nanog mailing list archives
Re: IP4 address conservation method
From: William Herrin <bill () herrin us>
Date: Thu, 6 Jun 2013 17:19:26 -0400
On Thu, Jun 6, 2013 at 3:00 PM, Bjørn Mork <bjorn () mork no> wrote:
William Herrin <bill () herrin us> writes:On Wed, Jun 5, 2013 at 6:25 PM, Ricky Beam <jfbeam () gmail com> wrote:I won't argue against calling Linux "wrong". However, the linux way of dealing with ARP is well tuned for "host" and not "router" duty.I love Linux and use it throughout my work but I can't tell you the number of times its ARP behavior has bitten me. If you send a packet to a VIP on a Linux box and it doesn't have an arp entry for the default gateway, the Linux box will send an arp request... with the vip as the source. That is just wrong. Wrong, wrong, wrong. Use the damn interface IP when you arp for something on that interface. If the router doesn't happen to like the bad arp (since the VIP isn't on the router's LAN) the router will ignore it. And your service will merrily pop up and down depending on whether the Linux box has any traffic to originate.Did you try setting sys.net.ipv4.conf.all.arp_announce=2 ?
Yes, of course I changed the sysctl. Yes of course that worked. Every time I've run in to the problem. On server after server after server.
Yes, the system default may be tuned for host/desktop usage
No, it doesn't default to reasonable desktop settings for ARP... it defaults to a version of wrong that on a desktop with one NIC and one IP doesn't happen to break anything. It'd be nice if it defaulted to RFC compliant instead and let the few folks with wacky needs move it off the standard behavior. -Bill -- William D. Herrin ................ herrin () dirtside com bill () herrin us 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004
Current thread:
- Re: IP4 address conservation method, (continued)
- Re: IP4 address conservation method Blake Hudson (Jun 06)
- Re: IP4 address conservation method Tore Anderson (Jun 06)
- Re: IP4 address conservation method Blake Hudson (Jun 06)
- Re: IP4 address conservation method William Herrin (Jun 05)
- Re: IP4 address conservation method Mikael Abrahamsson (Jun 05)
- Re: IP4 address conservation method William Herrin (Jun 05)
- Re: IP4 address conservation method Mikael Abrahamsson (Jun 05)
- Re: IP4 address conservation method Dan White (Jun 05)
- Re: IP4 address conservation method Mikael Abrahamsson (Jun 05)
- Re: IP4 address conservation method Ricky Beam (Jun 05)
- Re: IP4 address conservation method William Herrin (Jun 05)
- Re: IP4 address conservation method Bjørn Mork (Jun 06)
- Re: IP4 address conservation method William Herrin (Jun 06)
- Re: IP4 address conservation method Jimmy Hess (Jun 06)
- Re: IP4 address conservation method William Herrin (Jun 06)
- Re: IP4 address conservation method Bjørn Mork (Jun 07)
- Re: IP4 address conservation method rdrake (Jun 05)
- Re: IP4 address conservation method Jimmy Hess (Jun 05)