Re: MN behaviors to uplink data packets during a handoff

Hi Jay and all,

Thank you very much for your reply.

According to your comments, can I think this way that the disruption to
uplink stream caused by a handoff is largely depending on the link layer
technology and the Mobility Agent (or the administrative domain) behaviors?
That is,

For example, as far as I know, Mobile Nodes in WLAN make sure there is an
Access Point reachable before everytime they send out a frame. In this case,
even if the MN loses contact with any AP for some time, IP packets would not
be lost, instead, they queue up at the link layer and wait for the link data
frame to be sent out. (?)

When the MN is in registration process with a new FA, it sends out data
packets to the new FA as long as it knows the FA's MAC address. Whether to
offer service to the unauthorized MN (at least before the successful
registration reply comes back) depends on the policy the new FA (or the
admistrative domain it belongs to) deploys. If it does not, uplink data
packets are discarded by it during the registration process. If it does
offer service, there could be no uplink data packets lost in WLAN. (?)

However, it is not WLAN, things might be different. (?)

Regards,
Jee


----- Original Message -----
From: "Jay J Lee" <[email protected]>
To: "Ji Zhang" <[email protected]>; <[email protected]>
Sent: Thursday, July 24, 2003 3:59 AM
Subject: Re: [mobile-ip] [Mobile IP] MN behaviors to uplink data packets
during a handoff


> Hi,
>
> I believe these are all implementation time decisions.
>
> For #1, if you are talking about MIPv4, what is happening within the IP
> layer should not affect the link layer.  If it still has upper layer
> packets to send out it will continue to do so.  The link/MAC layer does
not
> and should not know what happens at the other layers other than the
packets
> it receives from them.  Although with MIPv6 there are proposals for
> inter-layer communications.
>
> For #2, the OPNET MIPv4 simulation model, for example, keeps sending the
> data packets to the last known agent (HA or FA) on the last known good
> interface whether it is lost or in the process of registration.  This
> decision was made because once you start queueing packets and managing
> them, the implementation becomes expensive considerably in the simulation
> domain as well as for the OSes in the real devices.
>
> Hope this helps, - Jay
>
>
> At 09:37 PM 7/23/2003 +0100, Ji Zhang wrote:
> >Hi all,
> >
> >Could anybody offer me some instructions on the behaviors of a Mobile
Node
> >to
> >uplink (MN-->FA) data packets during a handoff?
> >
> >For example,
> >1. when the MN loses link contact with the old FA (before getting an
agent
> >advertisement), are all uplink data packets stored up at the link layer?
> >2. when the MN is aware of agent advertisements are missing, at the same
> >time it sends an agent solicitation, should it stop sending data packets
> >until
> >it gets an agent advertisement (or even until the registration is
> >successful)?
> >
> >Many thanks,
> >Jee
>
>