nanog mailing list archives
Re: Devil's Advocate - Segment Routing, Why?
From: Masataka Ohta <mohta () necom830 hpcl titech ac jp>
Date: Fri, 19 Jun 2020 23:45:23 +0900
Mark Tinka wrote:
MPLS has been around far too long, and if you post web site content still talking about it or show up at conferences still talking about it, you fear that you can't sell more boxes and line cards on the back of "just" broadening carriage pipes.
The problem of MPLS, or label switching in general, is that, though it was advertised to be topology driven to scale better than flow driven, it is actually flow driven with poor scalability. Thus, it is impossible to deploy any technology scalably over MPLS. MPLS was considered to scale, because it supports nested labels corresponding to hierarchical, thus, scalable, routing table. However, to assign nested labels at the source, the source must know hierarchical routing table at the destination, even though the source only knows hierarchical routing table at the source itself. So, the routing table must be flat, which dose not scale, or the source must detect flows to somehow request hierarchical destination routing table on demand, which means MPLS is flow driven. People, including some data center people, avoiding MPLS, know network scalability better than those deploying MPLS. It is true that some performance improvement is possible with label switching by flow driven ways, if flows are manually detected. But, it means extra label-switching-capable equipment and administrative effort to detect flows, neither of which do not scale and cost a lot. It cost a lot less to have more plain IP routers than insisting on having a little fewer MPLS routers. Masataka Ohta
Current thread:
- RE: Devil's Advocate - Segment Routing, Why?, (continued)
- RE: Devil's Advocate - Segment Routing, Why? adamv0025 (Jun 19)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 19)
- Re: Devil's Advocate - Segment Routing, Why? Radu-Adrian Feurdean (Jun 19)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 19)
- Message not available
- Message not available
- Re: [c-nsp] Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 19)
- Re: [c-nsp] Devil's Advocate - Segment Routing, Why? Saku Ytti (Jun 19)
- Re: [c-nsp] Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 19)
- Re: [c-nsp] Devil's Advocate - Segment Routing, Why? Saku Ytti (Jun 19)
- Re: [c-nsp] Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 19)
- Re: [c-nsp] Devil's Advocate - Segment Routing, Why? Randy Bush (Jun 19)
- Re: Devil's Advocate - Segment Routing, Why? Masataka Ohta (Jun 19)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 19)
- Re: Devil's Advocate - Segment Routing, Why? Robert Raszuk (Jun 19)
- Re: Devil's Advocate - Segment Routing, Why? Randy Bush (Jun 19)
- Re: Devil's Advocate - Segment Routing, Why? Dorian Kim (Jun 19)
- why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Randy Bush (Jun 19)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Masataka Ohta (Jun 20)
- Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?) Robert Raszuk (Jun 20)
- 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)