The MPLS-OPS Archive

["Saurabh Srivastava" <saurabhs@nortelnetworks.com>]

Title: Message

I agree the Best of both worlds is a hybrid approach.

 

-Offline - Periodically to globally optimize network and pre-calculate backups for failure scenarios.

-Online CSPF - Fine tune between offline calculations.

 

Saurabh

-----Original Message-----
From: Tom Richards [mailto:tom.richards@parc-technologies.com]
Sent: Wednesday, March 12, 2003 1:46 PM
To: 'Lavoisier José Leite Farias'; Sandmaier, Jan; ILazar@burtongroup.com; mpls-ops@mplsrc.com
Subject: RE: [MPLS-OPS]: On-line TE?

 

Two key drivers for TE are

1) B/W optimisation

2) Protection against failures

 

In my view, to say that on-line is better for addressing faults is not quite right.  Off-line can be used to generate FRR backup tunnels a priori that address fault situations (as in Cisco's Tunnel Builder Pro).

 

My view is that a hybrid of the two approaches seems to be a sensible structure.  On-line TE can be used

1) As a fall-back where off-line pre-calculated (pre-configured) paths/tunnels have failed.

2) As a rapid response to route traffic

While off-line optimises globally and pre-calculates backup tunnels/paths for failure situations.

 

Tom

-----Original Message-----
From: Lavoisier José Leite Farias [mailto:lfarias@cpqd.com.br]
Sent: 12 March 2003 16:59
To: Sandmaier, Jan; ILazar@burtongroup.com; mpls-ops@mplsrc.com
Subject: RES: [MPLS-OPS]: On-line TE?

Is there any advantage by choosing one or other option ? I understood by reading Irwin's answer that on-line TE is used as fault mechanism.

I believe off-line calculation it seems to keep the whole network optimized. am I correct ?

 

Regards,

Lavoisier.

-----Mensagem original-----
De: Sandmaier, Jan [mailto:Jan.Sandmaier@t-systems.com]
Enviada em: quarta-feira, 12 de março de 2003 11:44
Para: ILazar@burtongroup.com; mpls-ops@mplsrc.com
Assunto: AW: [MPLS-OPS]: On-line TE?

Irwin,

 

the two concepts are not so different. In off-line TE you collect traffic rates from all your LSPs in the network, feed the traffic matrix in an optimization engine which produces explicite routes which are used by a provisioning tool to build up the new paths. It is up to the oparator when he adjusts the model or which triggers are used for ajustment. Engineered paths are also adjusted accordingly based on actual network conditions as with on-line TE. You may use on-line TE/dynamic LSPs as a fallback mechanism in case of a link outage. The triggers in on-line TE are configured thresholds and reoptimization timers so there is no big difference. The difference is more centralized computation versus distributed.

 

Jan

-----Ursprüngliche Nachricht-----
Von: Irwin Lazar [mailto:ILazar@burtongroup.com]
Gesendet: Freitag, 7. März 2003 16:32
An: mpls-ops@mplsrc.com
Betreff: [MPLS-OPS]: On-line TE?

I've seen quite a few vendorst that offer sophisticated systems for off-line TE.  My understanding is that this is done by downloading sample network data into a TE optimization engine?  Correct?

 

Is there anyone out there doing on-line TE - in which real-time network traffic is processed and engineered paths are adjusted accordingly based on actual network conditions?

 

Thanks,

Irwin