100% Agree with you Tom. And these are type of questions we need to answer when we talk about GTP replacement. The control plane in today's mobile core sets up the tunnel and ensure the uniformity of QoS in both forward and backward path.
Can you elaborate on using FAST? FAST on UPFs? Arashmid > -----Original Message----- > From: Tom Herbert [mailto:[email protected]] > Sent: 07 September 2018 11:51 > To: Arashmid Akhavain <[email protected]> > Cc: Dino Farinacci <[email protected]>; [email protected]; > dmm <[email protected]> > Subject: Re: [DMM] Comments to draft-hmm-dmm-5g-uplane-analysis-01 > > On Fri, Sep 7, 2018 at 8:26 AM, Arashmid Akhavain > <[email protected]> wrote: > > Correct, flow labels can change along the path. That's why I like the > > slicing > concept. > > UEs can request services with different attributes, operators control how > service request are mapped into slices. I should look into the air side of the > business and see what happens there. > > Arashmid, > > Yes, slices are a good model. The key question is how does a user's packets > get mapped to the right slice. Presumably, this is done at an ingress point > into the network. There are two ingress points to be considered, one from > UE into the network and one from Internet into network (return path). If the > UE sets bits in the packet to get service in the forward path, we somehow > need to have those bits available on packets in the return path to map > incoming packets. In lieu or requiring the network to maintain a whole bunch > of complex flow state, FAST arranges that the remote server reflects the bits > in response packets. > > Tom > > > > > > > > >> -----Original Message----- > >> From: Tom Herbert [mailto:[email protected]] > >> Sent: 07 September 2018 11:13 > >> To: Arashmid Akhavain <[email protected]> > >> Cc: Dino Farinacci <[email protected]>; > >> [email protected]; dmm <[email protected]> > >> Subject: Re: [DMM] Comments to draft-hmm-dmm-5g-uplane-analysis-01 > >> > >> On Fri, Sep 7, 2018 at 8:01 AM, Arashmid Akhavain > >> <[email protected]> wrote: > >> > > >> > > >> >> -----Original Message----- > >> >> From: Dino Farinacci [mailto:[email protected]] > >> >> Sent: 06 September 2018 18:59 > >> >> To: Arashmid Akhavain <[email protected]> > >> >> Cc: Tom Herbert <[email protected]>; > >> >> [email protected]; dmm <[email protected]> > >> >> Subject: Re: [DMM] Comments to draft-hmm-dmm-5g-uplane-analysis- > 01 > >> >> > >> >> > Dino brought up a good point. Here is my two cents worth: > >> >> > >> >> Not sure which point. > >> >> > >> >> > As it was explained by Sridhar, each UE can have multiple > >> >> > contexts. For > >> >> example, today some operators provide Data and VoLTE service to > >> >> their customers. These two services are represented by separate > >> >> GTP tunnels in the core with each tunnel tied up to a particular QoS. > >> >> > > >> >> > IPv4 didn't fit the bill when GTP work was under way as it > >> >> > couldn't uniquely identify multiple UE > >> >> > >> >> There is no reason why it shouldn’t. And IPv6, for this use-case > >> >> doesn’t add anything new other than a 28 bit > >> >> traffic-class/flow-label that can provide more bits for “new > functionality”. > >> > > >> > > >> > [Arashmid] And that's what I meant. Having a flow label is handy. > >> > We can perhaps use it to identify different UE sessions. > >> > > >> Careful if you use the flow label to identify flows. It should be > >> considered "soft identification" since it might not always be correct > >> (it can be changed en route, isn't protected by any checksum, anyone > >> can set it however they want, etc.). It's useful for things like ECMP > >> that don't require 100% accuracy in identifying flow. The flow label > >> was briefly considered for holding VNIs in network virtualization, but we > talked them out of that. > >> > >> Tom > >> > >> >> > >> >> > sessions/context/bearer. So, GTP and TEID did the job. But I > >> >> > agree with > >> >> Dino