Re: [mpls-tp] draft-boutros-mpls-tp-performance

[Stewart Bryant <[e-mail]>]

Vishwas

Thank you for reviewing draft-boutros-mpls-tp-performance

 http://tools.ietf.org/html/draft-frost-mpls-tp-loss-delay-00 is a more 
robust protocol for measuring loss/delay and is the draft that I would 
prefer to move forward with.

- Stewart


Vishwas Manral wrote:
> Hi,
>
> I noticed some interesting things in the performance monitoring draft.
> The most interesting thing is point 4 I have noted.
>
> 1. The draft may be trying to measure packet loss but it assumes the
> performance messages cannot be lost. This seems like a very
> interesting assmption.
>
> 2. On the same lines if we assume the above not true, we may need to
> define retransmits from senders and no/ ACK NACK retransmits.
>
> 3. We also need to define how to identify duplicate messages and how
> duplicate packets are to be treated.
>
> 4. I also notice to measure packet loss we use the sequence number in
> the packets themselves:
>
> To measure packet loss I guess the receiver looks at the gaps in the
> sequence numbers. However there are basic issues with this.
>
> Sender sends packet 1 to 100. Receiver receives packet 1 to 80.
> Receiver does not know 100 packets are going to be sent, so it says
> packet loss is 0 even though there are 20 packets that are lost.
>
> 5. I assume it would be good to state that the sequence number of the
> first packet is 1. Also if there are wrap arounds what needs to be
> done. In my view we should use 64 bit values for sequence numbers, it
> is like a packet counter.
>
> Thanks,
> Vishwas
>
>   


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