Date: Mon, 25 Sep 2000 10:41:39 +0200 (CEST) From: Christian Kratzer <ck@toplink.net> To: Tom Samplonius <tom@sdf.com> Cc: sthaug@nethelp.no, abcjr@southwind.net, freebsd-isp@FreeBSD.ORG Subject: RE: Using 'private net' IPs for WAN Addresses Message-ID: <Pine.BSF.4.10.10009251037370.24025-100000@babylon.toplink.net> In-Reply-To: <Pine.BSF.4.05.10009242208260.3189-100000@misery.sdf.com>
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Hi, On Sun, 24 Sep 2000, Tom Samplonius wrote: > > On Mon, 25 Sep 2000 sthaug@nethelp.no wrote: > > > > > Here is a great description on why one should not use RFC 1918 addresses > > > > for inter-router links: > > > > > > > > http://www.worldgate.com/~marcs/mtu/ > > > > > > Wow... MTU path detection. Most routers use the same MTU on all > > > interfaces, so it isn't a factor. > > > > Sorry, that's wrong. There are plenty of routers with 1500 byte Ethernet > > MTUs, and considerably higher MTUs on serial/ATM/SDH interfaces. > > Then it is factor. Many networks have hundreds routers and not one with > anything other than 1500. Besides an interior network lines link with > >1500 MTU isn't going to lead to fragmentation if everything else is 1500. > Serial, ATM, SDH, etc. aren't really an issue, because so few devices that > originate traffic (ie. servers) live on them. However, gig ethernet is a > major problem. > > > > Next, if you assign a /30 for every p2p interface, you can only achieve > > > 50% utilization of the address space (2 used out of 4). That isn't enough > > > to meet the threshold to get more address space. I know a a network > > > provider that is numbering hundreds of p2p links just to free up address > > > space because they don't meet the density requirements. > > > > So you have only 50% utilization of the address space for your p-p links. > > Unless you are very different from other providers, this is going to be a > > very small fraction of your total address space. ripe understands the need for ptp links and counts networks used for /30s with 100% utilisation. Furthermore ripe uses the total ip's in your assignments to determine usage ratio of your allocations and does not go into the assignments to count your customers actually pingable ip's or similar ... Of course assignments are audited regularly when you get a new allocation but this is ok with me. Looks like we are very lucky to live in ripeland versus arinland ... Greetings Christian -- TopLink Internet Services GmbH ck@171.2.195.in-addr.arpa Christian Kratzer http://www.toplink.net/ Phone: +49 7032 2701-0 Fax: +49 7032 2701-19 FreeBSD spoken here! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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