Hi, Tammy.
Please check RFC 1981, Chapter 4.
241 Note: A node may receive a Packet Too Big message reporting a
242 next-hop MTU that is less than the IPv6 minimum link MTU. In that
243 case, the node is not required to reduce the size of subsequent
244 packets sent on the path to less than the IPv6 minimun link MTU,
245 but rather must include a Fragment header in those packets [IPv6-
246 SPEC].
In this case, extra 8 bytes mean Fragment header.
And actual test specification is
<http://www.ipv6ready.org/announcement/public_review20071204_p2core.html>.
Perldoc isn't the master.
We are trying to follow the update of master specification,
but sometimes perldoc contains old information.
Please use the specification located at ipv6ready.org.
Regards,
On Wed, 12 Dec 2007 07:18:23 -0700
"Leino, Tammy" <tammy_leino@mentor.com> wrote:
> Hello All,
>
> I reported this issue last Thursday and have not yet heard back from anyone. Do you require further clarification on any points? If so, please let me know.
>
> Best Regards,
> Tammy Leino
>
>
> -----Original Message-----
> From: Leino, Tammy
> Sent: Thursday, December 06, 2007 4:42 PM
> To: users@tahi.org
> Subject: [users:00426] Release 1.5.0b1 Phase-2 PMTU - Test #9 Host Test
>
>
>
> Hello All,
>
> There is a discrepancy in the test procedure diagram and description for this test. The MTU in the Packet Too Big message is actually 56 for this test, and not zero as shown in the procedure diagram.
>
> TN2 TR1 NUT
> | | |
> |-------------------------------------------->|
> | 1.Echo Request | |
> | (1280 octets) | |
> | | |
> |<--------------------------------------------|
> | 2.Echo Reply | |
> | (1280 octets) | |
> | | |
> | +--------------------->|
> | | 3.Packet Too Big |
> | | (MTU 0) |
> | | |
> |-------------------------------------------->|
> | 4.Echo Request | |
> | (1280 octets) | |
> | | |
> |<--------------------------------------------|
> | 5.Echo Reply | |
> | (1288 octets) | |
> | | |
> v v v
>
> Also, can someone please explain to me why the NUT would echo 1288 bytes when it receives only 1280 bytes? I am referring to #4 and #5 of the above diagram.
>
> I am having trouble understanding why this test expects the NUT to fragment the echo reply when the packet size is equal to the IPv6 minimum link MTU. We do not fragment until we reach the link MTU of 1500. Even if we set the link MTU to 1280, the IPv6 minimum link MTU, we should not fragment a 1280 byte echo reply packet. I'm sure I am overlooking something here. Your advice is greatly appreciated.
>
> Best Regards,
> Tammy Leino
>
>
------------------------------------------------------------------------
Yukiyo Akisada <akisada@tahi.org>