[ewg] [PATCH] update docs/ipoib_release_notes.txt to educate users on arp_ignore etc

[Or Gerlitz]

Hi,

please review, I have refined the section on multi homed IPoIB hosts and
added the suggestion to user the arp_ignore param.

Sean, I suggest you will add pointer or repeat it in short at the rdmacm
release notes as miscorrect settings would also cause issues with rdmacm
usage on such hosts.

Or.

--- docs/ipoib_release_notes.txt.orig	2007-05-30 09:29:26.000000000 +0300
+++ docs/ipoib_release_notes.txt	2007-05-30 09:52:57.000000000 +0300
@@ -44,11 +44,19 @@ the path for inspecting the debug level
 ===============================================================================
 3. Known Issues
 ===============================================================================
-1. If a host has multiple interfaces, each belonging to a different IP subnet,
-   yet they use the same InfiniBand switch, the host may build an incorrect ARP
-   table. This may lead to problems which seem like violations of the IP rule
-   requiring different broadcast domains -- a rule not observed in this
-   implementation of IPoIB.
+1. A host that has multiple interfaces, each belonging to a different IP subnet,
+   yet they use the same InfiniBand Partition and are connected to the same IB
+   Switch, violates the IP rule requiring different broadcast domains and hence
+   may build an incorrect ARP table.
+
+   Thus the correct setting of multi-homed IPoIB host would be to use a different
+   PKEY for each IP subnet. When a host has multiple interfaces on the same IP
+   subnet, to avoid the case of a peer building an incorrect ARP entry (neighbour),
+   set the net.ipv4.conf.X.arp_ignore value to 1 or 2, where X stands for the
+   IPoIB interfaces (eg ib0.8002, ib1.8002, etc)
+
+   To learn more on the arp_ignore param, see Documentation/networking/ip-sysctl.txt
+   Note that distributions have the means to make kernel params persistent.

 2. On Fedora Core 4, SuSE 10 and SLES 10:
    a.   There are IPoIB alias lines in modprobe.conf which prevent stopping/