Thank you Bryan, I couldn't have said it better. Besides, it is not clear from the trace provided that all ARPs are coming from the gateway anyway.
vector ----- Original Message ----- From: "Bryan Andersen" <[EMAIL PROTECTED]> To: "Patrick Colbeck" <[EMAIL PROTECTED]>; "Sebastiaan" <[EMAIL PROTECTED]>; "Vector" <[EMAIL PROTECTED]>; <debian-user@lists.debian.org> Sent: Thursday, June 14, 2001 2:53 AM Subject: Re: COM21 is killing me with ARP > Patrick Colbeck wrote: > > > > It really doesnt matter that there is a whole class B address space as > > you should only get arped when someone om the same class B needs to > > know your mac address. Once the arping device has your mac address it > > should cache it so it doesn't have to arp for it again for a long > > time. All the other people on the calls B shouldn't be trying to find > > your MAC address as they theoretically should only be talking to your > > service providers DSLAM. > > Actually it does matter. When Joe user turns off their box it > nolonger can answer requests for it's ethernet adderess. This > means a bunch of requests for it's arp address. So when > someone scans the network you get bombarded by arp requests, > and the caches naturally gets trashed durring this. If you > know a provider does this you can realy hose up their network > by bombarding them with random addresses in their network space. > To keep from having this trash a network the router really > needs to have enough cache entries to store all hosts on the > network. Many routers just can't handle that for a class B > network. They really should break their network up into > class Cs. > > > It sounds like somebody has screwed up at the service provider > > configuring their routers they have probably:- > > > > i) Configured a really small arp cache timeout value so the service > > provider router is permanatly having to re arp for the mac > > addresses of all the DSL modems or > > > > ii) Configured a static route via a broadcast interface (eg etherent) > > on the cental router. This is a really bad thing as instead of just > > arping for the next hop address the router will arp every time it > > needs to send a packet to any address on the network the route is for > > to try and determine the gateway to that address. This is a really > > good way to crucify network performance , static routes pointing at > > interfaces rather than next hop addresses should only be used on point > > t point networks (leased line etc). > > -- > | Bryan Andersen | [EMAIL PROTECTED] | http://www.nerdvest.com | > | Buzzwords are like annoying little flies that deserve to be swatted. | > | -Bryan Andersen | >