RE: ip in the ran

["tim clifford" <tjc@lacunanet.net>]

jim
comments below, in fact I'm trying to reconcile comments made on the
architecture of a large Internet provider in this mobile discussion;

> I'm not exactly sure what the problem is here, but I don't think
> this has anything to do with whether the RAN uses IP or not.

well, i don't know if its allowed but i suppose i'm fishing for a problem
here.  the dimensioning of an IP-based access network with 10,000 radio
access points seems to exceed various existing Internet deployments.  the
largest dial network has about 2000 access points, and there's only a few
that are this large.  I understand many mobile operators have 10k plus
access points.  I believe the edge router factor (if i'm not misinformed) is
on the order of hundreds of routers, which might be easily exceeded.

>
> Basically, you should be able to configure your subnet topology on
> the edge with a wireless network just like you do with a wired network.
> You group all radio access points under an access router and that
> becomes the edge subnet for the mobiles. Whether the radio access
> points are
> WLAN boxes or BTSs for CDMA/GSM is not relevant. During the network
> configuration, you need to arrange the mapping between access
> routers and radio access points so that routing convergence is
> not adversely affected.

I agree with your points here, but I'd still like to see someone work
through the dimensioning for a "typical" mobile operator and think about
routing implications for what no doubt is going to be a large network.

tim


> -----Original Message-----
> From: owner-more@ops.ietf.org [mailto:owner-more@ops.ietf.org]On Behalf
> Of James Kempf
> Sent: Tuesday, July 24, 2001 12:16 PM
> To: more@psg.com; tjc@lacunanet.net
> Subject: Re: ip in the ran
>
>
> Tim,
>
> >from the misp reqts doc
> >
> >>The ideal  IP access infrastructure is one where the RAN is an
> IP network
> >where
> >>base stations, base station controllers, and mobile terminals
> communicate
> >via IP
> >>protocols. There is considerable ongoing work in this area
> (e.g., the Open
> >RAN
> >>work within the MWIF). Initially, the RAN will be implemented as a link
> >layer
> >>between mobile terminals and the core access network; as a
> second stage the
> >RAN
> >>will become an IP-routed network
> >
> >Has anyone thought about routing and route table convergence in this
> >scenario?  I've spoken to some colleagues that come from the
> legacy Internet
> >space and we discussed the apparent implication of the "edge" of
> the routed
> >cloud (from the core perspective) extending out to, say, the
> BTS.  It seems
> >implied that one's interior routing protocol must now handle a
> much larger
> >domain of addresses.  While I'm sure there are ways to introduce
> hierarchy
> >into this picture and make the routing more palatable, I don't
> believe such
> >an infrastructure has been contemplated on the legacy internet side.
> >
>
> I'm not exactly sure what the problem is here, but I don't think
> this has anything to do with whether the RAN uses IP or not.
>
> Basically, you should be able to configure your subnet topology on
> the edge with a wireless network just like you do with a wired network.
> You group all radio access points under an access router and that
> becomes the edge subnet for the mobiles. Whether the radio access
> points are
> WLAN boxes or BTSs for CDMA/GSM is not relevant. During the network
> configuration, you need to arrange the mapping between access
> routers and radio access points so that routing convergence is
> not adversely affected.
>
> IP RAN is strictly an L2 issue between the access router and the
> radio access points. In networks that run protocols such as
> wCDMA and GSM, IP acts as transport between the BTSs and the
> access routers. It is possible to push IP protocols deeper
> into these networks than the 3Gs currently are discussing. It
> is even possible to do "smart BTSs" where the BTS does macrodiversity
> resolution, but even then the stacks on the connections from the
> other soft
> handoff legs look like:
>
> 		application IP
> 		wCDMA/cdma2000
> 		RAN IP
>
> The exact implications of smart BTSs are still a research topic,
> as is micromobility in this scenario. Perhaps, in the end, the smart
> BTS becomes simply a transparent bridge between both the radio
> and the radio frames over IP on the wire from other smart handoff
> legs.
>
> 		jak
>
>