nanog mailing list archives
RE: Stupid Question maybe?
From: "David Edelman" <dedelman () iname com>
Date: Wed, 19 Dec 2018 16:45:04 -0500
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 You could be sure of two things when there were ambiguities in the routing tables: 1- Every manufacturer knew how to handle them. 2 - Every manufacturer did it a different way. I suspect that in most cases where two conflicting route entries existed, the router selected the first one that it encountered unless they were advertised using different protocols, then the priority associated with the protocol was used as a tie breaker. Dave - -----Original Message----- From: NANOG <nanog-bounces () nanog org> On Behalf Of Owen DeLong Sent: Wednesday, December 19, 2018 3:47 PM To: Thomas Bellman <bellman () nsc liu se> Cc: nanog () nanog org Subject: Re: Stupid Question maybe?
On Dec 19, 2018, at 12:11 , Thomas Bellman <bellman () nsc liu se> wrote: On 2018-12-19 20:47 MET, valdis.kletnieks () vt edu wrote:There was indeed a fairly long stretch of time (until the CIDR RFC came out and specifically said it wasn't at all canon) where we didn't have an RFC that specifically said that netmask bits had to be contiguous.How did routers select the best (most specific) route for an address? If the routing table held both (e.g.) 10.20.30.0/255.255.255.64 and 10.20.30.0/255.255.255.32, then 10.20.30.97 would match both, and have the same number of matching bits. /Bellman
The institution of the longest match rule came with the prohibition (deprecation) of discontiguous net masks. Owen -----BEGIN PGP SIGNATURE----- iF0EARECAB0WIQQP+UHquEepll566aqXCCyZOY1FIQUCXBq72AAKCRCXCCyZOY1F IVcSAKDwHTb8NranEYcejX1CJQwz0h318QCfSBzQMCiJ2uZwOxt3gvPTe3f38KE= =HMXc -----END PGP SIGNATURE-----
Current thread:
- RE: Stupid Question maybe?, (continued)
- RE: Stupid Question maybe? Naslund, Steve (Dec 19)
- Re: Stupid Question maybe? Patrick W. Gilmore (Dec 19)
- RE: Stupid Question maybe? Naslund, Steve (Dec 19)
- Re: Stupid Question maybe? Adam Atkinson (Dec 20)
- Re: Stupid Question maybe? Smoot Carl-Mitchell (Dec 20)
- Re: Stupid Question maybe? valdis . kletnieks (Dec 19)
- Re: Stupid Question maybe? Thomas Bellman (Dec 19)
- Re: Stupid Question maybe? William Herrin (Dec 19)
- Re: Stupid Question maybe? Thomas Bellman (Dec 19)
- Re: Stupid Question maybe? Owen DeLong (Dec 19)
- RE: Stupid Question maybe? David Edelman (Dec 19)
- Re: Stupid Question maybe? Baldur Norddahl (Dec 19)
- Re: Stupid Question maybe? Joe (Dec 19)
- Re: Stupid Question maybe? valdis . kletnieks (Dec 19)
- Re: Stupid Question maybe? William Allen Simpson (Dec 20)
- Re: Stupid Question maybe? Saku Ytti (Dec 20)
- Re: Stupid Question maybe? Joel Halpern (Dec 20)
- Re: Stupid Question maybe? Tony Finch (Dec 24)
- Re: Stupid Question maybe? Chuck Church (Dec 26)
- Re: Stupid Question maybe? Baldur Norddahl (Dec 18)
- RE: Stupid Question maybe? Naslund, Steve (Dec 18)