Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-multihoming-00.txt
Vasilenko Eduard <vasilenko.eduard@huawei.com> Mon, 06 March 2023 19:48 UTC
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From: Vasilenko Eduard <vasilenko.eduard@huawei.com>
To: Brian E Carpenter <brian.e.carpenter@gmail.com>, "v6ops@ietf.org" <v6ops@ietf.org>
Thread-Topic: [v6ops] I-D Action: draft-fbnvv-v6ops-site-multihoming-00.txt
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Date: Mon, 06 Mar 2023 19:48:38 +0000
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Subject: Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-multihoming-00.txt
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Hi Brian, I do not see a difference between static and dynamic PA allocation. In both cases deprecation for stale prefixes is mandatory. Just in the case of "dynamic non-permanent" (the next prefix is different after re-connect) it should be deprecated forever. But in the case of "dynamic permanent" or "static" (prefix would be the same after re-connect) it should be deprecated for hours till the fiber would be fixed. Or else would be a black hole. It is a very small difference (for how many hours to deprecate). Hence, I do not see a need for a separate section. The question in MH context is not a "static" vs "dynamic". It is "permanent" vs "non-permanent" (the same or not after re-connect). "Static" is always "permanent". "Dynamic" is "permanent" in 63% too. No difference at all. PS: Comment that "static" prefixes case is covered is needed in the draft. Eduard -----Original Message----- From: v6ops [mailto:v6ops-bounces@ietf.org] On Behalf Of Brian E Carpenter Sent: Sunday, March 5, 2023 12:54 AM To: Klaus Frank <klaus.frank@posteo.de>; v6ops@ietf.org Subject: Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-multihoming-00.txt Just a couple of extra comments where I was unclear in my first message: On 05-Mar-23 01:55, Klaus Frank wrote: > Hi > > On 04.03.2023 04:09, Brian E Carpenter wrote: >> Hi, >> >> Some comments (not really a full review): >> >> Firstly, thanks for starting this work, it is badly needed. >> >> Second, a bit off topic, but it was recently rediscovered where I >> live (New Zealand) that any amount of MHMP won't help you if your >> region is supplied by a single fibre trunk shared by all providers, >> and a landslide removes that trunk. It might be worth reminding >> readers of that. We really need MHMPMD (MD = multiple ducts). > You could still get Starlink as a redundant uplink for example. >> >> One of the four solutions reads: >> >> "- Dynamic PA addresses distribution and withdrawal from carriers" >> >> I think that is really hiding a more traditional solution, something >> like: >> >> - Static PA addresses from multiple carriers, chosen dynamically >> by hosts. > > No, thous two aren't the same. The first one is where the ISP also > occasionally assigns you a different one. So your PA prefix changes > dynamically. Or at least when your router reconnects. So it isn't a > static PA allocation at all. I expressed myself badly. I think you should in fact list 5 solutions, with "Static PA addresses" before "Dynamic PA addresses". Of course, even static prefixes are not static for ever, but for large enterprise networks a change of PA prefix would be a planned event (RFC4192) and the MHMP problem is simpler. I agree of course that the dynamic case must also be solved. > >> >> Dynamic prefix assignment and withdrawal is a *new* model. >> Whether it can be made to work is an open question. > We need it to work nonetheless, as providers often tier their services > to have dynamically allocating and therefore changing prefixes on the > cheaper contracts and often only offer static ones either at a higher > price at a very high price together with SD-WAN offerings... >> >> I'm ranting about this because whatever solution we propose must >> satisfy the needs of end hosts at least as well as it satisfies the >> needs of enterprise network operators and carriers. And that aspect >> isn't clear to me in the list that starts "4. Solution requirements". >> (I'd personally prefer a solution that requires no new action >> whatever by the carriers.) > > That's why we listed multiple. Our assumption was that Enterprises > will want to use their own PI prefix and either use a tunnel to a > centralized point (similar to LISP) or have SD-WAN contracts with the > ISP and be able to speak BGP with them to route the PI directly. > > Where as smaller and home entities may either use a service provider > (LISP), dual assignment of all the prefixes if it's a flat hierarchy > "plug both ISP routers into the same local network", or use a > (cheap/simple) load balance in front of the CPEs and do NAT/NPT on it. > >> >> One of the