Re: [irs-discuss] IRS comments
Thomas Nadeau <tnadeau@juniper.net> Fri, 31 August 2012 22:58 UTC
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From: Thomas Nadeau <tnadeau@juniper.net>
To: Alia Atlas <akatlas@gmail.com>, Edward Crabbe <edc@google.com>
Date: Fri, 31 Aug 2012 18:56:58 -0400
Thread-Topic: [irs-discuss] IRS comments
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Cc: David Meyer <dmm@1-4-5.net>, "UTTARO, JAMES" <ju1738@att.com>, "Dutta, Pranjal K (Pranjal)" <pranjal.dutta@alcatel-lucent.com>, "Shah, Himanshu" <hshah@ciena.com>, "irs-discuss@ietf.org" <irs-discuss@ietf.org>
Subject: Re: [irs-discuss] IRS comments
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On 8/30/12 8:43 PM, "Alia Atlas" <akatlas@gmail.com> wrote: >On the encap/decap, I certainly view encap as simply a different type >of next-hop that a route to the RIB can have. Similarly, one can view >decap as treating a particular label/prefix - though that may require >more complexity. As well as also recursing to look into another table. For example, l3 vrfs connected to VPLS. >Negotiation is another area to think about too. Clearly, there will >be some capability negotiation needed as part of IRS - as well as the >ability to query for what capabilities are supported by the routing >element. I would rather do capability advertisement rather than negotiation. That is, agents should be able to understand what sorts of bits, knobs and buttons they can fiddle with, but I do not think it is important to have a full negotiation between the IRS agent and client about the diffs. Lets keep things as simple as possible. --Tom >Incidentally, if you are interested in writing down your thoughts >around different architectures for where parts of the routing system >might live and how they should/would interact with IRS, I'd encourage >you to do so and to chat with Dave Meyer, who has agreed to take on >looking at such pieces. > >While I do think that migrating the entire routing system except for >RIB off of a routing element would be for rather specialized >environments, I am also concerned that we consider the different >architectural possibilities when defining IRS so that we don't end up >going down an insufficient path. > >Alia > >On Thu, Aug 30, 2012 at 9:16 PM, Edward Crabbe <edc@google.com> wrote: >> Yep; not having to run an IGP on the box, which is great for those >>people >> not wanting / needing core internet protocols on their devices. The >> standard set of 'SDN' talking appoints applies here in terms of >>development >> speed, performance improvements resulting from use of modern commodity >> compute, friendliness of development environment, potential for >>decreased >> bug count* etc etc. >> >> It's a specialized use case, but it exists. >> >> However, my fundamental point is that with IRS as defined currently (ie >>PBR >> with extensible match fields on on RIB recursion + additional >>monitoring and >> data collection hooks) you can do hypothetically do away with IGPs. >>Indeed, >> assuming that the encaps is applied at some other device (since IRS as >> currently described doesn't account for encap/decap application or >> negotiation functionality) you can effectively replace a significant >>number >> of protocols (including stateful PCE) should you want to. :P >> >> <can of worms> >> >> *The benefits in terms of decreased bug counts above is really varies >>with >> how complex we make IRS of course. >> >> On Thu, Aug 30, 2012 at 6:01 PM, Dutta, Pranjal K (Pranjal) >> <pranjal.dutta@alcatel-lucent.com> wrote: >>> >>> Yep, the context of our original discussion was never PCE as we >>>understand >>> its CSPF or some form like that. Our concern was is there a strong >>>use >>> >>> case for non-constrained SPF? >>> >>> >>> >>> ________________________________ >>> >>> From: Edward Crabbe [mailto:edc@google.com] >>> Sent: Thursday, August 30, 2012 5:34 PM >>> >>> >>> To: Dutta, Pranjal K (Pranjal) >>> Cc: Alia Atlas; UTTARO, JAMES; Shah, Himanshu; irs-discuss@ietf.org >>> Subject: Re: [irs-discuss] IRS comments >>> >>> >>> >>> Nope, not specifically, but it strongly implies that there is some >>>form of >>> SPF running given the use of constraints in the draft. >>> >>> On Thu, Aug 30, 2012 at 4:16 PM, Dutta, Pranjal K (Pranjal) >>> <pranjal.dutta@alcatel-lucent.com> wrote: >>> >>> That doesn¹t talk about centralized SPF, does it ? >>> >>> >>> >>> ________________________________ >>> >>> From: Edward Crabbe [mailto:edc@google.com] >>> Sent: Thursday, August 30, 2012 4:12 PM >>> >>> >>> To: Dutta, Pranjal K (Pranjal) >>> Cc: Alia Atlas; UTTARO, JAMES; Shah, Himanshu; irs-discuss@ietf.org >>> Subject: Re: [irs-discuss] IRS comments >>> >>> >>> >>> http://tools.ietf.org/html/draft-ietf-pce-stateful-pce-01 >>> >>> On Thu, Aug 30, 2012 at 4:09 PM, Dutta, Pranjal K (Pranjal) >>> <pranjal.dutta@alcatel-lucent.com> wrote: >>> >>> Œoperational model¹ = IETF draft that describes the use case. >>> >>> Œlarge¹ = 40K LSAs, 500 IGP nodes. >>> >>> >>> >>> ________________________________ >>> >>> From: Edward Crabbe [mailto:edc@google.com] >>> Sent: Thursday, August 30, 2012 2:44 PM >>> >>> >>> To: Dutta, Pranjal K (Pranjal) >>> >>> Cc: Alia Atlas; UTTARO, JAMES; Shah, Himanshu; irs-discuss@ietf.org >>> >>> >>> Subject: Re: [irs-discuss] IRS comments >>> >>> >>> >>> please define 'operational model' ( and 'large' :) . >>> >>> On Thu, Aug 30, 2012 at 1:40 PM, Dutta, Pranjal K (Pranjal) >>> <pranjal.dutta@alcatel-lucent.com> wrote: >>> >>> Hi, >>> >>> I believe that¹s 10% of what overall work that router does >>>today >>> w.r.t routing. I would like to see an operational model how such >>>centralized >>> SPF can >>> >>> provide end-to-end convergence of large number of flows efficiently. >>> >>> >>> >>> Thanks, >>> >>> Pranjal >>> >>> >>> >>> ________________________________ >>> >>> From: Edward Crabbe [mailto:edc@google.com] >>> Sent: Thursday, August 30, 2012 11:59 AM >>> To: Alia Atlas >>> Cc: Dutta, Pranjal K (Pranjal); UTTARO, JAMES; Shah, Himanshu; >>> irs-discuss@ietf.org >>> >>> >>> Subject: Re: [irs-discuss] IRS comments >>> >>> >>> >>> Alia; >>> >>> >>> >>> If there is >>> >>> >>> >>> a) a mechanism for installing routes, pbr or otherwise, which recurse >>>to >>> directly connected nexthops >>> >>> b) a mechanism for gathering topological information >>> >>> >>> >>> then you've inherently enabled centralized spf. >>> >>> >>> >>> On Thu, Aug 16, 2012 at 9:34 AM, Alia Atlas <akatlas@gmail.com> wrote: >>> >>> I haven't seen a good description of what is intended or desired by >>> moving the SPF functionality to a centralized location. Clearly such >>> centralization can have a very bad impact on convergence - which is a >>> strong motivator for simultaneously computing fast-reroute >>> alternatives (with guaranteed coverage ala MRT) and installing both. >>> >>> I don't see IRS as having a way of "turning off" the SPF computation >>> in the IGP; a different lobotomized IGP protocol/process would be >>> needed. >>> >>> Alia >>> >>> >>> On Thu, Aug 16, 2012 at 12:14 PM, Dutta, Pranjal K (Pranjal) >>> <pranjal.dutta@alcatel-lucent.com> wrote: >>> > "LSDB (I saw an email which talks about reducing IGP to link >>> >> distribution protocol and running SPF in centralized network >>> >> controller)" >>> > >>> > I have seen discussions in the past on this and in fact I didn't get >>> > precisely what is meant. If anybody in the list could brief very >>> > precisely that would help a lot. >>> > >>> > Here is my understanding - the routers would do LSA/LSP flooding for >>> > OSPF/ISIS as it is done today. So routers would build neighboring >>> > relationship/adjacencies to participate in flooding and each router >>>builds >>> > its LSDB. >>> > >>> > Then the IRS "application" would track LSDB changes and pull up the >>> > "diffs" from each router (thru "controller") whenever there is a >>>change. The >>> > application would compute SPF on behalf of each router (LSDB). The >>>result of >>> > the compute would be pushed by application to each Router (thru >>>controller) >>> > and inject entries into RIB. >>> > >>> > Is that correct? How different this going to be from PCE? >>> > >>> > If this is correct then perhaps we would like to ask what are the >>> > scalability numbers in LSDB we are talking about? >>> > >>> > The "application" would be running in a high performance server and >>>so >>> > SPF compute there is not an issue and perhaps it is good way to >>>synchronize >>> > FIB update (to a certain extent) to avoid u-loops etc. >>> > >>> > But when we are managing all routers in the purview of the >>>application, >>> > the computing power in each router is not uniform. To be realistic, >>>I have >>> > some concerns on how much "real-timeness" we could achieve between >>> > application and controllers on such proposals, esp. when scaling >>>numbers are >>> > high. This leads to higher time lag on inconsistency between >>>application SPF >>> > compute and FIB update. It's almost like the classic "slow peering" >>>issues >>> > with TCP like protocols - the high performance peer is slowed down >>>by low >>> > performance peer. >>> > >>> > Static route interface is good thing because it is a state that >>>persists >>> > longer. >>> > >>> > IGPs may be deployed in very dynamic environments where tight >>>coupling >>> > is desirable between SPF compute and FIB update. In scaled >>>environments the >>> > issue is less about SPF compute time and is more about synchronizing >>>the >>> > FIB. >>> > >>> > Running on-demand CSPF by IRS application may be fine because of >>> > persistency of RSVP-TE tunnels in dynamic environments. >>> > >>> > I apologize if I misunderstood the intent. >>> > >>> > Thanks, >>> > Pranjal >>> >>> ---snip--- >>> >>> _______________________________________________ >>> irs-discuss mailing list >>> irs-discuss@ietf.org >>> https://www.ietf.org/mailman/listinfo/irs-discuss >>> >>> >>> >>> >>> >>> >>> >>> >> >> >_______________________________________________ >irs-discuss mailing list >irs-discuss@ietf.org >https://www.ietf.org/mailman/listinfo/irs-discuss
- Re: [irs-discuss] IRS comments Thomas Nadeau
- Re: [irs-discuss] IRS comments Gert Grammel
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Gert Grammel
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Thomas Nadeau
- Re: [irs-discuss] IRS comments Lin Han
- Re: [irs-discuss] IRS comments Thomas Nadeau
- Re: [irs-discuss] IRS comments Thomas Nadeau
- Re: [irs-discuss] IRS comments Lin Han
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Lin Han
- Re: [irs-discuss] IRS comments Susan Hares
- Re: [irs-discuss] IRS comments Robert Raszuk
- Re: [irs-discuss] IRS comments Thomas Nadeau
- Re: [irs-discuss] IRS comments Gert Grammel
- Re: [irs-discuss] IRS comments Scott Whyte
- Re: [irs-discuss] IRS comments Susan Hares
- Re: [irs-discuss] IRS comments Gert Grammel
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Scott Whyte
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Shah, Himanshu
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Olen Stokes
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments David Lake (dlake)
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments David Lake (dlake)
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Olen Stokes
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments David Lake (dlake)
- Re: [irs-discuss] 答复: 答复: IRS comments Thomas Nadeau
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Shah, Himanshu
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Olen Stokes
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Robert Raszuk
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Shah, Himanshu
- Re: [irs-discuss] IRS comments UTTARO, JAMES
- Re: [irs-discuss] IRS comments Lin Han
- Re: [irs-discuss] IRS comments Shah, Himanshu
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments Shah, Himanshu
- Re: [irs-discuss] IRS comments Shah, Himanshu
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments Ramon Casellas
- Re: [irs-discuss] IRS comments Shah, Himanshu
- Re: [irs-discuss] IRS comments Shah, Himanshu
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- [irs-discuss] 答复: IRS comments Mach Chen
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] 答复: IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- [irs-discuss] 答复: 答复: IRS comments Mach Chen
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] 答复: 答复: IRS comments Alia Atlas
- [irs-discuss] 答复: 答复: 答复: IRS comments Mach Chen
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] 答复: 答复: IRS comments Thomas Nadeau
- Re: [irs-discuss] IRS comments Acee Lindem
- Re: [irs-discuss] 答复: 答复: IRS comments Susan Hares
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Dutta, Pranjal K (Pranjal)
- Re: [irs-discuss] IRS comments Edward Crabbe
- Re: [irs-discuss] IRS comments Alia Atlas
- Re: [irs-discuss] IRS comments Thomas Nadeau