Re: [OSPF] Adoption of "Single Hop MANET Interface" as WG Document

Richard Ogier <ogier@earthlink.net> Tue, 10 May 2011 05:24 UTC

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Date: Mon, 09 May 2011 22:25:37 -0700
From: Richard Ogier <ogier@earthlink.net>
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Subject: Re: [OSPF] Adoption of "Single Hop MANET Interface" as WG Document
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Alvaro,

One more point. If your network includes standard OSPF broadcast interfaces (which don't require a different cost for each pair of routers), then since RFC 5820 only specifies extensions for MANET interfaces, I assume you will not apply RFC 5820 to such broadcast networks, even though you could.

Similarly, if OSPF were already extended to the hybrid-bcast-p2mp interface type, then you would not need to apply RFC 5820 to such interfaces, even though you could, since a good solution would already exist.

My point is that we only need one solution for the hybrid broadcast interface type.  In fact, if we want to standardize OSPF extensions for both the hybrid broadcast and MANET interface types, we should decide on a SINGLE solution.  There is no reason not to have a single solution.

In fact, with the Router Priority heuristic described in draft-retana, this method becomes closer (but not the same) as hybrid-bcast-p2mp.  And I already mentioned the similarity of hybrid-bcast-p2mp to OSPF-MDR applied to a single-hop networks.  Therefore, the three approaches are already somewhat similar, so we should be able to agree on one of these.  In my opinion hybrid-bcast-p2mp is the simplest and involves the fewest changes to OSPF, so I propose that we all adopt that method for the hybrid broadcast interface type.

If you want to argue that it is not a new interface type, but is just a special case of the MANET interface, then you should not need to specify any changes to the MANET extension, and an Informational draft should be sufficient.  But you are proposing changes based on identifying the interface to be single-hop, so this can be considered a new interface type.  We have three similar solutions for this interface type, and we should be able to agree on one of these.

Richard

Retana, Alvaro wrote:
mid24646CE17826CF4A8DF71F9856C7E65659240FE447@GVW1338EXA.americas.hpqcorp.net" type="cite">

Richard:

 

You’re right to say that the MANET solution can handle the special case of a single-hop broadcast network, if one was encountered.  The deployment lesson that we’re taking from that scenario is that it is operationally simpler to work w/one type of interface: one neighbor discovery process, one interface description model, etc…specially in cases where the ability to configure and troubleshoot the network in the field is greatly reduced by both access to the nodes as well as the potential abilities of the operators, which is the case in some of the deployments of rfc5820.

 

IOW, in a mobile network that may include multi-hop and single-hop interfaces, it is operationally preferred to deploy just one type of interface model.

 

Thanks!

 

Alvaro.

 

From: Richard Ogier [mailto:ogier@earthlink.net]
Sent: Monday, May 09, 2011 4:19 PM
To: Retana, Alvaro
Cc: ospf@ietf.org
Subject: Re: [OSPF] Adoption of "Single Hop MANET Interface" as WG Document

 

In my opinion, the hybrid-bcast-and-p2mp draft is a simple and perfect solution to this problem:
http://tools.ietf.org/id/draft-nsheth-ospf-hybrid-bcast-and-p2mp-01.txt" rel="nofollow">http://tools.ietf.org/id/draft-nsheth-ospf-hybrid-bcast-and-p2mp-01.txt

This has been discussed and some of us agree with this.  For example, Jeffrey Zhang's post dated 4/11/2011 summarizes some of the arguments.

Although both RFC 5820 (OSPF-OR) and RFC 5614 (OSPF-MDR) can be applied to single-hop broadcast networks and thus solve the same problem as the hybrid-bcast-p2mp draft, the hybrid draft is clearly the simplest solution, involving minimal changes to OSPF.

If the network is definitely a single-hop network, so that each router is one hop from all other routers, then there is no need for a MANET solution.  Otherwise, we need a MANET solution, which will also handle the special case of a single-hop network if by chance the network is single-hop (and this can be mentioned in the MANET draft).

But I would never apply a MANET solution if the network is definitely a single-hop network; I would go with the simpler solution in the hybrid draft.  For this reason, I don't think it makes sense to propose applying an OSPF-MANET extension to the case of a single-hop broadcast network.  But if someone can describe a situation where it makes sense to do this, please do so.

Richard


Retana, Alvaro wrote:

Hi!

 

Following up on the WG meeting in Prague…

 

http://tools.ietf.org/html/draft-retana-ospf-manet-single-hop" rel="nofollow">http://tools.ietf.org/html/draft-retana-ospf-manet-single-hop

 

A brief poll at the meeting found no objection to this update to rfc 5820.

 

This e-mail is the formal request for adoption as a WG document.  Just like rfc 5820, the intended status is Experimental.

 

Thoughts/comments?

 

Thanks!

 

Alvaro.

 

 

 
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