RE: GPRS Tunnel Protocol (GTP)

Xiaobao -

> 4) Mobile IPv6, however, is expected to have some impact on 
> some  operations on GPRS/UMTS, especially on IPv6 (only) IMS. 
> This is  because Mobile IPv6 runs on an end-to-end basis, 
> i.e, an IPv6 GPRS/UMTS terminal can activate MIPv6 with its 
> peers without the knowledge of the intermediate GPRS/UMTS 
> systems. We have done some analysis. The details can be found 
> in an I-D located at 
> http://www.ietf.org/internet-drafts/draft-chen-mobileip-packet
> -fitlering-xc-01.txt
> .

>From this draft:

"4.1.2 The Case of Route Optimisation when the CN is mobile
...
 
   A typical example is the case when  the GSSN uses ingress 
   filtering for selecting the UMTS sessions.Although the packet sent 
   from the mobile CN to the MN has the  "Home Address Destination 
   Option" containing its Home  address[1], a gateway node as 
   an intermediate node operating standard IPv6 does not read it. 
   This will have some serious implications such as the disruption of 
   existing live sessions."

"5. Requirements on Inter-working Mobile IPv6 with Packet Filtering

   The following requirements are recommended for a gateway node that
   performs source address and/or destination address based packet
   filtering:

   * A gateway node running standard IPv6 should not be required to
     change to support packet filtering function.

   * The policy control functions for packet filtering such as the PCF
     should not be aware of the mobility control based on mobile IP."

"6.1.2 The Recommended Practice in case of Route Optimisation

   For a CN communicating to a MN using route optimisation
   to send packets directly to the MN, the CN should insert its IP
   address in the Hop-by-Hop Options Header. In the case where the CN
   is a mobile itself and away from its network, the CN should insert
   its Home IP address in the Options filed in the Hop-by-Hop Options
   Header."

Unless I'm misreading this, it sounds like you are recommending that the
issues that MIPv6 route optimization introduces to GPRS packet filtering
(performed by gateway nodes, part of the GPRS infrastructure) should not
be fixed on the GPRS gateway nodes, but instead should be fixed in all
MIPv6 CNs (i.e. all non-GPRS servers on the IPv6 Internet,
MIPv6-capable, now forced to implement this brand new GPRS-specific
Hop-by-Hop Options Header requirement solely to avoid needing to upgrade
the GPRS gateway nodes). IMO this is the wrong recommendation... you
should fix this problem in the GPRS gateway nodes.

Thanks.
- Ed Remmell
Elmic Systems, USA
http://www.elmic.com

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