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RE: [RPRWG] A problem with fairness messages





John,

Thanks for pointing that out.  When I thought of
the issue, I missed the part that TTL stripping 
would take care of it.

-Anoop

> -----Original Message-----
> From: John Lemon [mailto:JLemon@xxxxxxxxxxxx]
> Sent: Thursday, June 13, 2002 5:15 PM
> To: 'Anoop Ghanwani'; 'stds-802-17@xxxxxxxx'
> Subject: RE: [RPRWG] A problem with fairness messages
> 
> 
> Anoop,
> 
> The other key difference is that Type A messages have a TTL 
> of 1, whereas
> Type B messages have a TTL of 255. Therefore, Type A messages will be
> stripped based on TTL value, whereas Type B messages will be source
> stripped.
> 
> jl
> 
> -----Original Message-----
> From: Anoop Ghanwani [mailto:anoop@xxxxxxxxxxxxxx]
> Sent: Thursday, June 13, 2002 4:49 PM
> To: 'stds-802-17@xxxxxxxx'
> Subject: [RPRWG] A problem with fairness messages
> 
> 
> 
> 
> In the current version of the draft, we have:
> - Type A fairness messages that are propagated 
>   hop-by-hop; and
> - Type B fairness messages that are broadcast.
> 
> However, fairness messages do not contain 
> a destination address, and the only thing that 
> identifies them as fairness messages is the 
> 2-bit "Packet Type" value in the ring control
> field.  This doesn't tell us whether the message 
> is Type A or Type B; that is done by the fairness 
> control header which is interpreted in the FCU.
> 
> This means that both Type A and Type B messages
> must essentially be "dropped" (i.e. stripped)
> from the ring and passed to the fairness control 
> unit (FCU).  The FCU then discovers that the frame 
> is a Type B message and "adds" it back to the ring.
> This is not broadcast behavior from the standpoint 
> of the RPR MAC.
> 
> There are two possible solutions for this problem:
> 1 - Introduce a destination MAC address in fairness
>     messages; or
> 2 - Use two separate "Packet Type" values --
>     one to indicate a Type A fairness message and 
>     one to indicate Type B fairness message.
> 
> I personally prefer #1 and was going to put in
> a comment with respect to that, but I thought I'd
> share this with the list to see what others feel.
> 
> -Anoop
> --
> Anoop Ghanwani - Lantern Communications - 408-521-6707
>