Subject: Re: [mobile-ip] Some questions on Hierarchical MIPv6

From: James Kempf <[email-masked]>
Date: Sat, 17 Mar 2001 11:02:14 -0800 (PST)

>This is to say that RegReg can come up with another autoconfig scheme for the 
routing
>hierarchy that decouples BU signalling and caters for
>single points of failures. This can also be expressed as "we are supplying a 
detailed
>supplement to the draft that solves this problem" which is
>just as good as your statement. What we need to make sure is understand that 
everything
>comes at a price. Complex protocol and signalling for
>really awkward mobility situations that can become the norm, or protocol 
simplicity for
>the base case and addition of optimization that again
>bring complications to the signalling design...I cannot see a clear cut choice 
to any of
>the two options.
>
>I feel that the group would benefit infinetely if the specs merge...
>

I'd like to second this.

But first, I think there needs to be some agreement on requirements.

		jak

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From: "Eunsoo Shim" <[email-masked]>
Date: Sun, 18 Mar 2001 01:11:07 -0500

I also think that agreed requirements will help developing the  protocol
tremendously.
Unfortunately I don't know all the detailed history of the WG and thus I
don't know what requirements were used as the base for the existing drafts.
I'd like to list several requirements that seem to me a sort of minimal
ones.

1) Localizing signaling for intra-domain handoffs
- Minimizing signaling traffic to HA or CN for intra-domain handoffs
2) Minimizing overhead on air-interface and MN
3) Reliability
- Capability to provide connectivity continously to existing or new MNs
visiting the domain in the case of intermediate node failures
(the intermedia node would be MAP, GFA, RFA, etc.)
4) Minimizing service disruption period in the case of intermediate node
failures
5) Scalability
6) Security

I'd like to point several issues for each proposal (RR, HMIP).

RR:
It has been pointed out that the existing RR draft has a serious problem in
reliability.
I read in multiple emails that there could be a solution for relaibility for
the RR proposal as a kind of dynamic configuration protocol.
I'd appreciate if the protocol is presented.
I'd like to add that actually we proposed a solution recently (Reliable and
Scalable Mobile IP Regional Registration) if it could be helpful at all.
I read some people are interested in applying IPv6 anycast for RR. I will
have to think about how it helps reliability of RR for MIPv6. Anyway I still
wonder about RR for MIPv4. What kind of solution is being pursued by the
authors of the draft?

HMIP:
In my understanding, the HMIP proposal allows redundant or multiple MAPs
covering a certain spot (or cell). I see several issues in HMIP regarding
it. I assume a MN registers with only a MAP at a time.
- Overhead to the air-interface due to MAP option advertisement
As the number of MAPs increase, the overhead becomes larger.
- Overhead to the MN
MN needs to monitor the MAP option advertisement continously to know whether
the MAP is alive even when the MN has not moved its location
- Connectivity recovery time
The MN needs to wait for the MAP option advertisements and then do
re-registration to a new MAP, HA and/or CN. The MN should know the MAP
option advertisement period and wait for a certain timeout period to find
out the failure of the MAP. Obviously the advertisement period is related to
the overhead to the air-interface and thus it is not easy to reduce the
period.

I'd appreciate any answer or correction on my understanding of the drafts.

Eunsoo