The MPLS-OPS Archive

[Robert Raszuk <raszuk@cisco.com>]

Hi Saqib,

I am suprised you say: "an MPLS VPN that supports only (HTTP, ..)". I am
sure you know that mpls-vpn will support = carry any ip unicast packet.

So in your below example I still think that building a separate instance
of routing information - what mpls-vpn exactly provides is not needed.
What I see happening in some provider's networks and also what I would
consider as the optimal desing would be to map all of the overlayed
until now traffic as "special" in the diffserve meaning and carry them
as such in already existing mpls-vpn infrastructure for a given VPN set
of sites. I just don't see any advantage of setting up a special VPN for
carrying such (overlay until now) traffic as you would still need to
apply the identical qos tasks as you would do when you don't have a
separate VPN for it. 

That is all based on what is shipping now in the industry. That is not
to say that at some point of time some vendor may come up with a scheme
to actually setup a guaranteed and assured VPN topology which would
automatically be mapping traffic it carries to a dedicated class in each
router's scheduler packets will be traveling via. But AFAIK nobody is
shipping this today.

R.

> Saqib Jang wrote:
> 
> I think my choice of VoIP (due to the QoS issues surrounding it)
> as an example may have confused the issue. Assuming a number of sites have
> set-up a FR based overlay network to forward a specific type of traffic
> such as HTTP, FTP, or streaming traffic (setting aside the QoS implications
> for now). Does it make sense for them to look to get rid of the overlay
> network and use their existing last mile links thats used for
> all their data traffic in conjunction with an MPLS VPN that supports only
> (HTTP, ..) the specific type of traffic supported by their
> existing FR network. Or will MPLS VPNs not work for such a scenario?
> 
> Saqib
> 
> -----Original Message-----
> From: Robert Raszuk [mailto:raszuk@cisco.com]
> Sent: Monday, March 26, 2001 3:41 PM
> To: saqibj@margallacomm.com
> Cc: mpls-ops@mplsrc.com
> Subject: Re: MPLS/VPN question
> 
> Saqib,
> 
> I don't think that the approach of application specific VPNs even makes
> sense. L2 or L3 VPNs provide you mainly with connectivity (routing
> information distribution).
> 
> For application level scheduling guarantees you should be using the
> right QoS tools available both in each hop as well on ingress. That way
> you can classify very important traffic (VoIP for example) to be taking
> the dedicated LLQ resources at each hop. I don't know how building VPNs
> (routing information disgtribution) may replace basic qos engineering in
> your network.
> 
> Also the existance or not of NMPLS-BGP VPNs is orthogonal to the
> possibiliy of using more complex QoS tools like diffserv aware TE which
> can be a perfect complement to the VPNs itself, but not a reason for it.
> 
> R.
> 
> > Saqib Jang wrote:
> >
> > As I understand it, MPLS/BGP VPNs (per RFC2547) enable site-to-site
> > VPNs at for all traffic flowing between sites in the VPN. Can MPLS
> > VPNs handle the requirement of creation of VPNs among sites for
> > specific types of traffic (say e.g. VoIP traffic)? Would this require
> > a VoIP swtich (other type of allication-aware switches) to be an MPLS edge
> > router or can a "one size fits all" approach work here (i.e. can standard
> > MPLS-aware IP routers create application-specific MPLS VPNs). I'm looking
> > for technical rationale (i.e. not company/product positioning) here.
> >
> > TIA,
> > Saqib
> >
> > Saqib Jang
> > Margalla Communications, Inc.
> > 3301 El Camino Real, Suite 220
> > Atherton, CA 94027
> > Ph: 650 298 8462
> > Fax: 650 851 1613
> >
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