Re: [lisp] LISP EID Block Size
"Joel M. Halpern" <jmh@joelhalpern.com> Sat, 02 November 2013 17:45 UTC
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Date: Sat, 02 Nov 2013 13:44:54 -0400
From: "Joel M. Halpern" <jmh@joelhalpern.com>
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To: Dino Farinacci <farinacci@gmail.com>
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Cc: LISP mailing list list <lisp@ietf.org>
Subject: Re: [lisp] LISP EID Block Size
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On the source side, the ITR had better know what EIDs it is working on behalf of (otherwise, it is a source for spoofed source address). So none of those cases seem to be affected by the allocation or non-allocation of a block. If we are going to do anything based on a block, we better make sure it can handle more than one block. Which means that at most we need a block for the duration of the test period. We do not need a block for the hoped for full success of LISP. If we really succeed, we can get an additional bigger block. Yours, Joel On 11/1/13 10:33 AM, Dino Farinacci wrote: >> I understand the importance of experimenting. But I am having >> trouble getting my head around the possible value we want to >> explore. Color me naive and stubborn, but individually so. >> >> Thinking about the ITR code path, if there is no block: > > Many are thinking in this context. It is one but there are other > things WE COULD DO if we new a prefix was an EID. See below for some > rough examples. And please don't ask for detail, because this is > initial thinking. > >> Receive packet check cache for destination failing cache match, >> query for destination. > > And there could be a failed match if the destination address was not > an EID. Meaning this packet is coming to an ITR destined for a > non-LISP site (regardless if the source address is an EID or not). So > the ITR would have to query the mapping database. > > So let's break this down. If the source was an EID, one could say, > "okay since I'm doing the new stuff the delay for a lookup to a > non-LISP destination is the price I pay for getting multihoming for > packets that come back to me". If the source was not an EID, then the > old user that expects to go to a non-LISP site expects the packet > loss or optimal routing path to continue. And if it does not, then > the new service hurt existing users. > > Please note, this is when a site is bifurcated being a site that has > some partial EID allocations and partial hosts that have not changed. > And that either could send to EID or non-EID destinations. > > Yes, you could have a default PETR configured in the ITR so there is > 0 packet loss, but then you may get a suboptimal path. And packets > from a non-EID source to a non-EID destination could be inadvertently > encapsulated to the PETR. Then the PETR would decap and deliver the > packet based on a BGP path. > > I for one, would like to solve this problem. And I do not know if > just a well-known, hard-coded, EID-block will do it. > >> And the ITR code path if there is a block: Receive packet check >> cache for destiantion failing cache match, check for destination in >> EID block If in EID block, query If not in EID block, query > > You are correct, but this box could be configured in way where the > logic could change: > > Receive packet If EID-block strict configured If destination in > EID-block, send query Else forward natively Else <do what Joel said > above with no EID-block check> Endif > >> Now, if everything is in the EID block, I understand that the last >> step above becomes "just send". But that appears to be a >> counter-factual assumption. >> >> Yours, Joel > > Having an EID block could help us in these scenarios as well: > > (1) The block or any more specifics should not have a native-forward > action in a Map-Reply returned by the mapping system. (2) The block > or any more specifics should not be injected into BGP without a > special community indicating that only PITRs should be advertising > it. (3) If a destination that a NAT box receives has a source in this > block, that translation should not be done (because it is not > needed). (4) If the source is in this block we know we cannot build > RPF trees in the