requirements: >> >> "4. Sub-second convergence for the prefix deprication..." >> >> comes out of nowhere. Won't this vary widely? In a small office >> network, why not 5 seconds or 30 seconds? In a stock trading data >> centre, wouldn't they want sub-millisecond convergence? > The intent behind this was to stay within the usual timeout windows of > higher protocols to allow for a re-transmission without a connection > error being user-facing. >> Also cover the case of redundant topologies (>1 router per subnet). > > Outside of the scope of this RFC and where relevant already covered. > If you have two redundant routers on the subnet, then they'll route it > towards the CPEs at some point. And at that point it is the same as if > it was a client that sent the package. Also we mentioned the concerns > about complex networks and what approach would allow for static > subnetting and which ones don't. > > The main issue this whole proposal is that ISPs don't offer BGP to > customers at an acceptable price point and that if everyone had their > own PI and would use BGP to the ISP that it would bloat the global > routing table. Another ideal world solution would be that IP addresses > are allocated by geographical area (and thereby allow route > aggregation using it) and not legal entity and a RPKI like approach > for the ISPs to assign IPs and allow customers to use any "RPKI-valid" > source prefix through their network and route it into the internet > even if it was assigned by another ISP. > > But that's all make believe and we have to deal with the cards we were > given, that's also why we explicitly mentioned issues with cellular > and NAT66... > >> "Privacy is furthermore assumed to be protected by [Temporary >> addressing] and is also kept outside of the carrier resiliency design >> consideration." >> >> I think that needs rewording. Some enterprises forbid temporary >> addresses, so the assumption is sometimes false. I think it would be >> safer to say that address-based privacy considerations are not >> affected by carrier resiliency in itself. (They might be affected by >> the choice to use or not use NAT66 or NPTv6, but that is a separate >> discussion.) >> >> "5.1. PI-based >> ... >> Advantages:" >> >> Isn't the #1 advantage: It works today! ? > > Because it doesn't like it should. It only works in principal but has > huge issues in practice for most people... > >> "Disadvantages: >> ... >> - Bloats the Internet routing table." >> >> How about >> >> - Bloats the Internet routing table with a potential 10 million new >> routes. ? >> >> I don't think we should make this solution sound satisfactory. > > Well, that still wouldn't be a concern of the entity that wants to > have redundancy. And ultimately we don't really have any solution that > doesn't have issues right now. > > The only real way to change this would be to completely rethink the > address assignment (see make believe above) and redo all of it, so > it's basically unavoidable/unsolvable at this point... > >> >> "5.2. PA-based solution >> ... >> It is mandatory to implement requirement L-13 of [HNCP] section 11 to >> deprecate delegated prefixes..." >> >> That reads as if you are proposing HNCP for everyone, which I am sure >> is not your intention. Can you rephrase it to sound like a property >> of the solution? > > It already is, as it is listed within 5.2 and all sub sections of 5 > are different individual solutions. Again I expressed myself badly. I don't disagree technically, but the current text can mislead the reader to believe that you are suggesting HNCP as the solution. I'm suggesting that your text should be something like: "As soon as a CE router becomes aware that the path to the carrier that delegated a prefix is down, it is necessary that all more specific prefixes under that prefix are deprecated (preferred lifetime set to zero) in all subnets. This is specified as requirement L-13 of [HNCP] but is not currently available in other routing mechanisms." This leads directly to a requirement statement for the general case, where HNCP is not relevant. Brian > And it is in fact mandatory to the solution 5.2. So if you want to use > the suggested PA-based solution you'll have to use it... > >> >> "Potentially, the application on the host may use bind() to choose >> the source address..." >> >> Yes, but most applications don't do that, they start with getaddrinfo(). >> So what is the value of this discussion of bind()? > Because it is an issue with application compatibility and the whole > point of this proposal is to have a resilient up-link to not have > applications loose internet link and have a solution that does not > break applications. So this case sadly has to be considered as it is > affecting too many applications to just be