The MPLS-OPS Archive

[Mathew Lodge <mathew@cplane.com>]

At 04:54 PM 7/9/2002 +1200, Simeon Pilgrim wrote:
>He means where you use static LSP's that have been
>generated/calculated via some offline method.
>
>By offline this means some system that is not part of the routing
>system. ie some network management software running on a PC or
>mainframe.

Right -- you use management software to compute the optimal primary and 
backup LSPs on a server somewhere, and then install them on the MPLS 
network using RSVP-TE explicit routes (or equivalent). The main advantages 
are the level of control you gain, and the predictability of the resulting 
MPLS network.

In addition to Chris Liljenstolpe's draft, there is a CPLANE white paper on 
this approach to TE at

http://www.cplane.com/technologies/tech_register.asp


Thanks,

Mathew



>  There was a good draft rfc "draft-liljenstolpe-tewg-cwbcp-01.txt"
>that was from a Cable & Wireless person, that had a very good reasons
>to do this. Not sure if the draft is still around as it expired june
>2002. If it can't be found I can mail interested parties a copy.
>
>
> > Mathew, would you go into a bit more detail on what you mean by "off-
> > line traffic engineering"? If you reference has me stumped, I'll bet
> > there are others out there with the same question.
> >
> > Thanks much.
> >
> > Roger Williams
> >
> > At 06:25 PM 7/8/2002, you wrote:
> > At 08:25 AM 7/5/2002 -0500, Christopher Lewis wrote:
> > Plain MPLS or MPLS VPN will work fine with distance vector protocols
> > like EIGRP, but as mentioned a link state routing protocol is needed
> > for MPLS traffic engineering, as each node needs the topology
> > information those protocols provide and OSPF and IS-IS have the
> > opaque LSA extensions necessary for traffic engineering.
> >
> > To add to Chris' comments, note that this is for online "on the
> > router" traffic engineering only. If you're doing off-line traffic
> > engineering, any routing protocol that allows the control plane to
> > operate will do.
> >
> > Three benefits that offline TE offers vs. OSPF/IS-IS TE:
> > 1) You can implement a routing algorithm that does a lot better than
> > Dijkstra shortest path. For example, you can minimize overall network
> > utilization and avoid bottlenecks.
> > 2) You can pre-calculate and install backup LSPs and ensure that
> > there are no single points of failure, thereby dramatically improving
> > LSP restoration time and guaranteeing resiliency.
> > 3) You can support LSP constraints that are non-additive in nature --
> > since shortest path works by adding hop metrics.
> >
> > Cheers,
> >
> > Mathew
> >
> > -------------------------------------------------------------------------
>Simeon Pilgrim                      27 Nazareth Avenue
>Software Engineer                  PO Box 8011
>Allied Telesyn Research         Christchurch 8034
>phone: +64 3 339 3000            New Zealand
>fax:      +64 3 339 3001
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| Mathew Lodge                 | mathew@cplane.com     |
| Director, Product Management | Ph: +1 408 789 4068   |
| CPLANE, Inc.                 | http://www.cplane.com | 

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