V4 via V6 and IGP routing protocols

Mon Apr 4 14:24:31 UTC 2022

Mark Tinka wrote:

>> MPLS with nested labels, which is claimed to scale because
>> nesting represents route hierarchy, just does not scale because
>> source hosts are required to provide nested labels, which
>> means the source hosts have the current most routing table at
>> destinations, which requires flat routing without hierarchy or on
>> demand, that is, flow driven, look up of detailed routing tables
>> of destinations at a distance.
> 
> This detail is limited to PE devices (ingress/egress).

As it requires

 >> flat routing without hierarchy or on
 >> demand, that is, flow driven, look up of detailed routing tables
 >> of destinations at a distance.

MPLS is just broken.

> You don't need to 
> carry a BGP table in the P devices (core), as only label swapping is 
> required.

So?

> Fair point, it is a little heavy for an edge box,

Requiring

 >> flat routing without hierarchy

means it is fatally heavy for intermediate boxes.

 >> or on
 >> demand, that is, flow driven, look up of detailed routing tables
 >> of destinations at a distance.

means it is fatally heavy for edge boxes.

 > In the end, having a flat L2 domain was just simpler.

That's totally against the CATENET model. Why, do you think,
NHRP was abandoned?

 > we've never ran into an issue carrying
 > thousands of IS-IS IPv4/IPv6 routes this way.

Thousands of? Today with so powerful CPUs, that is a small
network. So?

						Masataka Ohta