RE: Question on draft-ietf-tewg-qos-routing-01.txt

["Ash, Gerald R (Jerry), ALCTA" <gash@att.com>]

Dear James Shen,

Thank you for your interest in the draft.  See below for brief responses.

Regards,
Jerry Ash
AT&T Labs

> -----Original Message-----
> From: shen jing [mailto:jshen@cad.zju.edu.cn]
> Sent: Tuesday, November 06, 2001 7:08 AM
> To: te-wg@ops.ietf.org
> Subject: Question on draft-ietf-tewg-qos-routing-01.txt

> 1. In Annex 2, it is stated EDR shows better performance than FR, TDR &
> SDR, and load state is  preferred to shortest path in  path
> selecting(Annex 2, P13).  But, How multi-path is tried in IP networks? 
> signalling with RSVP-TE or CR-LDP?

Yes multiple LSPs can be signaled with either RSVP-TE or CRLDP.

>  If each connection is set up by this way, will the signalling
>  procedure bring much overhead?

No, especially if flows are routed according to an aggregated 
LSP-bandwidth allocation (denoted as a 'VNET' in the draft).

> If all paths failed, how to deal with the communication request?
> drop or do with best-effort?

Dropped, according to the CAC procedure discussed in the draft. 

> 2. It is stated that Interdomain TE can be built as that in
> intradomain( Annex 2, P13), but there are protocols like BGP
> working in current IP networks which do not maintein any traffic
> state and implements a business-relationship constrained  
> routing method.  Is there any relationship between EDR and 
> BGP in internet?

Not at this time although extensions could be proposed to do so 
or policies could be adopted to mimic EDR.

> 3. In Annex3 P24,  it is stated that bandwidth reservation should be
> included in IP networks,  and per-VNET reservation is recommended,
> but how is VNET defined in a network?

VNET is an aggregate of flows which are routed according to an aggregated 
LSP-bandwidth allocation.  This is analogous to the 'class type' concept 
in the MPLS-DiffServ-TE draft 
http://ietf.org/internet-drafts/draft-ietf-tewg-diff-te-reqts-01.txt.

> 4. In Annex4 P13, it is stated "internetwork E can use various path
> selection methods in delivering connection/bandwidth-allocation
> requests ", the example network give a interconnected networks with 
> different routing methods. But, if it is implemented in this way, 
> should those nodes of internetwork E exchange serval types of 
> routing information?

Yes, the details are spelled out in ANNEX 4 of the draft.

> 5. How do you simulate such a large network ? I means which tools can
> be used to simulate TE & QoS algothrim in a multiservice network?

Service providers with large networks must have the ability to simulate
their networks.  In this case it is an in-house simulation model that is
used.