Re: [manet] DLEP address semantics and in-the-wild examples

Rick Taylor <rick@tropicalstormsoftware.com> Fri, 12 November 2021 17:10 UTC

From: Rick Taylor <rick@tropicalstormsoftware.com>
To: "Sipos, Brian J." <Brian.Sipos@jhuapl.edu>, "manet@ietf.org" <manet@ietf.org>
CC: "Taylor, Rick" <rick.taylor@airbus.com>
Thread-Topic: DLEP address semantics and in-the-wild examples
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Date: Fri, 12 Nov 2021 17:10:07 +0000
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Subject: Re: [manet] DLEP address semantics and in-the-wild examples
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Hi Brian,

Your first assumption is correct.  The MAC address of the interface the router uses to maintain the DLEP session is the MAC address used as a Destination identifier by its peers.  DLEP does not (currently) define an 'out-of-band mode' where the DLEP session is maintained on a different MAC address from the data-plane.

One could define an out-of-band mode by a router using a Destination Up message with an alternate data-plane MAC address, but that is currently not defined anywhere.

Cheers,

Rick

From: manet [mailto:manet-bounces@ietf.org] On Behalf Of Sipos, Brian J.
Sent: 25 October 2021 16:05
To: manet@ietf.org
Cc: Taylor, Rick
Subject: [manet] DLEP address semantics and in-the-wild examples

All,
I am in the process of investigating and implementing a DLEP router component and trying to figure out which sets of data items are available for which contexts (peer session vs. destinations) and how they must/may be interpreted.
Specifically, it's not fully clear to me what the IPvX and MAC Address data items [1] are allowed or required to represent for a peer (modem) or a destination (other router). My assumption is that the IPvX are addresses on which the router sends/receives traffic for forwarding on past the DLEP-informed link and the IPvX Attached Subnets are those to-be-forwarded nets, but the MAC Address is really an opaque identifier for the far-side destination and may or may not be an address actually associated with or seen by any of the routers.

In the Link Identifier extension [2] it's more explicitly stated that the MAC Address is supposed to be an address on the far-side router, but I don't see that same kind of language in the original DLEP document [1]. And since there is no signaling of the router MAC Address within the Session Initialization, I assume that it is implied that the MAC Address of the peer (router) used to establish the TCP connection is used for this purpose. For multi-interface routers there may be no relation between the MAC Address and it's routed-traffic IPvX addresses (if the router is talking DLEP on a different interface than the routed traffic), but if the MAC Address is supposed to be just an opaque identifier then this doesn't really matter.

I've been able to dig into the OONF [3] implementation of DLEP to see how it works, but this is just one implementation and not an authority of the correct or possible semantics.

Thanks for any clarification,
Brian S.

[1] https://www.rfc-editor.org/rfc/rfc8175.html
[2] https://www.rfc-editor.org/rfc/rfc8703.html
[3] https://github.com/OLSR/OONF

[manet] DLEP address semantics and in-the-wild ex… Sipos, Brian J.
Re: [manet] DLEP address semantics and in-the-wil… Rick Taylor
Re: [manet] DLEP address semantics and in-the-wil… Henning Rogge
Re: [manet] DLEP address semantics and in-the-wil… Rick Taylor
Re: [manet] DLEP address semantics and in-the-wil… Henning Rogge