Subject: RE: [mobile-ip] FW: Changing RS Reply Timing for Mobile IPv6

From: "Hesham Soliman (EAB)" <[email-masked]>
Date: Tue, 8 Oct 2002 18:51:55 +0200

Can't this effect be achieved by recommending that 
MAX_RA_DELAY_TIME be configurable and that an
administrator can pick _one_ router where MAX_RA_DELAY_TIME
can be set to zero? 
 
If so, perhaps the draft can provide such recommendation
(instead of saying that it is out of scope). 
 
Hesham

-----Original Message-----
From: Mohamed Khalil [mailto:[email-masked]]
Sent: Tuesday, October 08, 2002 6:41 PM
To: [email-masked]
Subject: [mobile-ip] FW: Changing RS Reply Timing for Mobile IPv6

FYI 

-----Original Message----- 
From: James Kempf [ mailto:[email-masked] <mailto:[email-masked]> ] 
Sent: Tuesday, October 08, 2002 11:29 AM 
To: [email-masked] 
Subject: Changing RS Reply Timing for Mobile IPv6 

Mohamad Khalil, Brett Pentland, and I just submitted a draft on modifying the RS reply timing: 

http://www.ietf.org/internet-drafts/draft-mkhalil-ipv6-fastra-02.txt <http://www.ietf.org/internet-drafts/draft-mkhalil-ipv6-fastra-02.txt>  

I didn't see an announcement from the drafts editor in this group. 

In summary, the draft amends RFC 2461 to allow at most one router on a link to reply immediately to an RS instead of waiting a random amount of time between 0 and MAX_RA_DELAY_TIME. The router is allowed to reply to at most MAX_FAST_RAS since the last unsolicited multicast is sent. If this number is exceeded, the router rolls over to scheduling a multicast RA as soon as possible. This is intended to avoid DoS attacks on the router.

We believe this amendment will be necessary for achieving good handover performance with standard Mobile IPv6 movement detection. If the mobile node is capable of detecting when the link changes, it can immediately send an RS rather than wait for a multicast RA. This can significantly decrease the amount of time required for movement detection. In addition to theoretical considerations, we have some amount of implementation experience with the existing movement detection algorithm to suggest that the RS reply protocol in RFC 2461 could have moderate to severe performance limiting effects on standard MIPv6 handover.

We would like to have review and discussion of this draft prior to the WG meeting in Atlanta, and finish up the discussion there, with a goal of making this a WG document. The Mobile IP working group will be finishing up the MIPv6 draft soon, and we would like to be able to publish this draft in about the same time frame, so implementors have some guidance.

                    jak 

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---

From: "James Kempf" <[email-masked]>
Date: Tue, 8 Oct 2002 11:01:51 -0700

Hesham,

I think we discussed this when the draft was originally written. There was some
concern on the part of Erik that the router with MAX_RA_DELAY_TME set to zero
would then be open to a DoS attack. In the current design, the router is only
exposed until it runs out of MAX_FAST_RAS. Of course, the attacker can simply
roll over and continue after the RA is multicast, but it does provide some
window of protection.

In addition, there is an issue when the network first comes up (though I would
not expect this to be a common problem) that this router could become
overloaded.

            jak

----- Original Message -----
From: "Hesham Soliman (EAB)" <[email-masked]>
To: "'Mohamed Khalil'" <[email-masked]>;
<[email-masked]>
Sent: Tuesday, October 08, 2002 9:51 AM
Subject: RE: [mobile-ip] FW: Changing RS Reply Timing for Mobile IPv6

> http://www.ietf.org/internet-drafts/draft-mkhalil-ipv6-fastra-02.txt
<http://www.ietf.org/internet-drafts/draft-mkhalil-ipv6-fastra-02.txt>
> In summary, the draft amends RFC 2461 to allow at most one router on a link to
reply immediately to an RS instead of waiting a random amount of time between 0
and MAX_RA_DELAY_TIME. The router is allowed to reply to at most MAX_FAST_RAS
since the last unsolicited multicast is sent. If this number is exceeded, the
router rolls over to scheduling a multicast RA as soon as possible. This is
intended to avoid DoS attacks on the router.
>
> We believe this amendment will be necessary for achieving good handover
performance with standard Mobile IPv6 movement detection. If the mobile node is
capable of detecting when the link changes, it can immediately send an RS rather
than wait for a multicast RA. This can significantly decrease the amount of time
required for movement detection. In addition to theoretical considerations, we
have some amount of implementation experience with the existing movement
detection algorithm to suggest that the RS reply protocol in RFC 2461 could have
moderate to severe performance limiting effects on standard MIPv6 handover.
>
> We would like to have review and discussion of this draft prior to the WG
meeting in Atlanta, and finish up the discussion there, with a goal of making
this a WG document. The Mobile IP working group will be finishing up the MIPv6
draft soon, and we would like to be able to publish this draft in about the same
time frame, so implementors have some guidance.