The MPLS-OPS Archive

[Robert Raszuk <raszuk@cisco.com>]

Mathew,

Sorry but couldn't resist :) ..

You said ...

> RFC2547 is good 
> for large, complex VPNs, but too complicated for smaller VPNs or 
> point-to-point. Note that "simple" or "complex" refers to the end 
> customer's view of the service.

> So, while I agree that IP routing over L3 VPNs could be easier,

Pls notice that 2547 does not require ANY ACTION on the end customer
site to connect his sites. In fact it transparently provides a
"multihop" IGP result - something what Daniel was looking for. How it
can get more simple ???

I understand his concern that some of enterprise IT departments may be
actually IP aware and would like to run their own network - for those
CSC for me seems better. L2VPNs especially IP oriented L2VPNs (something
which will be comming in couple of months - watch IETF space ;) are also
usefull. TLS IMHO should be limited to MANs only. 
And there is no single statement that one or this is better. I just
don't want to allow spreading not correct statement about one or the
other of those VPN technics :).

R.


> Mathew Lodge wrote:
> 
> At 03:24 PM 1/23/2002 -0800, Daniel Kharitonov wrote:
> >L2 VPNs are a good solution to one problem and a bad
> >solution to another. Specificly, "fixing" the need for
> >the usable L3 VPNs w/L2 VPNs is a bad trend.
> >First, L2 VPN needs n^2/2 tunnels to be configured for
> >n customer endpoints. Next, hauling full L2 (read,
> >Ethernet) traffic is unnecessary and also brings the
> >MTU problem on the table. You will be very surprised
> >to know, how many brand-name routers and switches are
> >simply incapable of taking ethernet packets larger
> >than 1536 bytes.
> 
> >In a word, I am a strong advocate for the L3 VPNs
> >without client's routing tables propagated through
> >ISP.
> 
> To me, the L2/L3 MPLS discussion is like the "switching vs. routing"
> argument of some years ago. The answer was, of course, "both"... but that
> never makes for a good headline :-)
> 
> Specifically, Martini is great for simple point-to-point L2 (a service
> concept that has been selling very well for years in the guises of private
> line, frame relay PVCs and ATM PVCs), and Lasserre-Kompella is great for
> small, simple VPNs (where the n^2 mesh is not an issue). RFC2547 is good
> for large, complex VPNs, but too complicated for smaller VPNs or
> point-to-point. Note that "simple" or "complex" refers to the end
> customer's view of the service. The interesting thing is that these
> technology solutions seem to map fairly well to small, medium and large
> enterprises, respectively, so there's a sort of "natural" segmentation of
> the marketplace.
> 
> As far as MTU issues, many switching vendors are requiring a new MPLS card
> or a switch/router card upgrade to get MPLS capability, and are taking the
> opportunity to fix any MTU problems with that upgrade. A limited set of
> card upgrades seems palatable to the SPs that I've talked to.
> 
> So, while I agree that IP routing over L3 VPNs could be easier, I believe
> that there are going to be several different L2 and L3 MPLS services that
> will appeal to different segments of the end customer marketplace. This
> would be a path of lower resistance for a service provider rather than
> requiring end customers to adopt a new "multihop aware" routing protocol.
> 
> Cheers,
> 
> Mathew
> 
> | Mathew Lodge                 | mathew@cplane.com     |
> | Director, Product Management | Ph: +1 408 789 4068   |
> | CPLANE, Inc.                 | http://www.cplane.com |
> 
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