Subject: RE: [Mip4] Minor issue with MN advertisement sequence number handling

From: "Arun SG" <[email-masked]>
Date: Mon, 26 Mar 2007 11:10:43 +0530

This takes care of the control plane and maybe one additional line in
data plane is needeed too? Below is an edited version of Bjorn's
original sequence below: 
 
1. FA starts
2. FA sends advertisement with sequence number 0
3. MN registers via FA 
4. MN sends packet to FA for tunneling, and as per section 4.2.2. ["
The foreign agent MUST route datagrams it receives from registered
mobile nodes....."], the FA starts tunneling packets.  
5. FA restarts and assuming a stateless FA, has no knowledge of prior
registrations.
6. FA sends advertisement with sequence number 0 
6.a The MN has continued to send packets as per its original
registration. Should there be an addition line in section 4.2.2 , para
3, stating that the datagram from unregistered MN's must be silently
discarded? Such a description exists in the reverse path towards the MN.
7. Sequence number is equal to, not less than, previous sequence number.
MN does not register. Now assuming that the minor change below is
accepted, MN will register, and step below in original scenario will not
happen.
8. MN sends packet to FA for tunneling, but MN is not registered to FA
(since the FA restarted after the registration), so the FA does not
tunnel the packet to the HA. This will be the case until the
registration expires.

Thanks,
Arun

-----Original Message-----
From: Henrik Levkowetz [mailto:[email-masked]] 
Sent: Saturday, March 24, 2007 1:50 PM
To: Bjorn Andersson
Cc: [email-masked]
Subject: Re: [Mip4] Minor issue with MN advertisement sequence number
handling

on 2007-03-23 12:17 Bjorn Andersson said the following:
...
> 
> Yes, this is exactly what I am saying. The time period between the two

> first advertisements. If the FA advertises once per 30s then the FA 
> should not be restarted for 30s or MNs may lose their connection.
> 
> It's a minor issue, but has already caused confusion in a real life 
> setup (that's how I noticed it). So can't we just change the text to 
> "less or equal to" ? Or are there protocolwise any negative 
> implications of changing the text?

The change looks good to me.  Good catch.

	Henrik

-- 
Mip4 mailing list: [email-masked]
    Web interface: https://www1.ietf.org/mailman/listinfo/mip4
     Charter page: http://www.ietf.org/html.charters/mip4-charter.html
Supplemental site: http://www.mip4.org/

---

From: "Bjorn Andersson" <[email-masked]>
Date: Thu, 29 Mar 2007 10:07:05 +0300

Hi.

> data plane is needeed too? Below is an edited version of Bjorn's
[...]

> discarded? Such a description exists in the reverse path towards the MN.

If I understood you correctly you would like to change 4.2.2. para 3
to something like:

   The foreign agent MUST route datagrams it receives from registered
   mobile nodes and MUST silently discard datagrams it receives from
unregistered mobile nodes.

Adding this restriction may prevent the FA from acting as a normal
router as well, so I feel that would be a little bit too restrictive.
It should be up to the operator policy which packets the FA forwards.

  Bjorn