Re: [spring] Question from SPRING regarding draft-filsfilscheng-spring-srv6-srh-compression
Stefano Salsano <stefano.salsano@uniroma2.it> Sat, 23 October 2021 00:30 UTC
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To: Nick Hilliard <nick@foobar.org>
Cc: ipv6@ietf.org, SPRING WG List <spring@ietf.org>
References: <6865E218-00B1-41F0-9386-7B8F6DB1D776@steffann.nl> <3b9416b4-be73-c1a7-9235-7e832aee1657@foobar.org> <b5fc429e-2b72-84c6-503c-d623a90598fb@uniroma2.it> <78937788-5873-b89a-83a0-b93cc51223e9@foobar.org>
From: Stefano Salsano <stefano.salsano@uniroma2.it>
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Date: Sat, 23 Oct 2021 02:29:32 +0200
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Subject: Re: [spring] Question from SPRING regarding draft-filsfilscheng-spring-srv6-srh-compression
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Il 2021-10-21 12:02, Nick Hilliard ha scritto: > Hi Stefano, > > [spring@ re-added to cc:] > > Stefano Salsano wrote on 20/10/2021 22:36: >> I can anticipate that it is possible to use wireshark to dissect CSID >> packets, by providing very simple configuration information. > > This is exactly the problem though - operators will need to manually > instruct a dissector how to interpret the packet contents and that > defeats the purpose of a debugging tool because the tool is supposed to > be able to objectively tell you what's going on, without the operator > having to tell it what's going on. > > In particular, if you're attempt to debug a problem relating to C-SID > length, it would be completely useless. > > For example, how would you dissect the following sequence of compressed > SIDs of different lengths? > > 0x53b7e4f4d23b > > The short answer is you can't objectively, yet this could be a valid SID > argument. Hi Nick, the draft recommends to use a single CSID length (16 bits for NEXT, 32 bits for REPLACE), and if an operator also chooses a single block length it's very easy to provide the wireshark extensions to dissect all CSID containers in your domain if an operator wants to combine CSIDs of different length, building the debug tools becomes more complex, but this actually depends on the specific choices and configurations SRv6 is confined to an operator's domain, so an operator will have to debug SRv6 packets that have been created by nodes under the control of the operator and following the configuration choices of the operator Stefano > There's an opportunity at this point to ensure that whatever compressed > SID mechanism is implemented, that it's done in such a way if difference > lengths of compressed SIDs are allowed, that the SID length is included > in the encoding. > > If this isn't done, it will create a mess which operations and support > people will be stuck with for the lifetime of SRv6. Note that this > devalues SRv6 as an infrastructure component. > > Nick -- ******************************************************************* Stefano Salsano Professore Associato Dipartimento Ingegneria Elettronica Universita' di Roma Tor Vergata Viale Politecnico, 1 - 00133 Roma - ITALY http://netgroup.uniroma2.it/Stefano_Salsano/ E-mail : stefano.salsano@uniroma2.it Cell. : +39 320 4307310 Office : (Tel.) +39 06 72597770 (Fax.) +39 06 72597435 *******************************************************************
- Re: [spring] Question from SPRING regarding draft… Stefano Salsano
- [spring] Question from SPRING regarding draft-fil… Joel M. Halpern
- [spring] Typo correction Re: Question from SPRING… Joel M. Halpern
- Re: [spring] Typo correction Re: Question from SP… Brian E Carpenter
- Re: [spring] Typo correction Re: Question from SP… Michael Richardson
- Re: [spring] Typo correction Re: Question from SP… Ted Hardie
- Re: [spring] Typo correction Re: Question from SP… Carsten Bormann
- Re: [spring] Question from SPRING regarding draft… Erik Kline
- Re: [spring] Typo correction Re: Question from SP… Brian E Carpenter
- Re: [spring] Typo correction Re: Question from SP… Tom Herbert
- Re: [spring] Typo correction Re: Question from SP… mohamed.boucadair
- Re: [spring] Typo correction Re: Question from SP… Mark Smith
- Re: [spring] Typo correction Re: Question from SP… mohamed.boucadair
- Re: [spring] Typo correction Re: Question from SP… Ted Hardie
- [spring] short term plan regarding adoption call … Joel M. Halpern
- Re: [spring] Typo correction Re: Question from SP… Tom Herbert
- Re: [spring] Question from SPRING regarding draft… Andrew Alston
- Re: [spring] Question from SPRING regarding draft… Francois Clad (fclad)
- Re: [spring] Typo correction Re: Question from SP… Michael Richardson
- Re: [spring] Typo correction Re: Question from SP… Brian E Carpenter
- [spring] All IPv6 fields are now mutable (Re: Typ… Mark Smith
- Re: [spring] Question from SPRING regarding draft… Brian E Carpenter
- Re: [spring] Question from SPRING regarding draft… Brian E Carpenter
- Re: [spring] All IPv6 fields are now mutable (Re:… Andrew Alston
- Re: [spring] Question from SPRING regarding draft… Mark Smith
- Re: [spring] Question from SPRING regarding draft… Brian Carpenter
- Re: [spring] Question from SPRING regarding draft… Michael Richardson
- Re: [spring] Question from SPRING regarding draft… Darren Dukes (ddukes)
- Re: [spring] All IPv6 fields are now mutable (Re:… Tom Herbert
- Re: [spring] Question from SPRING regarding draft… Brian E Carpenter
- Re: [spring] All IPv6 fields are now mutable (Re:… Brian E Carpenter
- Re: [spring] Question from SPRING regarding draft… Nick Hilliard
- Re: [spring] All IPv6 fields are now mutable (Re:… Tom Herbert
- Re: [spring] Question from SPRING regarding draft… Darren Dukes (ddukes)
- Re: [spring] Question from SPRING regarding draft… Brian E Carpenter
- Re: [spring] All IPv6 fields are now mutable (Re:… Brian E Carpenter
- Re: [spring] Question from SPRING regarding draft… otroan
- Re: [spring] Typo correction Re: Question from SP… Ted Hardie
- Re: [spring] Typo correction Re: Question from SP… Brian E Carpenter
- Re: [spring] Typo correction Re: Question from SP… Brian E Carpenter
- Re: [spring] Typo correction Re: Question from SP… Mark Smith
- [spring] Administrative interfaces (was draft-fil… Ted Hardie
- Re: [spring] Administrative interfaces (was draft… Robert Raszuk
- Re: [spring] Typo correction Re: Question from SP… Tom Herbert
- Re: [spring] Typo correction Re: Question from SP… Brian E Carpenter
- Re: [spring] Typo correction Re: Question from SP… Greg Mirsky
- Re: [spring] Typo correction Re: Question from SP… Brian E Carpenter
- Re: [spring] Question from SPRING regarding draft… Nick Hilliard
- Re: [spring] Typo correction Re: Question from SP… Darren Dukes (ddukes)
- Re: [spring] Typo correction Re: Question from SP… Gyan Mishra
- Re: [spring] Typo correction Re: Question from SP… Gyan Mishra
- Re: [spring] Typo correction Re: Question from SP… Chengli (Cheng Li)
- Re: [spring] Typo correction Re: Question from SP… Darren Dukes (ddukes)
- Re: [spring] Question from SPRING regarding draft… Erik Kline
- Re: [spring] Typo correction Re: Question from SP… Gyan Mishra
- Re: [spring] Typo correction Re: Question from SP… Greg Mirsky
- Re: [spring] Typo correction Re: Question from SP… Darren Dukes (ddukes)
- Re: [spring] Typo correction Re: Question from SP… Erik Kline
- Re: [spring] Typo correction Re: Question from SP… Erik Kline