[c-nsp] ipv4 link-local for eigrp

[Adam Armstrong]

Alexander Clouter wrote:
> Hi,
>
>
> The biggest issue is all the rfc1918 usage used in the /30 used to force 
> the L3 routes out to the edge of the network which make traceroutes 
> ugly.  I really do not want to put aside publicly routable addresses 
> that are just used to pass EIGRP data around, as that would involve 
> soaking up over 50 /30's, a bit of a waste.
>
> So what to use, I am pretty keen to use link-local IPv4 addresses 
> (169.254.0.0/16) much like I plan to for IPv6 to build up the L3 
> point-to-point links and they are perfect for this situation.  The 
> downside is that I run into the following issues:
>  1. 169.254.0.0/16 can start to appear in the distributed EIGRP listings
>  2. traceroutes have 169.254.0.0/16 addresses in them
>  3. 169.254.0.0/16 is pingable by edge hosts as the switch they are
>         plugged into knows of at least one 169.254.0.0/16 address.
> 	These addresses should never escape the local subnet
>   
Using rfc addressing space for links that internet traffic traverse is a 
little bit filthy, imo. It makes a mess of traceroute and potentially 
sources traffic onto the internet from those addresses (which, 
hopefully, is subsequently dropped by filters/urpf).

If you're really worried about an wasting a couple of addresses, switch 
all of your links to /31s and bask in the knowledge that you've done 
more than most.

We've just migrated all of our linknets from 10/8 space to publicly 
addressable space, partly because i believe "it's the right thing to do" 
and partly because it irritated customers.

IMO, using RFC space gives you no benefits, other than having saved a 
few addresses (it does not give *you* more addresses, it saves teh world 
some addresses). It does, however, have a number of drawbacks.

adam.