Hello Tom,

Thank you for your feedback.

> ...snip...

> - Pick a handful of representative formats, maybe something like five,
> and do an an equivalent comparison. For instance, it should be easy to
> deduce the equivalent packet formats for traditional mode in SR that
> are needed for GTP and ILA.

I want to do. But I’d keep them until it is clear those are truly not deployed 
in rest of world.
When it’s clear I remove them.


> - Don't count the outer Ethernet header as overhead. It's always there
> and not counted against MTU.

When it comes to overhead, it affects not only for MTU size, but also consumed 
bandwidth.
In that perspective, I’d keep Ethernet header in it. Or, do you want to resume 
the discussion of ‘killing ethernet’ thread in ietf at ietf list?


> - Don't use colors to highlight differences. The use of 'red' in the
> spreadsheet is subjective and also confusing in itself. For instance,
> I don't understand why 'No SRH' (line 1) is black but basic GTP over
> IPv4 (line 5) is red when they are both reported to have 58 bytes of
> overhead.

This is comparison of overhead size against SRv6 Mobile User Plane so that SRv6 
is base and no need to be colored.
I can change red to other color.


> - Is the math is off? For instance, in line 1 the overhead is an IPv6
> header and and Ethernet header, shouldn't that be 40+14=54 instead of
> 58?

FCS counted.

