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

[Vishwas Manral <[e-mail]>]

Resending as DWards Cisco address was used.

Thanks,
Vishwas

On Sun, Apr 4, 2010 at 8:32 PM, Vishwas Manral <[e-mail]> 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
>