Subject: source routing & multi-homing

From: Alain Durand <[email-masked]>
Date: Fri, 17 Sep 1999 17:42:18 +0200

Trying to be imaginative to find solutions for multi-homing,
I wonder, is there something in the specs to prevent a router
to include a source route option in a transiting packet?

I have a proposal that could use such a mechanism,
but before I go any further to explore it, I would like to know
if there is a one line killer argument against it.

	- Alain.

--------------------------------------------------------------------
IETF IPng Working Group Mailing List
IPng Home Page:                      http://playground.sun.com/ipng
FTP archive:                      ftp://playground.sun.com/pub/ipng
Direct all administrative requests to [email-masked]
--------------------------------------------------------------------

---

From: Steve Deering <[email-masked]>
Date: Fri, 17 Sep 1999 09:25:41 -0700

>if there is a one line killer argument against it.

The two line argument against it is:

    Inserting options into IPv6 packets en-route (or doing anything
    else that increases the packet's length) breaks PMTU Discovery.
    It also breaks the TCP MSS option behavior, unless the inserted
    material is removed before delivery to the destination node(s).

If you want the longer description of exactly how those mechanisms fail,
let me know, and I'll dig through my email archive to find an old message
I once sent that explained that.

The safe way to add additional items to an IPv6 packet en-route is to use
encapsulation.  Encapsulation does not break PMTU Discovery or TCP MSS.

Steve

---

From: [email-masked]
Date: Sat, 18 Sep 1999 01:37:45 +0900

>if there is a one line killer argument against it.

	Unfortunately AH will not work with intermediate insertion of routing
	header.  Also, fragmentation will make thing much trickier.

itojun

---

From: Francis Dupont <[email-masked]>
Date: Sat, 18 Sep 1999 11:19:13 +0200

In your previous mail you wrote:

=> include == add ?

=> this breaks end-to-end security. The correct way to change routing
is to encapsulate the packet (or to use mobility bindings).

[email-masked]