Re: [spring] End.DT/End.DX SIDs (was Re: USD/USP question in draft-ietf-spring-srv6-network-programming-06.txt)

Gyan Mishra <hayabusagsm@gmail.com> Thu, 19 December 2019 22:51 UTC

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From: Gyan Mishra <hayabusagsm@gmail.com>
Date: Thu, 19 Dec 2019 17:51:08 -0500
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To: Ron Bonica <rbonica@juniper.net>
Cc: "Pablo Camarillo (pcamaril)" <pcamaril@cisco.com>, "Voyer, Daniel" <daniel.voyer@bell.ca>, "Wang, Weibin (NSB - CN/Shanghai)" <weibin.wang@nokia-sbell.com>, "spring@ietf.org" <spring@ietf.org>
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Subject: Re: [spring] End.DT/End.DX SIDs (was Re: USD/USP question in draft-ietf-spring-srv6-network-programming-06.txt)
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On Thu, Dec 19, 2019 at 11:28 AM Ron Bonica <rbonica@juniper.net>; wrote:

> Pablo,
>
>
>
> In L3VPN, all of these are combined into a single 20-bit MPLS label. Why
> can SRv6 not do likewise?
>
>
>
>                                              Ron
>
>  [Gyan] Very good point.  All of those are related to BOS=1 vpn service
> label.  This is covered with BESS in detail in the L3 vpn service SID.
>
https://tools.ietf.org/pdf/draft-ietf-bess-srv6-services-01.pdf
> SRv6 programming is related to the end.x cross connects within the SR
> domain similar to in MPLS terms “topmost label”.  So the external to SRv6
> domain,  PE-CE M-BGP BGP services is really separate covered by the draft
> above.
>



