> I understand your point, but there is no guarantee for a precise QoS without > using some sort of encapsulation being it GTP, RSVP, etc. Even with tunnels, > there is no guarantee that all nodes along the path have the same hardware > capability and can provide the same QoS treatment.
There is existing hardware where the encapsulator copies inner QoS to outer QoS. All routers along the path just process the outer QoS, no changes to or new processing requirements for them. > For example, the code points in routers need to be configured to correctly > handle the EXP bits in MPLS labels. But there is no guarantee that all > routers can support all values. The EXP values get mapped to code points but > the mapping is not always one to one. 3-bit EXPs can map to 4 code points on > those routers with less capable H/W. That is a completely different matter. The discussion is about remarking. And if one remarks to what the path cannot support, well things don’t work as expected. > Slicing is almost the same. It allows user traffic to be mapped to what the > operator provides. > I agree with you that network should not touch/change original header bits. > GTP or any other encapsulation easily allow for this. The question is whether > we can provide for this without using encapsulation. IPv6 might be the > answer. But as Tom pointed out, flow labels can still change in the middle. > Is there any room for improvement. SIDs might present an opportunity. Not if they are encapsulated and routers don’t touch packets inside. Dino > > > > > >> -----Original Message----- >> From: Dino Farinacci [mailto:farina...@gmail.com] >> Sent: 07 September 2018 13:08 >> To: Arashmid Akhavain <arashmid.akhav...@huawei.com> >> Cc: Tom Herbert <t...@quantonium.net>; ta-miyas...@kddi-research.jp; >> dmm <dmm@ietf.org> >> Subject: Re: [DMM] Comments to draft-hmm-dmm-5g-uplane-analysis-01 >> >> I think you’ll still have the PHB re-marking issues I mentioned in previous >> emails. The question is, should the network touch/change any header bits of >> the packet the source has built. The answer should probably be no. >> >> Having said that, GTP did it the right way, even though it cost in header >> length. >> >> Dino >> >>> On Sep 7, 2018, at 8:26 AM, Arashmid Akhavain >> <arashmid.akhav...@huawei.com> 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. >>> >>> >>> >>>> -----Original Message----- >>>> From: Tom Herbert [mailto:t...@quantonium.net] >>>> Sent: 07 September 2018 11:13 >>>> To: Arashmid Akhavain <arashmid.akhav...@huawei.com> >>>> Cc: Dino Farinacci <farina...@gmail.com>; >>>> ta-miyas...@kddi-research.jp; dmm <dmm@ietf.org> >>>> Subject: Re: [DMM] Comments to draft-hmm-dmm-5g-uplane-analysis-01 >>>> >>>> On Fri, Sep 7, 2018 at 8:01 AM, Arashmid Akhavain >>>> <arashmid.akhav...@huawei.com> wrote: >>>>> >>>>> >>>>>> -----Original Message----- >>>>>> From: Dino Farinacci [mailto:farina...@gmail.com] >>>>>> Sent: 06 September 2018 18:59 >>>>>> To: Arashmid Akhavain <arashmid.akhav...@huawei.com> >>>>>> Cc: Tom Herbert <t...@quantonium.net>; ta-miyasaka@kddi- >> research.jp; >>>>>> dmm <dmm@ietf.org> >>>>>> 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:dmm-boun...@ietf.org] On Behalf Of Dino >>>>>>>> Farinacci >>>>>>>> Sent: 06 September 2018 12:45 >>>>>>>> To: Tom Herbert <t...@quantonium.net> >>>>>>>> Cc: ta-miyas...@kddi-research.jp; dmm <dmm@ietf.org> >>>>>>>> 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 >>>>>>>> dmm@ietf.org >>>>>>>> https://www.ietf.org/mailman/listinfo/dmm >>>>> > _______________________________________________ dmm mailing list dmm@ietf.org https://www.ietf.org/mailman/listinfo/dmm
