Re: [Sip] draft-ietf-sip-rph-new-namespaces

[Janet P Gunn <jgunn6 at csc.com>]

In line


Henning Schulzrinne <hgs at cs.columbia.edu> wrote
on 10/25/2007 11:01:40 PM:

> Keith asked me to review the draft; here are a few quick comments:
  
> Why priority values that are even only?

Priority values are completely arbitrary.  If
you wanted to, you could have priority values

YP17
42
-Pi
i
e


> 
> The wording is somewhat redundant, with the same information repeated
 
> three times, but in slightly different ways. In particular, the  
> notion of non-preemption across namespaces seems to be couched in
 
> caveats. It seems that preemption across namespaces is sometimes  
> permitted and sometimes not, which makes it rather difficult to build
 
> an implementation for the namespace without either a lot of  
> configuration options or special software versions for each policy.
 
> We have seen in other areas that excessive configurability leads to
 
> interoperability problems and code complexity. I have a hard time
 
> picturing how to build such a configurable system without a monster
 
> language and all kinds of strange interactions. What happens if  
> namespace 30 can preempt namespace 28, and vice versa? What about
 
> circular preemption chains (30 -> 17 -> 10)? In those cases,
do  
> namespaces have absolute priority, i.e., any priority in 30 beats
any  
> priority in 28? You'd have to create a matrix with 250 by 250 entries
>

I guess I am reading it somewhat differently
from you.

I read nothing that suggests that one namespace (as
a whole)can preempt another namespace.  In fact that is explicitly
forbidden.

What is discussed as a possibility (consistent with
RFC 4412)is making two or more namespaces "equivalent".  
For instance, if you make dsn-000001 and dsn-00000A "equivalent"
then dsn-000001.0 and dsn-00000A.0 would be completely equal in priority.


Similarly dsn-000001.8 and dsn-00000A.8 would be completely
equivalent in  priority.

In this case dsn-000001.0 could neither preempt, not
be preempted by, dsn-00000A.0.  But dsn-000001.0 could be preempted
by EITHER dsn-000001.8 OR by dsn-00000A.8.

And dsn-000001.8  neither preempt, not be preempted
by, dsn-00000A.8.  But dsn-000001.8 could preempt EITHER dsn-000001.0
OR dsn-00000A.0

Janet

> 
> 
> Henning
> 
> 
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