Subject: Routing Header in IPv6

From: "Anjanish P" <[email-masked]>
Date: Thu, 4 Sep 2003 16:56:48 +0530

Hi All,

One statment in RFC 2460 Looks contradictory, to the behaviour of Routing
Header processing.

One Page 05. Sections 4. The below para says :
---------------------------------------------
"With one exception, extension headers are not examined or processed
   by any node along a packet's delivery path, until the packet reaches
   the node (or each of the set of nodes, in the case of multicast)
   identified in the Destination Address field of the IPv6 header."

Followed by para as below:

"   The exception referred to in the preceding paragraph is the Hop-by-
   Hop Options header, which carries information that must be examined
   and processed by every node along a packet's delivery path, including
   the source and destination nodes. "

------------------------------------------------

Section 4.4 of the RFC specifies that Routing header, need to be processed
by the intermediate nodes.

Since, section 4.4 is correct, how can statement of section of 4.0 be
correct ???

Please clarify.

Thanks in advance for your response.

Regards,
Anjanish

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From: "Suresh Krishnan (QB/EMC)" <[email-masked]>
Date: Thu, 4 Sep 2003 09:25:31 -0500

Hi Anjanish,
	There is no contradiction. The intermediate nodes which are to be traversed will be listed as the destination address in the IPv6 datagram in the repsective segments and hence they can process the Routing header. 

Say H1 wants to talk to H2 using the route H1->R1->R2->R3->H2. In the segment between H1 and R1 the IPv6 source address will be H1 and the IPv6 dest address will be R1 (and not H2) the segments left would be 3 and the addresses in the type 0 routing header will be R2,R3 and H2. As this datagram is addressed to R1 it will examine the Routing Header. The same procedure is followed between R1 and R2 and so on until the segments left becomes 0.

Regards
Suresh

-----Original Message-----
From: Anjanish P [mailto:[email-masked]]
Sent: Thursday, September 04, 2003 7:27 AM
To: [email-masked]
Cc: [email-masked]; [email-masked]
Subject: Routing Header in IPv6

Hi All,

Please clarify.

Regards,
Anjanish