Re: Questions about SRv6 mobile user-plane

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Hi Tom,

Thank you, first of all, for your interest!

Yes, SID list can be reduced in some cases. I agree it should be restricted
to the minimum necessary.

I think ILA and SRv6 share a common view, while SRv6 allows more flexible
functions.

Regarding RFC8200, attacks can be and should be prevented in another way.
If under agreement, header insertion, which could make network more
efficient, should be allowed.

I hope ILA and SRv6 converge.

Miya@a co-author of SRv6 mobile data plane

On Sat, Jan 27, 2018 at 2:13 AM, Tom Herbert <[email protected]> wrote:

> Hello,
>
> I am working on a comparison between ILA and SRv6 for the mobile
> user-plane. I have some questions/comments about SRv6 and particularly on
> the example use cases that were depicted in the slides that were presented
> in IETF100:
>
> https://datatracker.ietf.org/meeting/100/materials/slides-
> 100-dmm-srv6-for-mobile-user-plane/
>
> - It's clear from the depicted use cases that extension header insertion
> is being done by intermediate nodes, but extension header insertion is
> currently prohibited by RFC8200. There was an I-D posted on 6man to allow
> this for SR, but that was met with pushback. Is there going to be followup
> to resolve this?
>
> - For the uplink use cases, this seems to be more like using SR to source
> route to an egress router. In other words, it's not strictly related to
> mobility. Is there some connection to mobility that I'm missing?
>
> - The size or number of SR headers in the uplink cases seems to be larger
> than necessary (IMO minimizing these is important since each additional sid
> is ~1% overhead of standard MTU). In this first scenario sid[1]=A2::1 and
> DA=A2::1-- this seems to be redundant information. Also this depicts a
> second SR being inserted, but the first one should no longer be relevant.
> Why not just discard the first one and save the overhead? In the second
> scenario, DA is changing from A2::1 to A3::1, but AFAICT that was not done
> per the SR processing. What is the operation that happened here? (it's
> actaully looks like an ILA transfomation).
>
> - Considering the points above, could this have been done in the following
> manner to minimize overhead? A1 creates one SRH with one sid and makes
> DA=A2. A2 makes DA=A3. At A3 SR is processed, DA is restored to Internet
> address, and EH is removed.
>
> - For downlink this does see to be relevant to mobility. But I have the
> same question, wouldn't it be less overhead to only use one SRH and one
> sid? i.e. A3 creates an SRH with just one sid that is the S:: (identifier
> in identifier/locator speak) and set DA to A2, and then A2 sets DA to A1,
> A1 restores original packet for delivery.
>
> - One possible typo. In the last use case slide SA=S:: and DA=D::, I
> believe these should be swapped?
>
> Thanks,
> Tom
>
>
>
>
>
> _______________________________________________
> dmm mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/dmm
>
>

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<div dir=3D"ltr">Hi Tom,<div><br></div><div>Thank you, first of all, for yo=
ur interest!=C2=A0</div><div><br></div><div>Yes, SID list can be reduced in=
 some cases. I agree it should be restricted to the minimum necessary.=C2=
=A0</div><div><br></div><div>I think ILA and SRv6 share a common view, whil=
e SRv6 allows more flexible functions.<br></div><div><br></div><div>Regardi=
ng RFC8200, attacks can be and should be prevented in another way. If under=
 agreement, header insertion, which could make network more efficient, shou=
ld be allowed.=C2=A0</div><div><br></div><div>I hope ILA and SRv6 converge.=
=C2=A0</div><div><br></div><div>Miya@a co-author of SRv6 mobile data plane<=
/div></div><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">On Sat=
, Jan 27, 2018 at 2:13 AM, Tom Herbert <span dir=3D"ltr">&lt;<a href=3D"mai=
lto:[email protected]" target=3D"_blank">[email protected]</a>&gt;</span>=
 wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bor=
der-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr"><div>Hello,</div=
><div><br></div><div>I am working on a comparison between ILA and SRv6 for =
the mobile user-plane. I have some questions/comments about SRv6 and partic=
ularly on the example use cases that were depicted in the slides that were =
presented in IETF100:</div><div><br></div><a href=3D"https://datatracker.ie=
tf.org/meeting/100/materials/slides-100-dmm-srv6-for-mobile-user-plane/" ta=
rget=3D"_blank">https://datatracker.ietf.org/<wbr>meeting/100/materials/sli=
des-<wbr>100-dmm-srv6-for-mobile-user-<wbr>plane/</a><br><div><br></div><di=
v>- It&#39;s clear from the depicted use cases that extension header insert=
ion is being done by intermediate nodes, but extension header insertion is =
currently prohibited by RFC8200. There was an I-D posted on 6man to allow t=
his for SR, but that was met with pushback. Is there going to be followup t=
o resolve this?</div><div><br></div><div>- For the uplink use cases, this s=
eems to be more like using SR to source route to an egress router. In other=
 words, it&#39;s not strictly related to mobility. Is there some connection=
 to mobility that I&#39;m missing?</div><div><br></div><div>- The size or n=
umber of SR headers in the uplink cases seems to be larger than necessary (=
IMO minimizing these is important since each additional sid is ~1% overhead=
 of standard MTU). In this first scenario sid[1]=3DA2::1 and DA=3DA2::1-- t=
his seems to be redundant information. Also this depicts a second SR being =
inserted, but the first one should no longer be relevant. Why not just disc=
ard the first one and save the overhead? In the second scenario, DA is chan=
ging from A2::1 to A3::1, but AFAICT that was not done per the SR processin=
g. What is the operation that happened here? (it&#39;s actaully looks like =
an ILA transfomation).</div><div><br></div><div>- Considering the points ab=
ove, could this have been done in the following manner to minimize overhead=
? A1 creates one SRH with one sid and makes DA=3DA2. A2 makes DA=3DA3. At A=
3 SR is processed, DA is restored to Internet address, and EH is removed.</=
div><div><br></div><div>- For downlink this does see to be relevant to mobi=
lity. But I have the same question, wouldn&#39;t it be less overhead to onl=
y use one SRH and one sid? i.e. A3 creates an SRH with just one sid that is=
 the S:: (identifier in identifier/locator speak) and set DA to A2, and the=
n A2 sets DA to A1, A1 restores original packet for delivery.</div><div><br=
></div><div>- One possible typo. In the last use case slide SA=3DS:: and DA=
=3DD::, I believe these should be swapped?</div><div><br></div><div>Thanks,=
</div><div>Tom</div><div><br></div><div>=C2=A0</div><div><br></div><div><br=
></div></div>
<br>______________________________<wbr>_________________<br>
dmm mailing list<br>
<a href=3D"mailto:[email protected]">[email protected]</a><br>
<a href=3D"https://www.ietf.org/mailman/listinfo/dmm" rel=3D"noreferrer" ta=
rget=3D"_blank">https://www.ietf.org/mailman/<wbr>listinfo/dmm</a><br>
<br></blockquote></div><br></div>

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