Re: [RRG] Assumptions and mapping tools

[David R Oran <oran@cisco.com>]

On Mar 20, 2008, at 11:13 AM, <hannu.flinck@nsn.com> wrote:
> In the RRG proposals we seem to a set of implicit assumptions that I  
> would like get some clarification.
>
> We are assuming that the networks using EIDs are stub networks,  
> networks that do not provide transit and do not peer between each  
> other. Is this really what is needed and required? If this is a  
> valid assumption it should be documented as it is a clear constraint  
> of the applicability.
Not necessarily, only that there is a clear addressing partition  
between the things on the network used for transit and the "AS local"  
address space used to address hosts and other local resources. For  
example, there's no reason why Verizon, or France Telecom, or... could  
not use whatever scheme we decide on to provide independence of  
renumbering of their hosts. Now, the motivation to do that is small,  
since I suspect Verizon would not necessarily want their hosts multi- 
homed with France Telecom, but stranger things have occurred :-)

> ITR/ETR selection (based on weights and priorities) guides the  
> bindings of EID to RLOC which facilitates how the traffic is  
> tunneled (routed and forwarded) over the core.  The ingress and  
> egress devices can be located either at the customer edge or at the  
> provider side. This location impacts whether the originating and  
> receiving sites have access to underlying routing preferences.  
> Should we provide tools to the ingress/egress devices to have  
> visibility to the routing policies affecting how the tunnel is  
> performing?  For instance, should the ingress benefit from knowing  
> the hop counts/costs of certain RLOCs of the egress?
This is, I believe, and open design question, except that I think  
everybody has agreement that injecting routes inbto the global routing  
table to accomplish the TE and/or resilience is not in the solution  
set being considered, since that would put us back where we started  
with respect to routing scalability.
> The location of PTR/proxy matters as they attract traffic and are in  
> charge of forwarding packets causing transit fees. Typically ISPs  
> will forward traffic of their customers routes, and peer supplied  
> routes, but not the traffic of their providers nor between  
> providers. Is this still a valid constraint in the new routing  
> system we are devising? I must assume it is. Consequently the  
> topology and ISP relationships constraint where to place the proxies  
> that are very much needed for the backwards compatibility and  
> incremental deployment.
Yes, I think you've got this right.
> In small case trials how traffic is routed (i.e. the topology and  
> policies) may not really matter much, but in larger ones where the  
> traffic volumes are significant the path selection will matter as  
> their is a cost factor associated to it.
Right, if this didn't matter we'd just do random routing :-)

> Regards
> Hannu


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