of this nature. :-)

There are areas where the TAHI tests expect a certain behaviour when
more than one behaviour is acceptable.

As I recall there is an issue around the behaviour of a packet being
received with a zero length payload.  The TAHI tests seem to expect
one type of ICMPv6 response,  whereas depending upon the value of
next header and the order in which header field validations occur,
two different types of ICMP error can be generated.

Specifically parameter problem identifying the payload field or the
next header field.  I seem to remember this being triggered when a
jumbo header is received by a node that doesn't understand jumbograms.

DF

   From: Derek Fawcus [off-list ref]
   Date: Thu, 10 Oct 2002 00:29:02 +0100

   There are areas where the TAHI tests expect a certain behaviour
   when more than one behaviour is acceptable.

Great, that's what I was trying to find out.

Now I just need to know if this link-local prefix case
is one such issue. :-)

At Wed, 09 Oct 2002 16:24:38 -0700 (PDT),
++ David S. Miller [off-list ref] wrote:

   There are areas where the TAHI tests expect a certain behaviour
   when more than one behaviour is acceptable.

Great, that's what I was trying to find out.

Now I just need to know if this link-local prefix case
is one such issue. :-)

No, there is no test item in TAHI test that supposes
link-local prefix is /64 :-)

The reason we change the prefix length  from /10 to /64 is
following spec and adapting other imprementations.

-- Yuji Sekiya

   From: Yuji Sekiya [off-list ref]
   Date: Thu, 10 Oct 2002 08:41:52 +0900
   
   The reason we change the prefix length  from /10 to /64 is
   following spec and adapting other imprementations.

I think Derek's explanation shows that the specification
allows the /10 behavior.

Also, I suspect that since Derek works for Cisco, some "other
implementations" behave how he describes. :-)

At Wed, 09 Oct 2002 16:45:04 -0700 (PDT),
** David S. Miller [off-list ref] wrote:

   The reason we change the prefix length  from /10 to /64 is
   following spec and adapting other imprementations.

I think Derek's explanation shows that the specification
allows the /10 behavior.

Hmm... we interpret the spec as /64 prefix.

Also, I suspect that since Derek works for Cisco, some "other
implementations" behave how he describes. :-)

I have cisco box which installed IPv6 IOS.
But it defines no prefix length at an interface,

FastEthernet4/1 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::201:64FF:FEA3:ED55

and outgoing interface of routing table is NULL ? :-)

L   FE80::/10 [0/0]
     via ::, Null0, 7w0d

-- Yuji Sekiya