Masataka Ohta wrote on 22/06/2020 13:49:
But, it should be noted that a single class B routing table entry
"a single class B routing table entry"? Did 1993 just call and ask for
its addressing back? :-)
But, it should be noted that a single class B routing table entry
often serves for an organization with 10000s of users, which is
at least our case here at titech.ac.jp.
It should also be noted that, my concern is scalability in ISP side.
This entire conversation is puzzling: we already have "hierarchical
routing" to a large degree, to the extent that the public DFZ only sees
aggregate routes exported by ASNs. Inside ASNs, there will be internal
aggregation of individual routes (e.g. an ISP DHCP pool), and possibly
multiple levels of aggregation, depending on how this is configured.
Aggregation is usually continued right down to the end-host edge, e.g. a
router might have a /26 assigned on an interface, but the hosts will be
aggregated within this /26.
If you have 1000 PEs, you should be serving for somewhere around 1000
customers.
And, if I understand BGP-MP correctly, all the routing information of
all the customers is flooded by BGP-MP in the ISP.
Well, maybe. Or maybe not. This depend on lots of things.
Then, it should be a lot better to let customer edges encapsulate
L2 or L3 over IP, with which, routing information within customers
is exchanged by customer provided VPN without requiring extra
overhead of maintaining customer local routing information by the
ISP.
If you have 1000 or even 10000s of PEs, injecting simplistic
non-aggregated routing information is unlikely to be an issue. If you
have 1,000,000 PEs, you'll probably need to rethink that position.
If your proposition is that the nature of the internet be changed so
that route disaggregation is prevented, or that addressing policy be
changed so that organisations are exclusively handed out IP address
space by their upstream providers, then this is simple matter of
misunderstanding of how impractical the proposition is: that horse
bolted from the barn 30 years ago; no organisation would accept
exclusive connectivity provided by a single upstream; and today's world
of dense interconnection would be impossible on the terms you suggest.
You may not like that there are lots of entries in the DFZ and many
operators view this as a bit of a drag, but on today's technology, this
can scale to significantly more than what we foresee in the medium-long
term future.
Nick
