[Softwires] Re: WG LC Problem Statement
Pekka Savola <pekkas@netcore.fi> Thu, 22 December 2005 07:45 UTC
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Date: Thu, 22 Dec 2005 09:45:27 +0200
From: Pekka Savola <pekkas@netcore.fi>
To: softwires@ietf.org
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Subject: [Softwires] Re: WG LC Problem Statement
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Hi, I've re-read the problem statement. Below are also those comments for the earlier version that didn't seem to be addressed but still seem applicable [1]). I do not think the problem statement can go forward in its current form. It clearly has not been read enough even by the co-authors as it has a number of typos, procedural omissions (failing ID-nits and so on) etc. But I'm hopeful that these and the couple of substantial issues could be fixed in one or two revisions and the doc could go forward around the January timeframe. substantial ----------- [1] -- the issue with the assumption that the connected islands have just one address family (instead of being dual-stack) is serious and requires significant rewording. The currently described problem is not the one described by CERNET. The rest of the comments are at the end of this mail. ... 3.2. Network Address Translation (NAT) and Port Address Translation (PAT) ... There is no requirement to be able to "autodetect" NAT or PAT presence during softwire setup. ==> I do not agree with this statement without further qualifiers. The softwire setup needs to work by default through a NAT, and the statement above does not really address that point. Suggest replacing with: Establishing a softwire through NAT or PAT must work by default. However, there is no requirement for explicitly "autodetect" NAT or PAT presence during softwire setup. I.e., unless the solution provides autodetection, it must be chosen in a manner that can traverse NAT/PAT. I think that's a hard requirement. ....... 3.7. Softwire Concentrator Discovery When the initiator of the softwire is a CPE, the IP address or DNS hostname of the softwire concentrator must be known. The simplest way for this to be known by the CPE is for it to be configured by the user, or by the provider of the CPE in advance. Alternatively, an automated discovery phase may be run in order to return the IP address(s), or hostname(s) of the concentrator. The details of this discovery problem are outside the scope of this document. ==> The first "When the initiator of the softwire is a CPE," is not true and should be removed or reworded. The same text applies (roughly) in all cases 1-3, though configuration is more difficult if the initiator is not CPE. The text needs to be generalized. It should be noted that according to reports the islands do not want to achieve network connectivity via tunneled Layer 2 mechanisms but, as distinct Layer 3 or MPLS routers. This clearly helps scaling and Layer 2 discovery performance issues. It also prevents having to have fully meshed point to point Layer 2 connectivity between the nodes in differing islands as Layer 2 technology choice must be preserved. ==> while one network might want to use Layer 3 mechanism, I do not think Layer 2 should be ruled out as it's a more generic solution. We should provide a solution for that as well. semi-editorial -------------- ==> in hub and spoke case 2 and case 3, isn't HGW typically v4-only (otherwise we'd be looking at case 1?), like follows: +-------+ +-------------+ +--------+ | | | Softwire | | IPv6 | +-----+ +-----+ | Pv4 |---| concentrator|--| Network| |Host |--| HGW |---| | +-------------+ +--------+ +-----+ +-----+ |Network| +-------+ _ _ _ _ _ _ _ _ _ _ _ _ ()_ _ _ _ _ _ _ _ _ _ _ _() "softwire" |-------|-------------------||-------------------------| Dual IPv4 only IPv6 or dual stack stack (however, it'd be possible for HGW be dual-stack but just not support setting up softwires..) 