ignored. But I admit that > we'd need better statistics for that to not just be based on > individual experience, but we currently don't have such statistics nor > a good way to get them... >> >> "It may be valuable to implement [Provisioning domains]..." >> >> What is the probability of that happening? >> >> "Disadvantages: >> ... >> - Carriers may frequently change the prefix (flash renumbering), >> and >> this could disrupt communication" >> >> Why is that new? Many IPv6 carriers do that for SOHO users today. I >> think they don't do it for larger enterprises, though. > It depends, I know from the top of my head of at least one enterprise > that had within the IPv4 world it's redundant links on the cheapest > contract available. So they'd do it there as well... And within the > IPv4 world they also didn't have any real reason to get a more > expensive offer, as they accomplished the same SLA level by just > having multiple redundant up-links and saved a non significant amount > of money compared to using the more expensive contracts that didn't > and because they used > NAT44 the public IP change also didn't affect the internal network at > all. Even for the VPN connections between the sites they just used > dyndns and had the CPEs update the IP in DNS... >> >> "5.3. ULA with NPT >> ... >> However, [ULA] has >> notable limits concerning the number of sites that one prefix may >> span, and well documented usability limitations when considering >> address selection details across large, diverse network >> environments." >> >> I'm not sure these limits are "well documented". If they are, please >> give a reference. > * RFC6724 > * documentation of the major operating systems (Windows, MacOS, > Fedora, RedHat, ...) > * documentation of the major firewall vendors (PaloAlto, Sophos, > Cisco, ...) > * almost all it handbooks that talk about network fundamentals and > also include IPv6 > * countless blog posts with advice on how to configure IPv6 >> "5.4. ULA with NAT66 >> ... >> Advantages: >> ... >> - NAT may be a normative requirement in itself (this is highly >> questionable, but nonetheless brought forward in many >> discussions)" >> >> Note that PCI-DSS (version 4, March 2022) does not require NAT, >> although it is mentioned as a solution for IPv4. See >> https://docs-prv.pcisecuritystandards.org/PCI%20DSS/Standard/PCI-DSS- >> v4_0.pdf > That's exactly what we were referring to by "this is highly > questionable, but nonetheless brought forward in many discussions", > even here on the IETF lists there were discussions not even two months > ago of working together with regulatory entities to avoid (and where > it exists > currently) remove NAT66 requirements... >> >> " 6. Conclusion" >> >> I think in general this section is premature, until the earlier >> sections have been widely reviewed and updated. So mainly I will not comment, but: >> >> "For sites having a complex topology (many links and routers), a PA- >> based solution is not an option yet,..." >> >> Agreed, but: >> >> "... because it would need automatic >> PA address distribution over the site and neither [HNCP] nor >> DHCP-PD >> have gained market acceptance for this task." >> That is needed for flash renumbering, but NOT for a static multi-PA >> solution. There, the requirement is much simpler: prefix up/down >> status distribution over the site. That's close to a trivial problem >> to solve, if we decide to solve it. (For example, it would be easy to >> define a GRASP [RFC8990] method for it, and I'm sure there are ten >> other solutions waiting.) > > Right, we kinda neglected the part of having only static PA allocation > by the ISPs. Almost the whole draft is assuming that the PA prefix can > and will change without any upfront warning. But even if we for now > assume the PA allocated by every ISP is static, then we still have the > source address selection issue. As the ISPs still would filter the > packages that we push their way that have a Pa allocation of any of > the other ISPs in the mix... But I agree that in the case of static PA > allocations a customer could still do a full switch over to a > different link. It's only a active-passive setup. Still not ideal > (active-active with the ability for traffic engineering by the site > admin), but better than nothing for sure. > > Side note, please don't take this too serious right now, it's not > fully worked out, just something I had to think about reading your > reply to > this: What could help even in the case of multiple dynamic PA > allocations is if we'd have DHCP-PD solutions that could dynamically > update their configuration based on what the CPE provides (router > advertisement or DHCP-PD, also UPNPv6 could help if it was reliable > like it's IPv4 equivalent). But I don't think any