that IPv6 is much more versatile and is definitely worth > >> >> looking at as an alternative. > >> >> > >> >> That is not what I said. I said “IP could have solved this problem”. And > “IP” > >> >> means either IPv4 or IPv6, or both at the same time. > >> > > >> > > >> > [Arashmid] > >> > How would we employ IPv4 to distinguish between different UE > sessions. > >> TOS? > >> > Or you mean using encapsulation? > >> > > >> >> > >> >> > A factor worth considering though is that the use of GTP and > >> >> > TEID in mobile > >> >> core allows operators to deal with QoS on their own terms. The > >> >> tunnels with specific operator-controlled QoS are established by > >> >> the control plane between eNB, SGW, and PGW. UEs or applications > >> >> sitting in the UEs have no say in this. Well at least till the > >> >> packet exits operator's > >> network. > >> >> > >> >> The problem with one header, is that if you re-mark (known as PHB > >> >> markign in the ole days) you lose the original value. > >> >> Encapsulation is useful here because you can map the inner to > >> >> outer and anywhere along the path you can PHB remark on the outer > >> >> header. And then the destination can see the orignal source’s > ToS/QoS/TC/flow-label whatever. > >> > > >> > > >> > [Arashmid] Yes, I agree. The original value is lost with PHB. > >> > Encapsulation certainly makes things easier and the inner to outer > >> > mapping trick has been widely used in IP and MPLS(multiple labels > >> > like service and transport) > >> > > >> >> > >> >> > Using the information in UE's IP packet header can jeopardise > >> >> > the above tight QoS control. I think going > >> >> > >> >> Not if you encapsulate. But note with SRv6, you can possibly > >> >> retain the original flow-label if the SID can retain those bits > >> >> before overwriting the destination address from the option’s value. > >> > > >> > [Arashmid] Agree. Encapsulation does the trick again. That's why > >> > GTP has worked well and served the purpos in the mobile back-haul so > far. > >> > > >> >> > >> >> Dino > >> >> > >> >> > down this path, operators need proof that they will be still in > >> >> > the driving > >> >> seat and QoS cannot be dictated/tampered by the UE or any > >> >> application running in it. > >> >> > > >> >> > Now, here is an interesting question for the operators. Would > >> >> > any operator > >> >> be interested in allowing QoS to be set by the UE or by > >> >> applications running in the UE and charged for by the network? > >> >> "Yes" could potentially imply impacts on the air interface, UE > >> >> resource block allocation and can make scheduling on the RAN side > much more complex. > >> >> > > >> >> > Arashmid > >> >> > > >> >> > > >> >> >> -----Original Message----- > >> >> >> From: dmm [mailto:[email protected]] On Behalf Of Dino > >> >> >> Farinacci > >> >> >> Sent: 06 September 2018 12:45 > >> >> >> To: Tom Herbert <[email protected]> > >> >> >> Cc: [email protected]; dmm <[email protected]> > >> >> >> Subject: Re: [DMM] Comments to > >> >> >> draft-hmm-dmm-5g-uplane-analysis- > >> 01 > >> >> >> > >> >> >>> Behcet, > >> >> >>> > >> >> >>> I was thinking if TEID is need then that can be encoded in a > >> >> >>> locator easily enough. > >> >> >>> > >> >> >>> Tom > >> >> >> > >> >> >> Not if a locator is a PGW that is shared by many UEs. > >> >> >> > >> >> >> 3GPP wants per bearer awareness so they need a specific ID, > >> >> >> that could have been the UE’s IP address. And with IPv6 it can > >> >> >> be unique and not the issue that Sridhar brought up. > >> >> >> > >> >> >> If ILA was in use, just use the ILA-ID for this purpose. > >> >> >> > >> >> >> Dino > >> >> >> > >> >> >> _______________________________________________ > >> >> >> dmm mailing list > >> >> >> [email protected] > >> >> >> https://www.ietf.org/mailman/listinfo/dmm > >> > _______________________________________________ dmm mailing list [email protected] https://www.ietf.org/mailman/listinfo/dmm