3.4. Static Prefix Delegation ==> split the first paragraph in 2 or 3. procedural issues ----------------- ==> it'd be appropriate to acknowledge the earlier problem statement work in this space -- at least draft-palet-v6tc-goals-tunneling-00, which includes references to even prior art. ==> a "null" IANA considerations section is needed. ==> the front page lists 6 authors. This is more than the maximum limit (5). I'd suggest just putting the editor on the front page. 7. References ==> need splitting to norm/informative ==> the referred docs (e.g., Steve Bellovin's IPsec recommendations) need to be added as explicit recommendations here. editorial --------- ==> spell out the terms when used the first time (at least, "ISP") multicast trafic. They are also assumed to be non-ephemeral in nature thus, they are peristent or long-lived. Last, the setup ==> s/trafic/traffic/ ==> s/peristent/persistent/ setup time of the CPE/Address Family Boundry Router (AFBR) ==> s/Boundry/Boundary/ ==> missing "." at the end. Section 5). The primary difference between these two problems are how many connections and associated routes are managed by each IPv4 ==> s/are/is/ number of well connected hubs and then deserve smaller airports ==> s/deserve/serve/ There are three cases refer to Hubs and Spokes problem which are shown in Diagram 1. ==> cannot parse "are three cases refer". Missing "that" ? contentrator. An ISP may deploy several concentrators (for example ==> s/content/concent/ a keepalive mechanism MUST be define. Such a mechanism is also ==> s/define/defined/ Other OAM needed features include: ==> s/OAM needed/needed OAM/ - Path failure detection) ==> remove ")" ? (both in section 3 and 4) differing address family type. For an example, See Figure 1. Note ==> it's figure 2. It should also be noted that the mesh problem can be treat as a ==> s/treat/treated/ In contrast with the hub and spoke problem, routers are advertizing routers for relatively large islands, and never a single user so there is no "user authentication" necessary. ==> "routers are advertizing routers" and ", and never a single user" -- reword this sentence. IPv6/IPv4,IPv4/IPv6 and overlapping address space as defined in the ==> s/,/, / ============== [[ earlier comments that still seem to be valid ]] 3.8. Scaling In a hub and spoke model, an ISP MUST scale the solution to millions of softwire inititators by adding more hubs (i.e. softwire concentrator). ==> s/MUST scale/must be able to scale/ (we cannot give upper-case requirements on what the ISPs do, and even so, it's a bit inappropriate to use upper-case keywords in a requirements document) - End-point failure detection (must be encapsulated w/in the tunnel in the transmitting direction ==> please clarify what you mean after '(', it's not clear. Reference Diagram ._._._._ ._._._._ | | | | | V4 | | V4 | |access | |access | |island | |island | ._._._._ ._._._._ ==> I don't think this was the case we were talking about. Shouldn't all the islands be dual-stack? This is pretty important consideration -- the key point emerges when an island with protocol X would like talk to an island with protocol Y. (where an island could be the rest of the internet as well). The AFBR's are the only devices in the network that must be able to perform dual-stack operations and setup and encapsulate softwires in a mesh to the other islands. ==> s/network/ISP's network/ -- the CPEs should obviously be dual-stack, right, so those could set up tunnels if they wished to. It should be noted that according to reports the islands do not want to achieve network connectivity via tunneled Layer 2 mechanisms but, as distinct Layer 3 or MPLS routers. This clearly helps scaling and Layer 2 discovery performance issues. ==> it isn't clear enough what this point means. ======================== _______________________________________________ Softwires mailing list Softwires@ietf.org https://www1.ietf.org/mailman/listinfo/softwires
- [Softwires] WG LC Problem Statement David Ward
- RE: [Softwires] WG LC Problem Statement BAUDOT Alain RD-CORE-CAE
- [Softwires] Re: WG LC Problem Statement Pekka Savola
- Re: [Softwires] Re: WG LC Problem Statement JORDI PALET MARTINEZ
- Re: [Softwires] Re: WG LC Problem Statement JORDI PALET MARTINEZ
- Re: [Softwires] WG LC Problem Statement Francis Dupont
- Re: [Softwires] WG LC Problem Statement Francis Dupont
- Re: [Softwires] WG LC Problem Statement (Alain Ba… Spencer Dawkins
- Re: [Softwires] WG LC Problem Statement JORDI PALET MARTINEZ
- Re: [Softwires] WG LC Problem Statement JORDI PALET MARTINEZ
- Re: [Softwires] WG LC Problem Statement Francis Dupont
- Re: [Softwires] WG LC Problem Statement Francis Dupont
- Re: [Softwires] WG LC Problem Statement JORDI PALET MARTINEZ
- Re: [Softwires] Re: WG LC Problem Statement (Pekk… Spencer Dawkins
- Re: [Softwires] WG LC Problem Statement (Francis … Spencer Dawkins
- Re: [Softwires] Re: WG LC Problem Statement (Pekk… Pekka Savola
- Re: [Softwires] WG LC Problem Statement (Francis … Spencer Dawkins