Subject: [Mip4] Query: What should the TTL value be if request is sent to All Mobility Agents multicast address with reverse tunnel bit set?

From: manju_shivaji <[email-masked]>
Date: Wed, 19 Oct 2005 17:00:43 +0530

Hi, 

I have one implementation doubt regarding the TTL value in the registration
request received at Foreign Agent

.

The mobile IP RFC 3344 says in section 3.6.1.1,

IP Time to Live:

      -  The IP TTL field MUST be set to 1 if the IP destination address

         is set to the "All Mobility Agents" multicast address as

         described above.  Otherwise a suitable value should be chosen

         in accordance with standard IP practice [38].

Now Reverse Tunnel RFC 3024 says in section 3.2.

In Registration Requests sent by a mobile node, the Time to Live

   field in the IP header MUST be set to 255.  This limits a denial of

   service attack in which malicious hosts send false Registration

   Requests.

What if these two cases combine? ie What should the TTL value be if the
request is sent to all mobility agents multicast address with reverse tunnel
bit set?

Should the foreign agent verify that IP TTL value is 1 if the received
request has "All Mobility Agents" multicast address as the destination
address? 

Regards,

Manju.

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---

From: "Kent Leung \(kleung\)" <[email-masked]>
Date: Thu, 20 Oct 2005 09:12:58 -0700

Hi Manju.  When the T bit is set in the RRQ, then the IP TTL MUST be 255
in accordance to RFC 3024.
 
Kent

________________________________

	From: [email-masked] [mailto:[email-masked]] On
Behalf Of manju_shivaji
	Sent: Wednesday, October 19, 2005 4:31 AM
	To: [email-masked]
	Subject: [Mip4] Query: What should the TTL value be if request
is sent to All Mobility Agents multicast address with reverse tunnel bit
set?

	Hi, 

	I have one implementation doubt regarding the TTL value in the
registration request received at Foreign Agent

	.

	IP Time to Live:

	      -  The IP TTL field MUST be set to 1 if the IP destination
address

	         is set to the "All Mobility Agents" multicast address
as

	         described above.  Otherwise a suitable value should be
chosen

	   field in the IP header MUST be set to 255.  This limits a
denial of

	   service attack in which malicious hosts send false
Registration

	   Requests.

	What if these two cases combine? ie What should the TTL value be
if the request is sent to all mobility agents multicast address with
reverse tunnel bit set?

	Should the foreign agent verify that IP TTL value is 1 if the
received request has "All Mobility Agents" multicast address as the
destination address? 

	Regards,

	Manju.