The MPLS-OPS Archive

["M. ELK" <elkou141061@hotmail.com>]

Hi Steinar

Very nice/useful  summarization for the pro and con .
Aprreciate if U could explain the following :

Quote

Can strongly influence failover times (particularly with traditional 
802.1d).

Unquote

What are the features added to the traditional 802.1d to speed the 
convergence ?? .

My guess that the best way to speed the Spanning Tree is to disable it 
completely as
almost 90% of customers do not have or plan to install  back-door link 
between customer sites .
If back-door link do exist so connect with router .

>From Implementation in U netw , do U enable ST as default ???

Brgds


Brgds


>From: sthaug@nethelp.no
>To: luis-m-a-santos@telecom.pt
>CC: mpls-ops@mplsrc.com
>Subject: RE: [MPLS-OPS]: Question about L2VPN over MPLS
>Date: Tue, 23 Mar 2004 20:31:09 +0100
>
> > What would be the minimum bitrate and what access technology, for
> > which it would make economic sense to deploy VPLS?  (as opposed to,
> > for instance, having more "traditional" L3 VPNs such as BGP/MPLS or
> > Virtual Router)
>
>I'm still not sure that's the right question. L2 VPNs (VPLS) and L3
>VPNs (MPLS/RFC 2547 or similar) serve different purposes. Both are
>point to multipoint technologies, so they can basically handle much
>the same topologies.
>
>L3VPNs:
>- Have no issues with MAC learning, spanning tree protocol and similar.
>- Nice if you want the ISP do to routing for you.
>- You need to worry about routing protocol redistribution between BGP
>(ISP) and customer routing protocols. Can strongly influence failover
>times.
>- More mature technology than L2VPNs.
>- IP only.
>
>L2VPNs:
>- You need to worry about MAC learning, spanning tree protocol and
>similar. Can strongly influence failover times (particularly with
>traditional 802.1d).
>- Nice if you want to do the routing yourself.
>- No issues with routing protocol redistribution.
>- Newer technology than L3VPNs, less equipment/fewer vendors that
>support it.
>- Protocol independent.
>
>In some ways L2VPNs are "simpler" - but in reality this is only the
>case if you're familiar with L2 networks and their issues.
>
>Yes, there are time-sensitive L2 protocols (e.g. LAT, various IBM
>protocols) that may need a higher bandwidth (say more than 256 kbps)
>to work well over an L2 cloud. However, I would probably worry less
>about that than the other points in the lists above - remember that
>people have been running L2 protocols over low-speed FR links for
>many years.
>
>Steinar Haug, Nethelp consulting, sthaug@nethelp.no
>
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