core when the source sends multicast packets. (5) > Maybe a special EID-block should indicate that this source host can > only talk IPv6 and that stretched layer-2 subnets are prohibited. So > if you hit a box that does VXLAN and LISP, that layer 3 LISP is used > and we don't move MAC frames across the underly and we certainly do > not forward ARP packet, broadcast frames, and link-local multicast. > > Now all these things can be put in the mapping database, and give us > the same answers but if we could keep load off the mapping database, > this would be a good thing, a scalability feature. > > Dino > >> >> On 10/31/13 7:19 PM, Dino Farinacci wrote: >>>> >>>> Actually, that use case is only helped by the EID block if you >>>> can be sure that ALL the destination EIDs it will see will come >>>> from the block. >>> >>> I don't believe so. It could just an efficiency play for one >>> versus the other. >>> >>>> Which seems to be impossible to ensure in the general case. >>>> And easy to achieve without an allocated block in many of the >>>> special cases. >>> >>> Well the EID could mean it is behind a NAT and that ITRs should >>> encapsulate to an RTR. Maybe one that is used by a default >>> map-cache entry or a distinguished key on the mapping database. >>> >>> See there are sorts of things we could try. Again, "try" here >>> means experimentation. >>> >>> Look how the pilot network was easier to debug since we had >>> 153.16.0.0/16 generically donated by Andrew Partan and how cisco >>> has been renting 2610:d0::/32. >>> >>> Dino >>> >> _______________________________________________ lisp mailing list >> lisp@ietf.org https://www.ietf.org/mailman/listinfo/lisp > >
- [lisp] LISP EID Block Size Luigi Iannone
- Re: [lisp] LISP EID Block Size Noel Chiappa
- Re: [lisp] LISP EID Block Size Geoff Huston
- Re: [lisp] LISP EID Block Size Sander Steffann
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Rene Bartsch
- Re: [lisp] LISP EID Block Size Noel Chiappa
- Re: [lisp] LISP EID Block Size Noel Chiappa
- Re: [lisp] LISP EID Block Size Sander Steffann
- Re: [lisp] LISP EID Block Size Rene Bartsch
- Re: [lisp] LISP EID Block Size Noel Chiappa
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Rene Bartsch
- Re: [lisp] LISP EID Block Size Sander Steffann
- Re: [lisp] LISP EID Block Size Rene Bartsch
- Re: [lisp] LISP EID Block Size Noel Chiappa
- Re: [lisp] LISP EID Block Size Sander Steffann
- Re: [lisp] LISP EID Block Size Noel Chiappa
- Re: [lisp] LISP EID Block Size Joel M. Halpern
- Re: [lisp] LISP EID Block Size Roger Jørgensen
- Re: [lisp] LISP EID Block Size Darrel Lewis (darlewis)
- Re: [lisp] LISP EID Block Size Noel Chiappa
- Re: [lisp] LISP EID Block Size George Michaelson
- Re: [lisp] LISP EID Block Size Geoff Huston
- Re: [lisp] LISP EID Block Size Noel Chiappa
- Re: [lisp] LISP EID Block Size Noel Chiappa
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Joel M. Halpern
- Re: [lisp] LISP EID Block Size Rene Bartsch
- Re: [lisp] LISP EID Block Size Sander Steffann
- Re: [lisp] LISP EID Block Size Rene Bartsch
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Roger Jørgensen
- Re: [lisp] LISP EID Block Size Joel M. Halpern
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Luigi Iannone
- Re: [lisp] LISP EID Block Size Luigi Iannone
- Re: [lisp] LISP EID Block Size Sander Steffann
- Re: [lisp] LISP EID Block Size Luigi Iannone
- Re: [lisp] LISP EID Block Size Luigi Iannone
- Re: [lisp] LISP EID Block Size Luigi Iannone
- Re: [lisp] LISP EID Block Size Luigi Iannone
- Re: [lisp] LISP EID Block Size Luigi Iannone
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Joel M. Halpern
- Re: [lisp] LISP EID Block Size Geoff Huston
- Re: [lisp] LISP EID Block Size Luigi Iannone
- Re: [lisp] LISP EID Block Size Dino Farinacci
- Re: [lisp] LISP EID Block Size Darrel Lewis (darlewis)
- Re: [lisp] LISP EID Block Size Sander Steffann
- Re: [lisp] LISP EID Block Size Paul Vinciguerra
- Re: [lisp] LISP EID Block Size Darrel Lewis (darlewis)
- Re: [lisp] LISP EID Block Size Darrel Lewis (darlewis)
- Re: [lisp] LISP EID Block Size Paul Vinciguerra
- Re: [lisp] LISP EID Block Size Geoff Huston
- Re: [lisp] LISP EID Block Size Darrel Lewis (darlewis)
- Re: [lisp] LISP EID Block Size Rene Bartsch