Point to Point Ethernet

Zartash Uzmi zartash at gmail.com
Thu Jul 9 20:33:10 UTC 2009


This may be partial hijack of the thread or even a trivial query but I ask
this since you mentioned "For cost reasons, Ethernet is often used". We hear
this argument all the time. The standard unabridged reason I have learned is
the ubiquity of Ethernet devices, whatever that means. Can you say why
precisely the cost of Ethernet is low compared to other viable alternatives?


On Thu, Jul 9, 2009 at 7:29 PM, Cayle Spandon <cayle.spandon at gmail.com>wrote:

> I frequently run into scenarios where two devices (two routers, or a
> router and a host) need a point-to-point connection to each other with
> a capacity of (much) more than 10 Gbps.
> For cost reasons, Ethernet is often used.
> Since more than 10 Gbps is needed, we end up with multiple parallel
> 10GE point-to-point connections.
> Because the devices often don't support LAG or have limitations on the
> number of links in a LAG, we often cannot use LAG at all or cannot put
> all 10GE links in a single LAG group.
> So, we end up with multiple parallel layer-3 point-to-point
> connections where each connections is either an Ethernet or a LAG
> group.
> Furthermore, in order to conserve IP addresses, there is a desire to
> make these interfaces unnumbered.
> The involved devices have a numbered loopback interface whose address
> is used as the "donor" for the unnumbered Ethernet / LAG interfaces.
> Most router vendors already support unnumbered point-to-point
> Ethernet, see for example:
> http://www.juniper.net/techpubs/en_US/junos9.5/information-products/topic-collections/config-guide-network-interfaces/interfaces-configuring-an-unnumbered-interface.html#id-10432956
> However, there are some interoperability issues / open questions
> related to point-to-point unnumbered Ethernet, see for example:
> http://forums.juniper.net/jnet/board/message?board.id=JUNOS&message.id=130
> http://forums.juniper.net/jnet/board/message?board.id=switch&thread.id=835
> I would be very interested in some standards (i.e. an IETF BCP) to
> describe the best current practices for these applications of
> Ethernet.
> I am not particularly interested in re-inventing a new flavor of
> Ethernet for this application. All that is needed, in my opinion, is
> some clarifications or best practices on how to use the existing
> standards to create point-to-point unnumbered Ethernet connections.
> PS -- I am also aware of some esoteric BRAS applications of Ethernet
> where one side is numbered and the other side is unnumbered.

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