[afnog] Juniper VPLS

ibtisam jamal ibty.jamal at gmail.com
Tue May 14 12:43:48 UTC 2013

Clear now.

On Tue, May 14, 2013 at 12:26 PM, Mark Tinka <mark.tinka at seacom.mu> wrote:

> On Tuesday, May 14, 2013 09:09:55 AM ibtisam jamal wrote:
> > Is there any way that a loop can be caused by just
> > configuring the topology i indicated earlier ?
> The VPLS domain uses a Layer 3 control plane (BGP or LDP) to
> build it. To be thorough, loops are always possible here if
> routing is poorly done, i.e., an IP routing loop.
> As a service, loops are possible at Layer 2, when your
> customers connect to you with switches and decide to
> unintelligently loop them.
> Apart from those two scenarios, I can't see where VPLS would
> cause a loop on its own.
> Personally, I don't like VPLS; I think it's a solution
> looking for a problem. The majority of data networks today
> are IP-based, in which case an l3vpn (which provides an any-
> to-any topology) will be ideal. In most cases where a Layer
> 2 transport has been required, point-to-point or point-to-
> multipoint EoMPLS works much cleaner than VPLS, e.g., old
> ATM machines still running X.25, hotel reservation systems
> still based on IPX, e.t.c.
> Two use-cases where VPLS "can" make sense are when used as
> part of the provider core, and not offered as a service:
>         1. Backhaul for PPPoE-based or DHCP-based broadband
>            services. This replaces the traditional L2TP
>            tunnels that have been used to backhaul broadband
>            connections from customer modems to a BRAS/BNG.
>         2. Mobile backhaul core, as 3G/4G IP networks are
>            typically based on a flat Layer 2 domain so as to
>            support IP mobility across a GSM network.
> If it's not for those two cases, I'd steer clear of VPLS.
> Too much hassle for too little benefit.
> Mark.
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