Re: WG next steps

[Eliot Lear <lear@cisco.com>]

Ohta-san,

One could argue this from an academic point of view, and I could also 
argue that it holds true in certain high end configurations, but forcing 
end hosts to participate in the IGP is in general a bad idea for certain 
practical reason:

OSPF requires that nodes not filter the database.  It does this so that 
no matter how a node receives the database it will be consistent, the 
goal being quick convergence.  Realistically an enterprise administrator 
cannot allow the potential for meddling that an end host can cause, say, 
by declaring itself an ABR to a new area 0.

OSPF itself (nor any other routing protocol I know today) provides no 
object level security, and so all updates must be taken at face value 
from authenticated sources.  The impact on distance vector protocols is 
less because you can filter, but there are other problems withn DV (or 
for that matter PV).

In addition, any requirement to change the paramaters of the routing 
system would require that those changes be propagated not just to the 
routers but all the way to every end host systems, causing a system 
administration nightmare in large systems.  In particular, any change of 
timing parameters or area assignment would prove difficult.  One of the 
 commonly preferred IGPs doesn't even use IP, requiring all sorts of 
additional configuration.

The general case, therefore, is that end systems will NOT participate in 
a routing system.  Now, perhaps they would use some sort of request 
response protocol to retrieve routing direction, but that should be the 
extent of it, and it's still not clear that's a good idea.

A reasonable question to ask is whether the IGP/EGP split is the correct 
one these days, as lots of policy is lost in the conversion.

Eliot

Masataka Ohta wrote:
> Michael;
>
>
> > > No. The mechanism is already there and called routing protocols.
> > Why does this not imply that each host in a multi-homed site would have to 
> > participate in the site's IGP?
>
> The end to end principle implies that each host should have
> all the information and should receive IGP.
>
> Routers are still allowed to convert format of IGPs for hosts
> not to be able to understand new ones.
>
> 							Masataka Ohta