network equipment > currently supports such a "feature" (but custom scripting on Linux may > work 🤔 > right now), but at the end that's just a worse implementation of what > we have right now. - Or is it? After all a solution that doesn't > involve the ISP or CPE is exactly what we need to unblock our selves > from these limitations... > >> >> Regards >> Brian Carpenter > > Thanks for your review of our proposal. > > Sincerely, > Klaus Frank > >> >> On 04-Mar-23 03:59, internet-drafts@ietf.org wrote: >>> >>> A New Internet-Draft is available from the on-line Internet-Drafts >>> directories. >>> >>> >>> Title : IPv6 Site connection to many Carriers >>> Authors : Nick Buraglio >>> Klaus Frank >>> Paolo Nero >>> Paolo Volpato >>> Eduard Vasilenko >>> Filename : draft-fbnvv-v6ops-site-multihoming-00.txt >>> Pages : 32 >>> Date : 2023-03-03 >>> >>> Abstract: >>> Carrier resilience is a typical business requirement. IPv4 >>> deployments have traditionally solved this challenge through >>> private >>> internal site addressing in combination with separate NAT >>> engines >>> attached to multiple redundant carriers. IPv6 brings support >>> for >>> true end-to-end connectivity on the Internet, and hence NAT is >>> the >>> least desirable option in such deployments. Native IPv6 >>> solutions >>> for carrier resiliency, however, have drawbacks. This document >>> discusses all currently-available options to organize carrier >>> resiliency for a site, their strengths and weaknesses, and >>> provides >>> a history of past IETF efforts approaching the issue. The views >>> presented here are the summary of discussions on the v6ops >>> mailing >>> list and are not just the personal opinion of the authors. >>> >>> >>> The IETF datatracker status page for this Internet-Draft is: >>> https://datatracker.ietf.org/doc/draft-fbnvv-v6ops-site-multihoming/ >>> >>> There is also an htmlized version available at: >>> https://datatracker.ietf.org/doc/html/draft-fbnvv-v6ops-site-multiho >>> ming-00 >>> >>> >>> >>> Internet-Drafts are also available by rsync at >>> rsync.ietf.org::internet-drafts >>> >>> >>> _______________________________________________ >>> I-D-Announce mailing list >>> I-D-Announce@ietf.org >>> https://www.ietf.org/mailman/listinfo/i-d-announce >>> Internet-Draft directories: http://www.ietf.org/shadow.html or >>> ftp://ftp.ietf.org/ietf/1shadow-sites.txt >> >> _______________________________________________ >> v6ops mailing list >> v6ops@ietf.org >> https://www.ietf.org/mailman/listinfo/v6ops >> >> _______________________________________________ >> v6ops mailing list >> v6ops@ietf.org >> https://www.ietf.org/mailman/listinfo/v6ops _______________________________________________ v6ops mailing list v6ops@ietf.org https://www.ietf.org/mailman/listinfo/v6ops
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Brian E Carpenter
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Klaus Frank
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Brian E Carpenter
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Ole Trøan
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Paolo
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Brian E Carpenter
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Nick Buraglio
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Brian E Carpenter
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Klaus Frank
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Paolo Nero
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Ole Trøan
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Brian E Carpenter
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Ole Trøan
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Brian E Carpenter
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Vasilenko Eduard
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Vasilenko Eduard
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Vasilenko Eduard
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Klaus Frank
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Vasilenko Eduard
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Paolo Nero
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Vasilenko Eduard
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Nick Buraglio
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Klaus Frank
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Ole Troan
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Klaus Frank
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Brian E Carpenter
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Gert Doering
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Ole Troan
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Klaus Frank
- Re: [v6ops] I-D Action: draft-fbnvv-v6ops-site-mu… Brian E Carpenter