>
> Juniper Business Use Only
>
> *From:* spring <spring-bounces@ietf.org>; *On Behalf Of *Pablo Camarillo
> (pcamaril)
> *Sent:* Thursday, December 19, 2019 6:47 AM
> *To:* Wang, Weibin (NSB - CN/Shanghai) <weibin.wang@nokia-sbell.com>;;
> Gyan Mishra <hayabusagsm@gmail.com>;
> *Cc:* spring@ietf.org; Voyer, Daniel <daniel.voyer@bell.ca>;
> *Subject:* [spring] End.DT/End.DX SIDs (was Re: USD/USP question in
> draft-ietf-spring-srv6-network-programming-06.txt)
>
>
>
> Gyan,
>
>
>
> The End.DX4/End.DX6 can be seen as an equivalent to the MPLS per-CE VPN
> label.
>
> The End.DT4/End.DT6 can be seen as an equivalent to the MPLS per-VRF VPN
> label.
>
>
>
> I believe that they cannot be combined.
>
>
>
> Cheers,
>
> Pablo.
>
>
>
> *From: *Gyan Mishra <hayabusagsm@gmail.com>;
> *Date: *Sunday, 15 December 2019 at 08:29
> *To: *"Wang, Weibin (NSB - CN/Shanghai)" <weibin.wang@nokia-sbell.com>;
> *Cc: *"Pablo Camarillo (pcamaril)" <pcamaril@cisco.com>;, "Voyer, Daniel" <
> daniel.voyer@bell.ca>;, "spring@ietf.org"; <spring@ietf.org>;
> *Subject: *Re: [spring] USD/USP question in
> draft-ietf-spring-srv6-network-programming-06.txt
>
>
>
>
>
> Hi Wang & Pablo & Spring Authors,
>
>
>
> Had another question?
>
>
>
> These 4 sections.  Trying to understand the difference between end.dx4
> end.dx6 and end.dt4 and end.dt6.  They both seem very similar.  One says
> xconnect but other has v4 v6 lookup but for both you have to signal  L3 vpn
> services sid.  Not sure why both SIDs dx dt Sid function why they cannot be
> combined.
>
>
>
> I noticed this difference below that the dx4 dt4 account for the global
> table scenario where the PE-CE is native IPv4 or IPv6.  In the MPLS world
> that use case is very different in that there is not any L3 vpn label and
> do the label stack only had a single topmost label.  Also in the MPLS
> scenario with IPv6 global table PE-CE with a IPv4 core you require BGP -LU
> labeled unicast “send label” to label all the IPv6 prefixed tunneled over
> IPv4.   Since that scenario is very different with global table does it
> make sense to have a separate End.x variant for global table for both IPv4
> and IPv6.
>
>
>
>    Note that an End.DT6 may be defined for the main IPv6 table in which
>
>    case and End.DT6 supports the equivalent of an IPv6inIPv6
>
>    decapsulation (without VPN/tenant implication).
>
>
>
>      4.4 <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*section-4.4__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JAaJnI7_$>;.  End.DX6: Decapsulation and IPv6 cross-connect . . . . . .  12 <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*page-12__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JH8Abwf7$>
>
>      4.5 <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*section-4.5__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JEh8sRB2$>;.  End.DX4: Decapsulation and IPv4 cross-connect . . . . . .  13 <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*page-13__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JHAg09NC$>
>
>      4.6 <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*section-4.6__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JHVgWtPg$>;.  End.DT6: Decapsulation and specific IPv6 table lookup . .  14 <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*page-14__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JA89XfKV$>
>
>      4.7 <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*section-4.7__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JF59SaCO$>;.  End.DT4: Decapsulation and specific IPv4 table lookup . .  15 <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*page-15__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JICjeckL$>
>
>
>
> Also I was trying to understand end.dt46.
>
>
>
> So if the PE-CE edge is dual stacked anhas both v4 and v6 you have a VRF tenant v4 and v6 separate peers signaled via L3 vpn services TLV.  So why do you need this end.dt46 sid
>
>
>
> 4.8 <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*section-4.8__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JMbbI6-v$>;.  End.DT46: Decapsulation and specific IP table lookup  . .  16 <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*page-16__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JMihsn8k$>
>
>
>
>
>
> Kind Regards,
>
>
>
> Gyan
>
>
>
> On Sun, Dec 15, 2019 at 2:06 AM Gyan Mishra <hayabusagsm@gmail.com>; wrote:
>
> Hi Wang
>
>
>
> I have a question regarding the PSP, USP and USD sections I pasted below.
>
>
>
> I just sent an email to Spring WG related to PSP and technically why that
> is necessary as that is a legacy concept that has parity to MPLS but is not
> used today due to QOS issues.  Please see that email related to that topic.
>
>
>
>
>
> In the PSP section can If we have to keep PSP can we add verbiage that
> states that PSP removal of the SRH header occurs on the Penultimate egress
> P node.
>
>
>
> In the USP section can we also add that all remaining SRH present in the
> packet are popped on the egress PE ultimate node.
>
>
>
> In looking at these 3 SID functions the PSP and USP pop the EH and the USP
> removes the 6in6 encapsulation so that the other end.x dt4 dt6 etc can pop
> the services L3vpn headers.
>
>
>
> Why can’t the USD 6in6 encapsulation removal be done on with the USP SID?
>
>
>
> Why does the USP and USD SID have to be separate?
>
>
> 4.16.1
> <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*section-4.16.1__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JNXuPqZh$>;.
> PSP: Penultimate Segment Pop of the SRH
>
>
>
>
>
>    The SRH processing of the End, End.X and End.T behaviors are
>
>    modified: after the instruction "S14.  Update IPv6 DA with Segment
>
>    List[Segments Left]" is executed, the following instructions must be
>
>    executed as well:
>
>
>
>    S14.1.   If (updated SL == 0) {
>
>    S14.2.      Pop the SRH
>
>    S14.3.   }
>
>
>
> 4.16.2
> <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*section-4.16.2__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JLGcpaqu$>;.
