Subject: RE: [Forces-protocol] Unicast/Multicast/Broadcast and AD stance &use of TCP/SCTP/UDP/IP in ForCES

From: "Putzolu, David" <[email-masked]>
Date: Fri, 19 Mar 2004 08:39:29 -0800

Hi Jamal - response inline.

Jamal wrote >
> huh? DCCP aka UDP with CC built in? We could select
> different CC algos depending on the scope being used.

I think the ADs would be fine with DCCP - but I confess
that I don't know how well DCCP can be used with multicast
transports.

Jamal wrote >
> Is there a draft/RFC which talks transport layer mapping 
> at GSMP level?

Avri is the expert, I'll defer to her :)

Jamal wrote >
> From the outset it does look reasonable. I am assuming that
> the TML serializes the data to the Forces PL?

The abstract TML provides some defined level of service.
I am pretty sure the abstract TML needs to provide a
service where at least one wire that serializes data (don't 
want overlapping add routes or worse ACL entries reordered).  
Whether all TML wires need to be ordered would be up to the 
team to decide - what is the minimum good tranport service 
desired at the ForCES protocol layer?

The TML implementations would need to provide the requested
level of service.  Some might be overachievers, i.e. the
abstract TML might provide guaranteed ordered wires and
wires that do not guarantee ordering.  If the IP TML team
where to decide to use TCP for all wires, then the IP TML
would provide every wire ordered (exceeding the requested
level of service).  The key is every TML implementation
has to at least meet the expected level of service.

-David

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From: Jamal Hadi Salim <[email-masked]>
Date: 19 Mar 2004 20:39:01 -0500

David,

> that I don't know how well DCCP can be used with multicast

My concern was more it sounded evil to be associated with udp.
So i pointed DCCP as something that used that evil UDP.
I know you didnt mean to say that but it sounded like
"if you dont run on top of IP it is ok to use something evil as
that smelly udp". 

We should still be able to use UDP on the local/close proximity scope.
Lets leave this discussion to later.

> want overlapping add routes or worse ACL entries reordered). 

I was more thinking the PL layer doesnt need to know anything about the
wires. It just receives messages from the TML layer which are
serialized. 
It may not be valuable if the PL gets to know all the details
of the transport.
 
> desired at the ForCES protocol layer?

I see the TML-PL interface as local mostly. Maybe TCP if the two reside
on separate nodes.

> has to at least meet the expected level of service.

I think we oughta list all the requirements the differemt TMLs.
reliability, availability, congestion control, security - and then we
need to define the API or the messaging. We may be going a little
overboard.

cheers,
jamal