The MPLS-OPS Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] Re: RSVP and LSP questions
Dear Aires, I've written below a few comments to some of the questions you raised. I think that Eric and John have explained most of these, but just to give you my understanding... > 1. Why other type of TE seems not popular (i.e. OSPF TE, etc.)? For me, one of the main dirvers for MPLS-TE is deterministic control of traffic. Particularly in failure cases. With MPLS-TE we have the ability to (i) Use FRR to minimise packet loss in a failure situation by rapidly switching traffic to pre-signalled backup tunnels (ii) Determine exactly where the traffic flows (even in a failure situations) by using efficient routing algorithms to determine the paths for tunnels This enables both connectivity protection and bandwidth guarantees (for high QoS traffic). > 2. What's the behavior of RSVP, when it's configured to constrain & reserved > a 20 MB? Will it maintain 20MB LSP permanently regardless the traffic usage > (no tear down)? This is the typical case. However, John and Eric raise a couple of points to consider (i) Setup and hold priorities for tunnels - If the setup priority of a requested tunnel is higher than the hold priority of an existing (signalled) tunnel, then the existing tunnel can be pre-empted (i.e. torn down). (ii) Autobandwidth - Cisco offers this configurable facility to allow tunnels to be resized periodically to reflect the bandwidth that is actually being used over the tunnel. > 3. If it's not maintained permanently, who's controlling the actual bw > available for the provisioning ? I meant, assuming a total 30MB bw, the > first LSP has been configured with 25MB. Could I create another LSP with > 10MB bw ? It's sort of overbooking ;-) Taking autobandwidth aside, you have control over the bandwidth available for TE, and the physical bandwidth available. By setting these values based on your policies you can determine how you wish to overbook (or underbook) in normal and failure situations. A question I've been asked before is how complex is it to manage the network to deliver the benefits of MPLS-TE? This depends upon the scale of the network. However, I know of at least one management tool that supports the operator in managing all the above criteria and more...;-) ---------------------------------------------------------------------------- -------- Tom Richards Parc Technologies Ltd. 8th Floor The Tower Building 11 York Road London SE1 7NX Tel: +44 (0)20 7261 4002 Mob: +44 (0)7989 854420 www.parc-technologies.com ---------------------------------------------------------------------------- -------- ------- The MPLS-OPS Mailing List Subscribe/Unsubscribe: http://www.mplsrc.com/mplsops.shtml Archive: http://www.mplsrc.com/mpls-ops_archive.shtml |
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