> USP: Ultimate Segment Pop of the SRH
>
>
>
>
>
>    The SRH processing of the End, End.X and End.T behaviors are
>
>    modified: the instructions S02-S04 are substituted by the following
>
>    ones:
>
>
>
>    S02.   If (Segments Left == 0) {
>
>    S03.       Pop the SRH
>
>    S04.   }
>
>
>
> 4.16.3
> <https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-05*section-4.16.3__;Iw!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JKFZ-dKZ$>;.
> USD: Ultimate Segment Decapsulation
>
>
>
>
>
>    The SRH processing of the End, End.X and End.T behaviors are
>
>    modified: the instructions S02-S04 are substituted by the following
>
>    ones:
>
>
>
>    S02.   If (Segments Left == 0) {
>
>    S03.      Skip the SRH processing and proceed to the next header
>
>    S04.   }
>
>
>
>
>
>    Further on, the Upper-layer header processing of the End, End.X and
>
>    End.T behaviors are modified as follows:
>
>
>
>
>
> Kind regards,
>
>
>
> Gyan
>
>
>
> On Sat, Dec 14, 2019 at 9:08 PM Wang, Weibin (NSB - CN/Shanghai) <
> weibin.wang@nokia-sbell.com>; wrote:
>
> Hi Pablo:
>
>
>
> After the 2 context assumption in previous version of this draft,  “we
> assume that there is no other extension header than the SRH.”  and  “We
> assume
>
>    that the SRH may be present multiple times inside each packet”, are
> removed in this last draft, I feel a bit confusion on USD SID, as well as
> combination of USD & USP.
>
>
>
> First, within the content of this last draft, the word “Further on” marked
> red in the following pseudocode in section “4.16.3” is hard to understand
> if the packet being processed has other EH embed between SRH and
> Upper-layer header, such as AH or other EH, then the processing control of
> this packet will be passed to normal IPv6 module from current SRH
> processing module in SR-Node, so my question is : Can its control after
> completing AH processing (for example)  be back to SRH module (or call it
> pseudocode module) to proceed the next header like “upper-lay header type
> ==41 or 4”.
>
> Or, if not, Did you created a new EH processing protocol stack instance in
> parallel to normal IPv6 module within the scope of SRH processing in
> SR-node.
>
>
>
> 4.16.3.  USD: Ultimate Segment Decapsulation
>
>
>
> S02.   If (Segments Left == 0) {
>
>    S03.      Skip the SRH processing and proceed to the next header
>
>    S04.   }
>
>
>
> Further on, the Upper-layer header processing of the End, End.X and
>
>    End.T behaviors are modified as follows:
>
>
>
>    End:
>
>    S01. If (Upper-layer Header type == 41 || 4) {
>
>    S02.    Remove the outer IPv6 Header with all its extension headers
>
>    S03.    Submit the packet to the egress IP FIB lookup and
>
>               transmission to the new destination
>
>    S04. } Else {
>
>    S05.    Send an ICMP Parameter Problem message to the Source Address
>
>               Code 4 (SR Upper-layer Header Error),
>
>               Pointer set to the offset of the upper-layer header.
>
>               Interrupt packet processing and discard the packet.
>
>
>
>    S06. }
>
>
>
> From my understanding, the all processing action about specific SID must
> be completed successively. That is to say, upon USD, the upper-layer header
> (type 41 or 4) must be followed the SRH header being processed currently,
> or second SRH following the same rule (of course, the draft not considering
> 2 or more successive SRHs).
>
>
>
> Second, the mixed SIDs function with combination of USD and USP (even
> PSP&USD&USP), I think, it is easy to understand when the two assumption
> above exist, but now I think it isn’t clear if you only provide the
> following sentence in this draft, i.e.  “if … else…” statement:
>
> “An implementation that supports the USD flavor in conjunction with
>
>    the USP flavor MAY optimize the packet processing by first looking
>
>    whether the conditions for the USD flavor are met, in which case it
>
>    can proceed with USD processing else do USP processing.”
>
> This confusion is also described in my another mail. Of course, if the
> first question is addressed then this confusion does not exist.
>
>
>
> By the way, is it really no different in text description before and after
> the two context assumption above removed?
>
>
>
>
>
> *Cheers !*
>
>
>
> *WANG Weibin*
>
> _______________________________________________
> spring mailing list
> spring@ietf.org
> https://www.ietf.org/mailman/listinfo/spring
> <https://urldefense.com/v3/__https:/www.ietf.org/mailman/listinfo/spring__;!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JI97MuU_$>
>
> --
>
> Gyan S. Mishra
>
> IT Network Engineering & Technology
>
> Verizon Communications Inc. (VZ)
>
> 13101 Columbia Pike
> <https://www.google.com/maps/search/13101+Columbia+Pike?entry=gmail&source=g>
> FDC1 3rd Floor
>
> Silver Spring, MD 20904
>
> United States
>
> Phone: 301 502-1347
>
> Email: gyan.s.mishra@verizon.com
>
> www.linkedin.com/in/networking-technologies-consultant
> <https://urldefense.com/v3/__http:/www.linkedin.com/in/networking-technologies-consultant__;!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JI36IPfx$>
>
>
>
> --
>
> Gyan S. Mishra
>
> IT Network Engineering & Technology
>
> Verizon Communications Inc. (VZ)
>
> 13101 Columbia Pike
> <https://www.google.com/maps/search/13101+Columbia+Pike?entry=gmail&source=g>
> FDC1 3rd Floor
>
> Silver Spring, MD 20904
>
> United States
>
> Phone: 301 502-1347
>
> Email: gyan.s.mishra@verizon.com
>
> www.linkedin.com/in/networking-technologies-consultant
> <https://urldefense.com/v3/__http:/www.linkedin.com/in/networking-technologies-consultant__;!!NEt6yMaO-gk!QzHlcRglDrowIq4p7kbUU8tNwsbwrneoRiLDYAClyLIXp1ZLWOSxDhU6JI36IPfx$>
>
>
>
-- 

Gyan S. Mishra

IT Network Engineering & Technology

Verizon Communications Inc. (VZ)

13101 Columbia Pike FDC1 3rd Floor

Silver Spring, MD 20904

United States

Phone: 301 502-1347

Email: gyan.s.mishra@verizon.com

www.linkedin.com/in/networking-technologies-consultant