From: ccie2be (ccie2be@nyc.rr.com)
Date: Sat May 28 2005 - 17:05:12 GMT-3
Thanks Scott for getting back to me.
I think, however, we're not on exactly the same page.
So, let me try to explain the issue differently.
When a MN goes to a foreign network, the MN KNOWS it's on the foreign
network because it hears the IRDP announcements made by the FA. In fact,
IRDP is required to be configured on the FA.
Now, when the MN returns to it home network, how does the MN know its on its
how network and not some other foreign network. After all, the HA does NOT
have to be configured with IRDP.
Also, the HA needs to know immediately when MN returns to its home network
since it would not be good if the HA is still tunneling packets to the MN
when the MN is NOT away.
So, without IRDP configured on the HA, how does the MN and HA know the MN
has returned to the home network?
Thanks again, Tim
PS: What's wrong with you? What are doing on GS on a 3 day holiday
weekend? As for me, I'm still trying to become a ccie but you already have
4 of them, so what's your excuse? Are the issues I raise so interesting and
provocative its difficult to rip yourself away? :-)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Scott Morris
Sent: Saturday, May 28, 2005 2:43 PM
To: 'ccie2be'; 'Stephen Fisher'
Cc: ccielab@groupstudy.com
Subject: RE: Mobile IP and IRDP
During the registration process, there is also a time mechanism involved.
So, you register (can even be AAA-driven) and for that time period you are
in the mobility binding table.
Bear in mind that there is a software that resides on the client PC to
handle this registration and stuff as well!
But after the time period, especially if not renewed (much like DHCP lease)
then the mobility binding (/32) expires and defaults back to wherever the
route normally exists.
HTH,
Scott
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Saturday, May 28, 2005 1:16 PM
To: swm@emanon.com; 'Stephen Fisher'
Cc: ccielab@groupstudy.com
Subject: RE: Mobile IP and IRDP
Thanks, Scott.
But, do you know what mechanism is used when a MN returns to its home
network to inform the MN that it is now back on its home network?
Since IRDP doesn't have to be configured on the HA, there must be some way
MN learn this so that they can deregister their binding on the HA.
Tim
-----Original Message-----
From: Scott Morris [mailto:swm@emanon.com]
Sent: Saturday, May 28, 2005 1:08 PM
To: 'Stephen Fisher'; 'ccie2be'
Cc: ccielab@groupstudy.com
Subject: RE: Mobile IP and IRDP
IRDP is done on the FA. The MN will wander around a network, and as it
wanders on someplace that is not its own native network it will need to know
about the gateway to get out. That's the problem that IRDP solves.
The HA simply sits around and waits to hear /32 CoA announcements from the
FA regarding stations that are wandering.
HTH,
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Stephen Fisher
Sent: Saturday, May 28, 2005 12:44 PM
To: ccie2be
Cc: ccielab@groupstudy.com
Subject: Re: Mobile IP and IRDP
On Fri, May 27, 2005 at 04:40:04PM -0400, ccie2be wrote:
> Now, it makes sense to me that IRDP needs to be configured on the FA
> router. It also seems to me that IRDP should also be configured on the
> HA interfaces where MN exist so that MN's know they are on the Home
> Network.
>
> But, in the examples on the Doc-CD and in the Cisco Press, IRDP isn't
> configured on the HA.
>
> Do you know why that is?
That's a good question.. the way I understand it, the MN knows it is on its
home network when its assigned address (such as through DHCP) matches its
usual IP address. The Cisco Press Mobile IP book also mentions comparing
its usual address to the prefixes received in IRDP announcements so now I'm
not sure either.
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