reachability issue with 3ffe:80a::/32 (PAIX IX segment)

[Stephen Stuart]

>    	i can think of couple of solutions:
>    	- an IX (say PAIX) gets an sTLA/pTLA.  the IX announces it to the world
>    	  based on normal prefix length (like /28 for pTLA).  the IX will
>    	  ensure connectivity between IX segments (so there will be no
>    	  reachability issue).
>
> => this seems the good solution (IXes are good TLA candidates!)

How does an entity that does not operate a router announce any kind of
prefix to the world?

Networks that attach to an IX need to carry the /64 of the IX network
in their IGP or iBGP in order to recursively look up next-hop
addresses of peers at that IX. 

The only thing that having the IX announce an aggregated prefix would
accomplish is to allow traceroute for networks *not* connected to the
IX to work without seeing "* * *" in place of the hop through the
IX. While it's nice when traceroute works, traffic will flow correctly
on a path without it.

As I said in my previous mail, PAIX does *not* operate a router, and
does *not* compete with its customers for the wide-area carriage of
traffic.

One of the problems we encounter at IXes is participants who rewrite
next-hop or install static routes to cause other networks to carry
traffic that they did not offer to carry. This same technique could be
used to cause an IX that offered interior connectivity between
exchange points to function as a transit carrier. An IX that does not
want to function as a transit carrier now has to implement defenses
against it; an IX that does now competes with its customers. Neither
option sounds good to me.

Stephen
 --
Stephen Stuart					stuart@mfnx.net
VP, Research and Advanced Development
Metromedia Fiber Network

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