Subject: [manet] dlep-01

From: "William D. Ivancic" <[email-masked]>
Date: Tue, 26 Jul 2011 16:21:27 -0400

A couple of comments and questions regarding draft-ietf-manet-dlep-01

Section 1.1 is entitled Requirements.  I suggest that be Terminology or
Required Language or something similar.  As is, the title does not fit
IMHO.

Figure 1 doesn't appear to match this statement in the assumptions.

   "DLEP assumes that participating modem devices appear to the router
   as a transparent bridge - specifically, the assumption is that the
   destination MAC address for data traffic in any frame emitted by
   the router should be the MAC address of the next-hop router or end-
   device, and not the MAC address of any of the intervening modem
   devices."

However, I think figure 1 is correct and the assumption is not a correct one.  

I think if I run a satellite modem such as a ViaSat Linkway modem or a
EF-Data Comstream modem with an ethernet interface to the router, the
MAC will be the MAC of the modem, not the downstream router.

Am I missing something?

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From: Teco Boot <[email-masked]>
Date: Tue, 26 Jul 2011 22:59:49 +0200

Figure 1 depicts a setup with 6 MAC addresses.
User traffic is router to router, the assumption is that the MAC address corresponding to the next-hop IP is the far-end router.
4 MAC addresses in the middle are for the two transparent bridges, with MAC address on each interface.
DLEP is between the router and local bridge. Could be IP also.

Note that pure 802.11 in IBSS (ad hoc mode) has difficulties with running in bridge mode. There are work-arounds.

Teco.

Op 26 jul 2011, om 22:21 heeft William D. Ivancic het volgende geschreven:

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From: Stan Ratliff <[email-masked]>
Date: Tue, 26 Jul 2011 20:22:43 -0400

William/Teco -

In the deployments we've tested in, the MAC address used is the one of  
the far-end router, instead of any of the intermediate devices (e.g.  
the satellite modems). I believe the sat modems act in bridging mode.  
I will say, however, I'm not experienced withe the EF-Data Comstream  
modem you mentioned. I'll look around and see what I can find on it.

Regards,
Stan

On Jul 26, 2011, at 4:59 PM, Teco Boot wrote:

> User traffic is router to router, the assumption is that the MAC  
> address corresponding to the next-hop IP is the far-end router.
> Note that pure 802.11 in IBSS (ad hoc mode) has difficulties with  
> running in bridge mode. There are work-arounds.
>
> Teco.
>

---

From: Teco Boot <[email-masked]>
Date: Wed, 27 Jul 2011 14:54:42 +0200

I did see a satcom modem vender switching from bridging to 
routing mode. This has a large impact on the network design. 
Impact on DLEP would be low, or none.

Teco

Op 27 jul 2011, om 02:22 heeft Stan Ratliff het volgende geschreven:

> William/Teco -
> 
> In the deployments we've tested in, the MAC address used is the one of the far-end router, instead of any of the intermediate devices (e.g. the satellite modems). I believe the sat modems act in bridging mode. I will say, however, I'm not experienced withe the EF-Data Comstream modem you mentioned. I'll look around and see what I can find on it.
> 
> Regards,
> Stan
>

---

From: Stan Ratliff <[email-masked]>
Date: Wed, 27 Jul 2011 10:30:53 -0400

Teco,

If, for instance, the satcom modem is truly in a "routing mode" - e.g.  
it has an OSI layer 3 routing protocol - then yes, things change  
dramatically. In that environment, any router directly connected to  
the satcom modem would simply establish a Layer 3 routing adjacency  
with the modem. For example, both the satcom modem and any directly  
attached router would run OLSR, and would exchange HELLO messages, and  
establish an OLSR adjacency. It would then be up to the satcom modem  
to take its variable metrics via some mechanism (a DLEP implementation  
running completely within the confines of the modem, for example), and  
advertise the appropriate route cost back to the router.

Regards,
Stan

On Jul 27, 2011, at 8:54 AM, Teco Boot wrote:

>> In the deployments we've tested in, the MAC address used is the one  
>> of the far-end router, instead of any of the intermediate devices  
>> (e.g. the satellite modems). I believe the sat modems act in  
>> bridging mode. I will say, however, I'm not experienced withe the  
>> EF-Data Comstream modem you mentioned. I'll look around and see  
>> what I can find on it.
>>
>> Regards,
>> Stan
>>

---

From: Teco Boot <[email-masked]>
Date: Wed, 27 Jul 2011 17:17:01 +0200

Running a routing protocol and form adjacency is one option.
Using the satcom terminal as gateway is another, more common
approach. Other options may exist.
DLEP can be used to set a metric on the default gateway route, 
or on a tunnel over this satcom link. 

Teco

Op 27 jul 2011, om 16:30 heeft Stan Ratliff het volgende geschreven:

> Teco,
> 
> If, for instance, the satcom modem is truly in a "routing mode" - e.g. it has an OSI layer 3 routing protocol - then yes, things change dramatically. In that environment, any router directly connected to the satcom modem would simply establish a Layer 3 routing adjacency with the modem. For example, both the satcom modem and any directly attached router would run OLSR, and would exchange HELLO messages, and establish an OLSR adjacency. It would then be up to the satcom modem to take its variable metrics via some mechanism (a DLEP implementation running completely within the confines of the modem, for example), and advertise the appropriate route cost back to the router.
> 
> Regards,
> Stan
>