Re: [5gangip] New Version Notification for draft-xyzy-atick-gaps-00.txt

["FIGURELLE, TERRY F" <[e-mail]>]

Vendors do proprietary stuff on X2 so you can't do an X2 handoff between Nokia and Ericsson eNB's. You also can't use X2 between an IPv6 addressed eNB and an IPv4 addressed eNB. When you can't use X2 you are stuck with S1. Typically there is more latency to SGW and thus timing is tight.

The address family is only an issue if you migrate from IPv4 to IPv6 for transport and really it wasn't that big of a deal. Inter-vendor is a different story since there is always an edge somewhere when you use two or more vendors. We only need to keep the amount of S1 handoffs within bounds and know what issues can occur.

If you look at the 3GPP Inter-MME Inter-SGW S1 handoff with indirect forwarding call flow you will know what I mean. That’s a lot of stuff to happen in a short amount of time. Since its common for RAN-MME-SGW to be from same vendor on some networks (not ours) this means where that edge happens you better cross your fingers!

If there isn't active traffic flow or you can suspend  then resume: S1 isn't a problem. But when you get some of those IMS call flows where you have 5 dedicated bearers and some are GBR, things get a bit wild. As an FYI the UE chipsets only support 5-3 ack/un-ack or un-ack/ack (I forget which off top of my head) so you have to be careful how many bearers of what flavor you have.

So far the IMS services people have not shown any restraint on using up resources.

> -----Original Message-----
> From: Dino Farinacci <[e-mail]>
> Sent: Thursday, June 07, 2018 3:18 PM
> To: FIGURELLE, TERRY F <[e-mail]>
> Cc: Tom Herbert <[e-mail]>; Luigi Iannone <[e-mail]>;
> 5GANGIP <[e-mail]>
> Subject: Re: [5gangip] New Version Notification for draft-xyzy-atick-gaps-
> 00.txt
> 
> On Jun 7, 2018, at 2:12 PM, FIGURELLE, TERRY F <[e-mail]> wrote:
> >
> > The MTU mismatch?
> 
> Yes, thanks for the explaination. But what are the other two issues:
> “between vendors” and “between address families”.
> 
> Dino
> 
> >
> > We already have vendors working on auto-MTU adjust and working on
> device requirements so whenever it gets an updated MTU in PCO the device
> will honor it. We were told that this is something 3GPP would not be
> interested in since it is a temp deployment challenge not a long term
> challenge. Plus we require MRU>MTU so most elements can get a larger
> packet then they can send. We can set MTU per APN so the 5G APN is set to
> use full 1500 byte "Internet" MTU.
> >
> > Thus you can have a network where legacy APN's stull do their thing then
> decide when/where to use larger MTU. IMS looks ripe for a larger than 1500
> byte MTU. Those SIP messages can be huge. But we need to validate all the
> vendors can support this and work the details to get there.
> >
> > Now if you can get the entire Internet to support more that 1500 byte
> MTU, you are better than me.
> >
> > We worked a lot on MTU discovery but even for IPv6 this just doesn't
> > pan out. I wish it did but realities sometimes suck and its taking way
> > too long to get to all IPv6 ☹
> >
> > Now if you meant something else please rephrase it concisely.
> >
> >> -----Original Message-----
> >> From: Dino Farinacci <[e-mail]>
> >> Sent: Thursday, June 07, 2018 1:34 PM
> >> To: FIGURELLE, TERRY F <[e-mail]>
> >> Cc: Tom Herbert <[e-mail]>; Luigi Iannone
> <[e-mail]>;
> >> 5GANGIP <[e-mail]>
> >> Subject: Re: [5gangip] New Version Notification for
> >> draft-xyzy-atick-gaps- 00.txt
> >>
> >>> Apparently X2 handoffs not only can’t go between vendor and IP
> >>> address
> >> families they can’t go between MTU sizes. So we need to do all the
> >> tracking areas in a market to avoid S1 handovers.
> >>
> >> Do you think this is a problem worth solving?
> >>
> >> Dino