Messages in this thread |  | | Subject | Re: [PATCH] strict interface arp patch for Linux 2.4.2 | From | "Allen Lau" <> | Date | Thu, 20 Sep 2001 19:34:21 -0400 |
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Julian Anastasov <ja@ssi.bg> on 09/20/2001 06:19:04 PM
To: Allen Lau/Raleigh/IBM@IBMUS cc: linux-kernel <linux-kernel@vger.kernel.org> Subject: Re: [PATCH] strict interface arp patch for Linux 2.4.2
Hello,
On Thu, 20 Sep 2001, Allen Lau wrote:
>> I want to bring your attention to a Linux ARP patch we plan to use for load balancing and server >> clustering. The available arp filter and hidden patch are not completely satisfactory. The following
> Can you explain what setup can't be build using arp_filter, > hidden or rp_filter and particulary where "hidden" fails for clusters, > it is very interesting?
The function provided by "hidden" is a necessary element but not sufficient. I suppose arp_filter has to be combined with the hidden patch. I dislike hiding an interface, and the hidden patch is no longer included in the major distributions which makes delivering a solution difficult.
In this example, 1.1.1.11 2.2.2.22 are virtual ip's which can float between boxes and interfaces. I want virtual ip 1.1.1.11 to be known to clients through eth0 node1 (2.2.2.22 eth1 node2). Node1 can redirect 1.1.1.11 traffic to eth0 node2. node1 node2 lo:1 1.1.1.11 lo:1 1.1.1.11 lo:2 2.2.2.22 lo:2 2.2.2.22
eth0 1.1.1.1 eth1 2.2.2.1 eth0 1.1.1.2 eth1 2.2.2.2 eth0:1 1.1.1.11 eth1:1 2.2.2.22
On node1, does hiding loopback hide 1.1.1.11? and can 2.2.2.1 be advertised as source ip in arp requests from eth0?
>> To generalize, each real server may have multiple nic's of different types. The task becomes one of ?> maintaining strict identity of each of the real and virtual ip addresses. The Linux ARP has the >> following behaviors which are problematic for maintaining strict interface identify. >> >> 1) box responds to arp on all interfaces on the same wire for an IP address (arp race)
> rp_filter and arp_filter can help here but this "arp race" is not > an evil in some setups
I believe "arp race" may cause purges in a switched network. It certainly is counter to maintaining strict interface identity.
Regards Allen Lau -- Julian Anastasov <ja@ssi.bg>
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