nanog mailing list archives
Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?)
From: Nick Hilliard <nick () foobar org>
Date: Mon, 22 Jun 2020 14:55:33 +0100
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 theISP.
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
Current thread:
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?), (continued)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Mark Tinka (Jun 21)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Masataka Ohta (Jun 21)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Mark Tinka (Jun 21)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Masataka Ohta (Jun 21)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Robert Raszuk (Jun 21)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Masataka Ohta (Jun 22)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Mark Tinka (Jun 22)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Masataka Ohta (Jun 23)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Owen DeLong (Jun 23)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Masataka Ohta (Jun 24)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Nick Hilliard (Jun 22)
- RE: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) adamv0025 (Jun 22)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Mark Tinka (Jun 22)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Masataka Ohta (Jun 23)
- BGP flooding Robert Raszuk (Jun 23)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Mark Tinka (Jun 21)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Masataka Ohta (Jun 22)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Mark Tinka (Jun 22)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Randy Bush (Jun 22)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Fletcher Kittredge (Jun 23)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Masataka Ohta (Jun 23)