Subject: [NSIS] GIST: Is Loose-End MRM REQUIRED?

From: Christian Dickmann <[email-masked]>
Date: Sat, 10 Mar 2007 19:21:26 -0500

Hi Robert,

I noticed that TCP and TLS over TCP are REQUIRED in the RFC 2119 sense. 
In addition, for the PC-MRM the downstream encapsulation is REQUIRED, 
while upstream encapsulation is OPTIONAL (for the sending part).  
However,  the MRMs themselves have no text stating that they are 
REQUIRED. I would assume that support for PC-MRM is REQUIRED, while 
support for LE-MRM is OPTIONAL, because there might be special GIST 
implementations just meant to work with QoS NSLP which do not need 
LE-MRM to work.

Regards,
Christian Dickmann

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From: "Hancock, Robert" <[email-masked]>
Date: Mon, 12 Mar 2007 14:19:58 -0000

hi, 

> -----Original Message-----
> From: Christian Dickmann [mailto:[email-masked]] 
> Sent: 11 March 2007 00:21
> To: [email-masked]
> Subject: [NSIS] GIST: Is Loose-End MRM REQUIRED?
> 
> Hi Robert,
> 
> In addition, for the PC-MRM the downstream encapsulation is 
> REQUIRED, while upstream encapsulation is OPTIONAL (for the 
> sending part).  
> However,  the MRMs themselves have no text stating that they 
> are REQUIRED. I would assume that support for PC-MRM is 
> REQUIRED, while support for LE-MRM is OPTIONAL, because there 
> might be special GIST implementations just meant to work with 
> QoS NSLP which do not need LE-MRM to work.

here, the underlying point is that the MRMs required strictly 
depend on the NSLPs to be supported. so if you have an NSLP which
only uses MRM foo (still to be specified), there is no particular
need for a node which only hosts foo to have a GIST implementation
which support PC-MRM or LE-MRM. that is why the specification leaves
the 2119 status of the MRMs open.

OTOH, there is also case that it is good to have MRMs supported
because otherwise it becomes a deployment drag for new applications
(you have to go and check every implementation and find out whether
it supports the MRMs that you need, which is a pain). So, even though
the MRMs are not logically required, it is still good for the
specification
to send a message that you would be silly not to implement them.

it would be interesting to know other people's views on this. on
balance, there is a good case for saying that both MRMs are SHOULDs.
i would even say MUST, except for the fact that the PC-MRM is
actually probably the hardest part of the protocol to implement
correctly, so making it an unavoidable part of the protocol seems
like too much cost for future NSIS applications which don't need
it.

cheers,

robert h.

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From: Martin Stiemerling <[email-masked]>
Date: Wed, 14 Mar 2007 15:15:14 +0100

> balance, there is a good case for saying that both MRMs are SHOULDs.

It would go for SHOULD as RFC 2119 says for this case:
"to ignore a particular item, but the full implications must be  
understood and    carefully weighed before choosing a different course.

   Martin

> like too much cost for future NSIS applications which don't need

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