L3 consequences of WLAN offload in cellular networks (was - endless DHCPv6 thread)

Cameron Byrne cb.list6 at gmail.com
Fri Dec 30 08:34:32 CST 2011


On Dec 30, 2011 9:16 AM, "Alexander Harrowell" <a.harrowell at gmail.com>
wrote:
>
> In the DHCP v6 thread, there was some discussion of
> mobility and its IP layer consequences. As various people
> pointed out, cellular networks basically handle this in the
> RAN (Radio Access Network) and therefore at layer 2,
> transparently (well, as much as things ever are) for IP
> purposes. It therefore shouldn't be a problem.
>
> However, as one contributor pointed out, more and more
> cellular operators are migrating traffic onto WLAN for
> various reasons, notably:
>
> 1) Spectrum - it's unlicensed, i.e. free
> 2) Capex - the equipment is cheaper
> 3) Capacity - it's a cheap way of providing high speed
> 4) Signalling load - it gets rid of the signalling traffic
> associated with detaching and attaching devices from the
> core network. This is especially important in view of some
> smartphones' behaviour.
>
> Of course much of the signalling is associated with the
> Mobility Management features, and getting rid of it by
> punting everything to WLAN implies that you lose the
> benefits of this.
>
> That suggests that if you're going to do this on a big
> scale you need to implement Mobile IP or else keep
> backhauling traffic from the WLAN access points to the
> cellular core network (GAN/Iu interface), which has obvious
> effects on the economics of the whole idea.
>
> Alternatively, you can work on the assumption that the WLAN
> is solely for nomadic use rather than true mobility, but a
> lot of devices will prefer the WLAN whenever possible.
>
> Thoughts/experiences?
>
>

The state of the industry is the support of nomadic mobility from cellular
to / from Wi-Fi , there is nearly no support of mobile IP that I have seen.

It is going more and more in this direction. At T-Mobile USA we have
evolved our wifi calling features from fully mobile UMA / GAN to non-mobile
IMS wifi calling.

Cb

>
> --
> The only thing worse than e-mail disclaimers...is people
> who send e-mail to lists complaining about them
 On Dec 30, 2011 9:16 AM, "Alexander Harrowell" <a.harrowell at gmail.com>
wrote:

> In the DHCP v6 thread, there was some discussion of
> mobility and its IP layer consequences. As various people
> pointed out, cellular networks basically handle this in the
> RAN (Radio Access Network) and therefore at layer 2,
> transparently (well, as much as things ever are) for IP
> purposes. It therefore shouldn't be a problem.
>
> However, as one contributor pointed out, more and more
> cellular operators are migrating traffic onto WLAN for
> various reasons, notably:
>
> 1) Spectrum - it's unlicensed, i.e. free
> 2) Capex - the equipment is cheaper
> 3) Capacity - it's a cheap way of providing high speed
> 4) Signalling load - it gets rid of the signalling traffic
> associated with detaching and attaching devices from the
> core network. This is especially important in view of some
> smartphones' behaviour.
>
> Of course much of the signalling is associated with the
> Mobility Management features, and getting rid of it by
> punting everything to WLAN implies that you lose the
> benefits of this.
>
> That suggests that if you're going to do this on a big
> scale you need to implement Mobile IP or else keep
> backhauling traffic from the WLAN access points to the
> cellular core network (GAN/Iu interface), which has obvious
> effects on the economics of the whole idea.
>
> Alternatively, you can work on the assumption that the WLAN
> is solely for nomadic use rather than true mobility, but a
> lot of devices will prefer the WLAN whenever possible.
>
> Thoughts/experiences?
>
>
>
> --
> The only thing worse than e-mail disclaimers...is people
> who send e-mail to lists complaining about them
>


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