Cheers,
--satoru


> 
> Tom
> 
> 
> 
> 
> 
>> 
>>> 
>>> 3. How to encode QFI, RQI in SRv6 (both traditional mode and enhanced 
>>> mode)? In GTPU the QFI/RQI markings are carried in a GTPU extension header, 
>>> defined as a container. Please refer the following documents for details
>> 
>> Thank you for those latest references! Actually I was seeking them from last 
>> CT4 meeting folder. ;-)
>> 
>> And yes, we still leave it at this time since defining 3GPP specific 
>> extension headers and messages should be up to 3GPP decision.
>> We don’t want to violate that responsibility. Nevertheless, in case that 
>> those GTP-U extension header and messages are carried as its encoding, TLV 
>> in SRH would work to do that with just one or few code points to 3GPP which 
>> looks not big deal. If you are interested, it would be nice if we can write 
>> a draft with that idea with you and John.
>> 
>> Cheers,
>> --satoru
>> 
>>> 
>>> Incoming LS from RAN3 to CT4: 
>>> http://www.3gpp.org/ftp/tsg_ct/WG4_protocollars_ex-CN4/TSGCT4_83_Montreal/Docs/C4-182214.zip
>>> 
>>> Corresponding agreed CR in CT4: 
>>> http://www.3gpp.org/ftp/tsg_ct/WG4_protocollars_ex-CN4/TSGCT4_83_Montreal/Docs/C4-182246.zip
>>> 
>>> LS out from CT4 to RAN3: 
>>> http://www.3gpp.org/ftp/tsg_ct/WG4_protocollars_ex-CN4/TSGCT4_83_Montreal/Docs/C4-182247.zip
>>> 
>>> Thanks
>>> Sridhar
>>> 
>>> -----Original Message-----
>>> From: dmm [mailto:dmm-boun...@ietf.org] On Behalf Of Satoru Matsushima
>>> Sent: Tuesday, March 13, 2018 6:55 AM
>>> To: John Kaippallimalil <john.kaippallima...@huawei.com>
>>> Cc: dmm <dmm@ietf.org>
>>> Subject: Re: [DMM] Fwd: I-D Action: draft-ietf-dmm-srv6-mobile-uplane-01.txt
>>> 
>>> John,
>>> 
>>>> 2018/03/13 7:37、John Kaippallimalil <john.kaippallima...@huawei.com>のメール:
>>>> 
>>>> A few questions for clarification:
>>>> 1. Section 5.1.1, "..Since there is only one SID, there is no need to push 
>>>> an SRH..."
>>>> In this case the outer IPv6 address representing a SID would contain a 
>>>> TEID.
>>>> So for 1000 PDU sessions - would there be as many IPv6 addresses
>>>> (representing SIDs/TEID in the outer header)
>>> 
>>> Right. It is not limited but in a typical case given that a /64 per node 
>>> for the SID space which allows each node allocate a SID per session basis.
>>> 
>>> 
>>>> 
>>>> 2.  Section 5.2 (& Figure 3), suppose there were more than 1 UPF on
>>>> path (gNB --> UPF1 --> UPF2 as in the example in 5.1 but now with other 
>>>> fns - S1, C1) Would the SR path at gNB (uplink) be (a) the list of SIDs to 
>>>> chain functions along the path to UPF1,
>>>>     or, would it be (b) the list of SIDs to chain functions, plus UPF1, .. 
>>>> upto the anchor UPF2.
>>> 
>>> Please see the section 5.2.1 of packet flow on uplink.
>>> We assume that there’s no UPF1 along the path in the diagram.
>>> 
>>> 
>>>> 
>>>> 3.  Section 5.2, "The SR policy MAY include SIDs for traffic engineering 
>>>> and service chaining ..."
>>>> 3GPP service chaining is at N6 interface, but in this case, is the policy 
>>>> for traffic steering implemented at the N3  interface.
>>>> Would PCF/SMF provision this at gNB.
>>> 
>>> When it comes to enhanced mode for control-plane side, it may literally be 
>>> enhanced.
>>> But at this revision of the draft, it is assumed that gNB is capable to 
>>> resolve SR policy from remote endpoint address of tunnel to SIDs list while 
>>> N2 is unchanged and kept as it is.
>>> 
>>> Cheers,
>>> --satoru
>>> 
>>> 
>>>> 
>>>> Thanks,
>>>> John
>>>> 
>>>> 
>>>> 
>>>> -----Original Message-----
>>>> From: Satoru Matsushima [mailto:satoru.matsush...@gmail.com]
>>>> Sent: Mittwoch, 7. März 2018 12:23
>>>> To: Marco Liebsch
>>>> Cc: dmm
>>>> Subject: Re: [DMM] Fwd: I-D Action:
>>>> draft-ietf-dmm-srv6-mobile-uplane-01.txt
>>>> 
>>>> Marco,
>>>> 
>>>>> 2018/03/07 18:41、Marco Liebsch <marco.lieb...@neclab.eu>のメール:
>>>>> 
>>>>> Satoru,
>>>>> 
>>>>> since I read this at different places, let me ask one clarifying question 
>>>>> about the stateless motivation:
>>>>> 
>>>>> I see that for SRv6 you may not need a state at the egress (at least
>>>>> not for traffic forwarding) but for Uplink/Downlink (UL/DL) you need
>>>>> a state at both edges of the communication since the DL egress serves as 
>>>>> uplink ingress, correct?
>>>> 
>>>> 2x unidirectional tunnels to form bidirectional paths require 4 states in 
>>>> total at both the ingress and egress.
>>>> In SR case it requires just 2 states at the ingresses for both directions.
>>>> 
>>>> Cheers,
>>>> --satoru
>>>> 
>>>> 
>>>> 
>>>>> 
>>>>> marco
>>>>> 
>>>>> 
>>>>> -----Original Message-----
>>>>> From: dmm [mailto:dmm-boun...@ietf.org] On Behalf Of Satoru
>>>>> Matsushima
>>>>> Sent: Dienstag, 6. März 2018 17:23
>>>>> To: Tom Herbert
>>>>> Cc: dmm
>>>>> Subject: Re: [DMM] Fwd: I-D Action:
>>>>> draft-ietf-dmm-srv6-mobile-uplane-01.txt
>>>>> 
>>>>> Hello Tom,
>>>>> 
>>>>>>> A Big progress is that the draft supports interworking with GTP
>>>>>>> over
>>>>>>> IPv6 in addition to GTP over IPv4.
>>>>>>> And we have made change SRv6 function to IPv6 encapsulation with
>>>>>>> SRH instead of SRH insertion by default.
>>>>>>> 
>>>>>> 
>>>>>> Hi Satoru,
>>>>>> 
>>>>>> If there are no intermediate hops od SIDs being set when
>>>>>> encapsulating would a SR header still be needed or could this just
>>>>>> be simple IP in IP encpasulation?  If is no SR header then it's
>>>>>> possible that ILA might then be used to completely eliminate the 
>>>>>> encapsulation overhead.
>>>>> 
>>>>> I think you’re right. You would find that case in the draft as 
>>>>> ‘Traditional Mode’ which is equivalent with traditional GTP-U case. You 
>>>>> seem you say ILA is also equivalent with that mode. In addition, this 
>>>>> draft introduces ‘Enhance Mode’ to cover more advanced cases.
>>>>> 
>>>>> IMO SR is designed not to maintain path states except at an ingress node. 
>>>>> So the packet need to preserve original DA in the header that keep the 
>>>>> egress node in stateless. It would be great if ILA is designed in the 
>>>>> similar concept as well.
>>>>> 
>>>>> If it’s not, it looks a kind of tradeoff, between reducing the overhead 
>>>>> and keeping the statelessness. It’s not apple-to-apple comparison. To 
>>>>> decide to choose which one need to be prioritized would depend on each 
>>>>> deployment case in operators IMO.
>>>>> 
>>>>> Cheers,
>>>>> --satoru
>>>>> _______________________________________________
>>>>> dmm mailing list
>>>>> dmm@ietf.org
>>>>> https://www.ietf.org/mailman/listinfo/dmm
>>>> 
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