Requirements Defintion

[Jim.Bound@nokia.com]

Using Itojuns list to get started lets work on what the requirements are
which needs to be done before any good engineering project.
I have added some additional words to Itojuns categories.  If we can get the
requirements defined we can then build a charter and have some concrete
focus for work at Minneapolis meeting.  I then add other reqs after Itojun's
mail.

Be good to work on these and move forward.  The order of the list can be
done later.

1.  Define who are the principles affected by Multihoming.
This should include also Edge, Border, and Intermediate Routers and affect
to clients.
> who are you?
> - a SLA, or a leaf site (/48)
> - an NLA, or small ISP (/n, where n < 48)
> - a TLA, or big ISP (/16, /29-35 sTLA, or /24-28 pTLA)
> 

Define the problems caused by multihoming and the ones we want to address
and the goals of us addressing those problems.  What is our output in the
IETF.
> goals of multihoming
> - cope with L2 failures
> - cope with upstream ISP failures
> - load balancing, try to fill up two pipes we have toward upstream
> 	this needs more routing tricks.
> - whatever you name it (but shouldn't dream too much, we need 
> a workable
>   operational solution not a 20-year-to-deploy new protocol)
> 

Define prefix aggregation problems and solicit technical solutions, look at
existing
solutions and warts/holes in those solutions.  
> backbone aggregation and routing table size
> - RFC2373 and RFC2772 are pretty clear (for me) about 
> aggregation is required
>   when TLA/pTLA/sTLA site propagates their TLA/pTLA/sTLA to 
> the backbone (DFZ).
>   do we want to keep this property (pros: less specific 
> routes  cons: no
>   provider-independent, or TLA-independent address), or do we 
> want to forget
>   about it (pros: IPv4-like "i have provide-independent 
> address and advertise
>   it to both ISP" multihome possible  cons: more specific routes)
> - what is the permissible maximum # of IPv6 routes in DFZ?  
> what is the
>   limiting factor? (memory bound, CPU bound)  how can we 
> enforce the max #?
>

Define how multihoming can be and could be used.  What are the actual
mechanisms to be analyzed to provide solutions for short term and long term.

> for a SLA (/48 leaf site), multihome can be:
> - connect to the same upstream ISP with multiple links
> - connect to different ISPs with multiple links.  it has two 
> axis (not very
>   independent, and there's relationship with backbone aggregation):
>   (1) ISP A and B belong to the same aggregated address block 
> (like the same
>       TLA).
>   (2) ISP A and B belong to different aggregated address 
> block (like the
>       different TLAs).
>   (a) SLA gets single /48 prefix from one of the upstreams 
> (ISP A).  advertise
>       it to both ISP A and B -> how far they will get propagated?
>   (b) SLA gets two /48 prefixes from both of the upstreams 
> (ISP A and B).
>       advertise prefix A to ISP A only, advertise prefix B to 
> ISP B only.
>

Whats the effect of those solutions downstream. 
> for an NLA?
> for a SLA which is connected to multihomed NLA?
> for a TLA?
> - TBD
>

Define tools to assist with multihoming and tools if things change. 
> tools in our hand:
> - DNS
> - RFC2260-like configuration (tunnel, redundant L2 connectivity)
> - multiple address assignment to a site
> - source address selection logic at the end node
> 	note: unlike IPv4, every IPv6 node can handle multiple 
> IP address
> 	assigned to a single interface.
> - GSE-like mechanism?
> - router renumbering protocol
> - IPv6 autoconfiguration, including "deprecated" address handling
> 

What are the protocol issues from multihoming.
> other issues:
> - what happens to established TCP sesssions when ?
> - how an endpoint measure which address is better and which is worse?
>   (need global routing knowledge, or keep monitoring different paths)
>

What are the implementation effects to IPv6 as implemented today given
various solutions.

Can Internet Exchanges play a role in reducing routing table size for prefix
aggregation.

What are the security ramifications.

What are the network performance ramifications and what is needed.

others.................

/jim