Sorry - that fired too fast.
RFC 2711 also references RFC 2460, so it was built for the H-B-H
extension header. Also, if you look at RFC 3810 (MLDv2), it also
references the Router Alert Option and says:
All MLDv2 messages described in this document MUST be sent with a
link-local IPv6 Source Address, an IPv6 Hop Limit of 1, and an
IPv6 Router Alert option [RFC2711] in a Hop-by-Hop Options
header. (The Router Alert option is necessary to cause routers
to examine MLDv2 messages sent to IPv6 multicast addresses in
which the routers themselves have no interest.)
So, I still don't understand the Router Alert Option, but I see a
number of places where it is referenced.
[[Spence]]
________________________________
From: John Spence [mailto:[EMAIL PROTECTED]
Sent: Tuesday, November 01, 2005 7:25 PM
To: 'Fred Baker'
Cc: 'ipv6@ietf.org'
Subject: RE: Question about the need for a "Router Alert
Option" (RFC 2711) within a Hop-By-Hop Option Extension Header
(RFC 2460) ...
Thanks for the quick reply. The Router Alert Option (RFC
2711) is dated October 1999. It says "This memo describes a new
IPv6 Hop-by-Hop Option type ", so the Router Alert is designed
for the H-B-H Extension header.
----------------------------------------------------
John Spence, CCSI, CCNA, CISSP
Native6, Inc.
IPv6 Training and Consulting
[EMAIL PROTECTED]
(wk) 206-682-0275
www.native6.com
----------------------------------------------------
________________________________
From: Fred Baker [mailto:[EMAIL PROTECTED]
Sent: Tuesday, November 01, 2005 6:48 PM
To: John Spence
Cc: ipv6@ietf.org
Subject: Re: Question about the need for a
"Router Alert Option" (RFC 2711) within a Hop-By-Hop Option
Extension Header (RFC 2460) ...
one of them sounds like it is redundant. I think
the Router Alert predated the HBH header...
On Nov 1, 2005, at 6:04 PM, John Spence wrote:
Hello;
If the H-B-H
extension header means "all intermediate nodes must look in here
for options to process", why is the "Router Alert" option needed?
As I read the text of the two RFCs, the Router Alert Option is
redundant - just including a H-B-H header means "intermediate
nodes must look at this packet even if it is not addressed to
them", which seems to be the same meaning as Router Alert.
I must be missing
something. Can someone provide a quick answer, or a pointer to
the answer so I can research it myself?
Thanks very much.
John Spence
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