Re: [RAM] ViP: Anycast ITRs in the DFZ & mobile tunnels

Christian Vogt <christian.vogt@nomadiclab.com> Sat, 16 June 2007 21:31 UTC

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Date: Sun, 17 Jun 2007 00:31:35 +0300
From: Christian Vogt <christian.vogt@nomadiclab.com>
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To: Ved Kafle <kafle@nict.go.jp>
Subject: Re: [RAM] ViP: Anycast ITRs in the DFZ & mobile tunnels
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Ved:

>> In fact, ViP is a proposal for network mobility.  It enables an access
>> network to change ISPs (which is nothing else but a topological
>> "movement") without losing reachability via the original prefix.
> 
> To me, the ViP approach looks similar to the network mobility (nemo) support
> approach being discussed in the IETF nemo WG.  [...]

Absolutely.  This is what I was saying.

> Analogy:
> (1) ViP routers are similar to the mobile network home agents, except that
> the home agents are confined to home networks where as Vip routers may be
> distributed in the Internet.

Actually, ViP routers are confined in the same way as home agents in
that both can only support "home" prefixes that correspond to their
topological location in the Internet.  After all, the idea of ViP
routers is to have them advertise sub-prefixes from their ISP's global
routing prefix so that the sub-prefixes can be aggregated with the
global routing prefix and do not require a separate slot in the DFZ
routing table.

[...]

> There are some well known problems associated with such achor point-based
> approaches, such as increased packet delivery delay, non-optimal routing,
> tunneling overhead, possibilities of single point of faiture, etc. 

Right.  And things don't get better if we do the indirection for all
hosts, not just mobile hosts or hosts moving with mobile networks.

>                                                             To avoid
> these problems, route optimization mechanisms are being investigated in the
> nemo WG. Shouldn't we look for the ID-loc split solutions that avoid such
> problems as much as possible?

Without an intention to prefer either mechanism, I just want to note
that the advantage of ViP is a better transition path, whereas LISP
performs better from the perspective of packet propagation latencies and
fault tolerance.  As a matter of fact, LISP is nothing else but route
optimization (in Mobile IPv6 terms) for ViP.

- Christian



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