Subject: [OSPF] OSPF NBMA interface type

From: Glen Kent <[email-masked]>
Date: Fri, 5 Jul 2013 12:23:28 +0530

Hi,

These days people only have OSPF interface type as point-to-point and
broadcast. I understand that NBMA was required for technologies that
inherently dont support bcast, but where packets need to be sent to
multiple nodes (like ATM).

Given that ATM and Frame Relay networks are mostly out, when would we use
an OSPF interface type as NBMA or point-to-multipoint.

Is it in some wireless domains that we will use this?

Glen

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From: Acee Lindem <[email-masked]>
Date: Fri, 5 Jul 2013 13:29:25 +0000

Hi Glen,
With the convergence to ethernet everywhere, there is much less of a requirement for other OSPF topologies. However, P2MP is still very relevant in wireless and we now have the hybrid interface (RFC 6845). With Ericsson IPOS, we also use P2MP for subscriber OSPF adjacencies where a single interface can support many subscribers each with some form of explicit or implied encap for demuxing each individual subscriber.

I don't see much requirement for NBMA but I'm sure there are deployments making use of it.  

Thanks,
Acee 

On Jul 5, 2013, at 2:53 AM, Glen Kent wrote:

> Hi,
> 
> These days people only have OSPF interface type as point-to-point and broadcast. I understand that NBMA was required for technologies that inherently dont support bcast, but where packets need to be sent to multiple nodes (like ATM).
> 
> Given that ATM and Frame Relay networks are mostly out, when would we use an OSPF interface type as NBMA or point-to-multipoint.
>

---

From: "Russ White" <[email-masked]>
Date: Sat, 6 Jul 2013 08:35:59 -0400

> With the convergence to ethernet everywhere, there is much less of a
> requirement for other OSPF topologies. However, P2MP is still very
relevant
> in wireless and we now have the hybrid interface (RFC 6845). With Ericsson
> IPOS, we also use P2MP for subscriber OSPF adjacencies where a single
> interface can support many subscribers each with some form of explicit or
> implied encap for demuxing each individual subscriber.
> 

I would be opposed to removing it, even if I can't find many specific
instances of it being used (although MANET is a major use case) --unless we
could find some specific reason to remove it (i.e., improvements in
performance, reduced complexity that directly impacts the operation of
neighbor formation, etc.). 

Russ

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From: Acee Lindem <[email-masked]>
Date: Sat, 6 Jul 2013 13:59:52 -0400

Hey Russ,

On Jul 6, 2013, at 8:35 AM, Russ White wrote:

> instances of it being used (although MANET is a major use case)

OSPF MANET is has its own interface type (or should I say types since we have multiple experimental RFCs). They are all closer to P2MP than NBMA. 

> --unless we

There is a lot machinery to support NBMA adjacency formation and polling. If we were ever to do OSPFv4, I think it would be on the table for deprecation. 

Thanks,
Acee

> 
> Russ
> 
> 
> _______________________________________________
> OSPF mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/ospf

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From: "Russ White" <[email-masked]>
Date: Sat, 6 Jul 2013 14:24:32 -0400

> OSPF MANET is has its own interface type (or should I say types since we
> have multiple experimental RFCs). They are all closer to P2MP than NBMA.

Yes, that's true --actually, I'd forgotten about the use of the P2MP type in
the MANET space.

> There is a lot machinery to support NBMA adjacency formation and polling.
If
> we were ever to do OSPFv4, I think it would be on the table for
deprecation.

Sure --if we're starting on a new protocol version, yes. Deprecating it in
the current versions doesn't seem like it's worth the trouble (IMHO).

:-)

Russ

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From: Acee Lindem <[email-masked]>
Date: Sat, 6 Jul 2013 14:31:04 -0400

> the current versions doesn't seem like it's worth the trouble (IMHO).

I agree. 

Thanks,
Acee