From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zdenek Radouch Subject: Re: Do you know the TCP stack? (127.x.x.x routing) Date: Wed, 09 Mar 2005 08:39:10 -0500 Message-ID: References: <20050306173145.GQ31837@postel.suug.ch> <3sp35g$7hpm0@smtp04.mrf.mail.rcn.net> <422C0B50.20500@mrv.com> <3sp35g$7rsc1@smtp04.mrf.mail.rcn.net> <1110288879.1050.167.camel@jzny.localdomain> <20050308135134.GA20607@atrey.karlin.mff.cuni.cz> <1110290300.1050.190.camel@jzny.localdomain> <20050308140301.GC20607@atrey.karlin.mff.cuni.cz> <1110291470.1043.211.camel@jzny.localdomain> <1110316631.1084.57.camel@jzny.localdomain> <1110371962.1088.90.camel@jzny.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Martin Mares , Eran Mann , Thomas Graf , Andi Kleen , netdev@oss.sgi.com, linux-net@vger.kernel.org To: hadi@cyberus.ca, Henrik Nordstrom In-Reply-To: <1110371962.1088.90.camel@jzny.localdomain> References: <20050306173145.GQ31837@postel.suug.ch> <3sp35g$7hpm0@smtp04.mrf.mail.rcn.net> <422C0B50.20500@mrv.com> <3sp35g$7rsc1@smtp04.mrf.mail.rcn.net> <1110288879.1050.167.camel@jzny.localdomain> <20050308135134.GA20607@atrey.karlin.mff.cuni.cz> <1110290300.1050.190.camel@jzny.localdomain> <20050308140301.GC20607@atrey.karlin.mff.cuni.cz> <1110291470.1043.211.camel@jzny.localdomain> <1110316631.1084.57.camel@jzny.localdomain> Sender: linux-net-owner@vger.kernel.org List-Id: netdev.vger.kernel.org At 07:39 AM 3/9/05 -0500, jamal wrote: >... >Lets list the options and assume there are two sets of addresses those >for inside the chasis and those for outside: > >1) Addresses for intra-chasis communication. >The addresses used by the blades are intrachasis relevant only and the >packets never leave the box. The blades are interconnected via some >L2/VLAN/bridge within the chasis. > >Conclusion: >If these packets never leave the box - no ARP will ever see them and no >dynamic routing protocol will ever advertise them - therefore no IP >address collision. You can use _whatever_ address you want, private >public, IBMs, intels etc. Do we agree on this? In other words hack not >needed here. No, I do not agree - you really need to re-read my last post carefully, making sure you understand what I am saying. Other people have illustrated the problem as well. Imagine a simple gateway, connecting two parts of your company - the east interface connects to a corporate net with a default gateway, the west net is the software dept. net. Now imagine that you give your internal line card in this simple gateway a "_whatever_" address, say 18.7.22.69. Your gateway now has a route 18.7.22.69/32 -> dev linecard Now please tell me what happens when a guy on the west net tries to check his MIT evening class schedule. >a) using private addresses implies possibility of conflict of addresses >within customer's network. To quote Zdenek: >You couldn't walk in the NOC and tell them: "You can't use the 10.x >net to manage your equipment - my box is already using that net". >Conclusion: >You walk into the NOC and say "can i use 10.0.0.x/22 subnet" they say "no >thats going to collide use 10.0.0.0/28" In real world, where you pay for addresses and for people's time, no one will give you *their* address for *your* interconnect. Not a public address, and not a RFC1918 address. Your interconnect is your problem, they are neither interested nor paid to deal with your design issues. >a') Using 127.x addresses. You -> NOC "can i use 127.0.0.x/22 subnet" I know I can use it. I own it as per RFC 3330. >So tell me what i am missing! Experience of having built a router. Sorry to be so blunt. -Zdenek