Subject: [manet] DLEP and Peer MAC addresses

From: "Cheng, Bow-Nan - 0665 - MITLL" <[email-masked]>
Date: Thu, 23 Apr 2015 03:58:13 +0000

Hi everyone,

I remember a while ago some discussion about whether peer MAC addresses could be passed from the DLEP router to the DLEP modem/radio and couldn’t find/remember what the conclusion was.

One of the requirements of DLEP in destination messages is to pass the remote router’s MAC address to the locally connected DLEP router. While definition of how to get this remote router’s MAC over-the-air is beyond the scope of DLEP, I’m wondering if it makes sense to enable the local DLEP modem peer to know the locally connected DLEP router peer’s MAC address. This perhaps could be achieved by inclusion as an OPTIONAL field in the Peer Initialization.

I would say that you could ARP on the DLEP TCP session IP, but that would require exposing this externally to the DLEP client and then writing some extra code (outside of DLEP) to do the ARP or check neighbor tables. It seems like an extra step with additional code when DLEP should very well know this information.

Any thoughts on this? Thanks

-Bow-Nan

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From: Henning Rogge <[email-masked]>
Date: Thu, 23 Apr 2015 08:42:57 +0200

On Thu, Apr 23, 2015 at 5:58 AM, Cheng, Bow-Nan - 0665 - MITLL
<[email-masked]> wrote:
> Hi everyone,
>
> I remember a while ago some discussion about whether peer MAC addresses
> could be passed from the DLEP router to the DLEP modem/radio and couldn’t
> find/remember what the conclusion was.

I think this was me, trying to get Wifi IBSS (adhoc) mode working for
DLEP... because IBSS is not really capable of bridging, it would only
work if the MAC address of your router is the same as the MAC of your
wifi card.

Long story short:

don't use IBSS mode, use 802.11s with deactivated forwarding!

It gives you everything IBSS mode has, it plays nice with your wifi
hardware (no global TSF sync) and it supports bridging.

> One of the requirements of DLEP in destination messages is to pass the
> remote router’s MAC address to the locally connected DLEP router. While
> definition of how to get this remote router’s MAC over-the-air is beyond the
> scope of DLEP, I’m wondering if it makes sense to enable the local DLEP
> modem peer to know the locally connected DLEP router peer’s MAC address.
> This perhaps could be achieved by inclusion as an OPTIONAL field in the Peer
> Initialization.

You could also just look into the MAC header of the incoming UDP or
TCP packets from the router. Or you look into your local ARP table
after you established the TCP session... at the point you are
unicasting between radio and router, so both know each others MAC
address.

> I would say that you could ARP on the DLEP TCP session IP, but that would
> require exposing this externally to the DLEP client and then writing some
> extra code (outside of DLEP) to do the ARP or check neighbor tables. It
> seems like an extra step with additional code when DLEP should very well
> know this information.

Your OS already knows the MAC, otherwise the TCP session will not work.

Henning Rogge