Re: [Sip] Outbound issues: slides 9 and 10

[Cullen Jennings <fluffy at cisco.com>]

I think we need to work on this proposal before I really understand  
where it is needed and what it protects from. What happens if the  
proxy does not insert a flow token? What proxies are in a foreign  
domain and why do how do they handle things that differently than one  
that is not. This would break some of the proposal for high  
reliability. I think the authors should get together and come up with  
a proposal for what we are talking about here.


On Aug 8, 2006, at 7:38 AM, Rohan Mahy wrote:

> The issues on slide 9 (how does a registrar verify that an edge  
> proxy supports outbound) and slide 10 (what does "Supported:  
> outbound" mean) deal with detecting that all the required hops  
> support outbound.  Slide 9 specifically uncovered a problem with  
> outbound proxies that add a Path URI but don't include a flow token.
>
> The proposed solution is as follows.  If a proxy inserts a Path  
> header with a flow token consistent with the rules described in  
> outbound, it MUST add the ;ob parameter to the proxy URI that has  
> the flow token.
>
> The registrar verifies that any Path header URIs contain the ;ob  
> parameter.  If there are any Path URIs without the ob parameter,  
> the registrar does not return Supported: outbound.  Furthermore,  
> the registrar needs to check that the first hop after the UAC is  
> represented in the Path list (unless the registrar recognizes that  
> the first hop after the UAC is in the same domain and doesn't need  
> to include Path URIs with a flow token).  Note that this implies  
> that whatever the proxy puts in the Via (IP address or FQDN), it  
> must put the same hostname in the Path header (but there is no need  
> for a complete URI comparison).  If the first hop is not correctly  
> represented, the registrar ignores the reg-id parameter and does  
> not return Supported: outbound.
>
> The implication of this is that an outbound-proxy that supports  
> outbound needs to support Path and flow tokens for registrations to  
> all foreign domains.  Inside the same domain, the first-hop proxy  
> and the registrar can still use Path to communicate with each  
> other, but they can use some other private mechanism to  
> disaggregate this functionality.
>
> thanks,
> -rohan
>
>
> _______________________________________________
> Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
> This list is for NEW development of the core SIP Protocol
> Use sip-implementors at cs.columbia.edu for questions on current sip
> Use sipping at ietf.org for new developments on the application of sip

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-implementors at cs.columbia.edu for questions on current sip
Use sipping at ietf.org for new developments on the application of sip