Subject: RE: [NSIS] RMD-QoS-NSLP model draft submitted to NSIS

From: Attila Báder (IJ/ETH)<[email-masked]>
Date: Tue, 17 Feb 2004 16:42:54 +0100

Hi Nary Tra,
 
Thank you for your comments and questions, please find my answers below,
 
Best regards, Attila

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]On Behalf Of Thanh Tra LUU
> Sent: Tuesday, February 17, 2004 2:14 PM
> To: [email-masked]
> Subject: Re: [NSIS] RMD-QoS-NSLP model draft submitted to NSIS
>
>
> hi  Attila,
>
> i've read your draft. i see it as the continuation of rmd model, an one of
> many models that qos-nslp can support. i find it very interesting and i have
> some questions to understand better your model.
>
> 1. How to translate a resource request into resource units request? The
> translation ensures all qos parameters of the original request ?  (e.g.
> delay)

One of the main goals of RMD is to have a very simple resource reservation in interior nodes, therefore all QoS parameters have to be translated into resource units, also delay. This means that reservation may has to be made for peak rate. The number of reource units that has to be reserved for an incoming resoure request depends also on the traffic model used and we see it as an ortogonal problem to the signalling.

> 2. There is a timer for each reservation per flow in interior nodes, so an
> interior node charge will linearly increase following the number of per flow
> sessions?
>

Not exactly, there is not a timer for each flow. In reservation based method we use a sliding window algorithm. The window size is the refresh period and it is divided into N time slots. The window is moved by these time steps. The number of refreshed units and new reservations are counted in each window and the reservation is increased by the difference of these two. Therefore the stored states scales with N.

> 3. In the last paragraph of 2(protocol model), 'they are not able to
> establish and maintain security associations with their neighbors, which
> means, they can only be applied in a trusted domain'. The stateless does not
> mean no security association.  In rsvp, the sa is not specified how it can
> create (maybe by ike, manual) and which node is the next rsvp-aware node.
>

The RMD QoS-NSLP model relies on the (intra-domain) security associations provided by the QoS-NSLP protocol.

> 4. you didn't introduce what TIME_VALUES object is. Just because i'd like to
> know it more clearly.

This is inherited from QoS-NSLP, now I see that it is called REFRESH_PERIOD in the QoS NSLP draft. It is the same as TIME_VALUES of RSVP.

>
> 5. an interior node can be an edge node of other flows ?

No, this was not our purpose. But it is possible to configure an interior node to operate also as an edge node. In that situation additional functionalities have to be included, e.g., when and how the node is used as interior and when as an edge node. 

>
> 6. it seems that an ingress node must know the egress node before making the
> local reservation. Can it be done at the same time ? tell me the reason why
> you don't integrate the e2e reservation and local reservation in a same
> message. I might see the reason in rfc3175, but it's not the answer in your
> case.
>

The main reason is the transport of messages. Most of the RMD QoS NSLP messages 
should be transported in datagram mode, e2e messages usually need reliable transport.

> thanks & regards
> Nary Tra,
> ENST, Paris

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