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Old 07-13-2011, 03:30 PM
Georgios Magklaras
 
Default Arp Cache issue

On 07/13/2011 03:34 PM, brian irvin wrote:

We are using bnx2 driver. We are getting outages when arp table fills up and unless we flush the table, network connectivity is an issue.

more ifcfg-bond0
DEVICE=bond0
BONDING_OPTS="mode=1 miimon=500 primary=eth4"


Thanks

Brian


Assuming that you obviously update the system via RHN to have the latest
and the greatest, I would check to see if your switch ports are
configured in some sort of peculiar mode. If the rest of the boxes you
run has a smaller arp table, then the switch port might be throwing a
lot of traffic because, for example, it might be in SPAN mode, throwing
all the traffic on the VLAN, when it does not need to be.


Failing that, if you have a large VLAN and more than a 1000 clients on
it, depending on the class of your subnet, you can turn into the
following ARP/IP kernel parameter:


sysctl -a | grep -i thresh

Have a look at this document:

http://www.clusterresources.com/torquedocs21/a.flargeclusters.shtml

which suggests amongst other things ARP flush parameters to put under
/etc/sysctl.conf


/etc/sysctl.conf

# Don't allow the arp table to become bigger than this
net.ipv4.neigh.default.gc_thresh3 = 4096
# Tell the gc when to become aggressive with arp table cleaning.
# Adjust this based on size of the LAN.
net.ipv4.neigh.default.gc_thresh2 = 2048
# Adjust where the gc will leave arp table alone
net.ipv4.neigh.default.gc_thresh1 = 1024
# Adjust to arp table gc to clean-up more often
net.ipv4.neigh.default.gc_interval = 3600
# ARP cache entry timeout

net.ipv4.neigh.default.gc_stale_time = 3600


--
--
George Magklaras PhD
RHCE no: 805008309135525

Senior Systems Engineer/IT Manager
Biotek Center, University of Oslo
EMBnet TMPC Chair

http://folk.uio.no/georgios

Tel: +47 22840535

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Old 07-13-2011, 04:49 PM
"J. D."
 
Default Arp Cache issue

There is am issue with older bnx2 kernel modules in rhel5. There is a kb
article that explains how to disable MSIX or update the kernel.
On Jul 13, 2011 8:38 AM, "brian irvin" <brian944us@yahoo.com> wrote:
> We are using bnx2 driver. We are getting outages when arp table fills up
and unless we flush the table, network connectivity is an issue.
>
> more ifcfg-bond0
> DEVICE=bond0
> BONDING_OPTS="mode=1 miimon=500 primary=eth4"
>
>
> Thanks
>
> Brian
>
>
> --- On Tue, 7/12/11, Georgios Magklaras <georgios@biotek.uio.no> wrote:
>
>> From: Georgios Magklaras <georgios@biotek.uio.no>
>> Subject: Re: Arp Cache issue
>> To: "General Red Hat Linux discussion list" <redhat-list@redhat.com>
>> Date: Tuesday, July 12, 2011, 9:41 PM
>> On 07/12/2011 09:46 PM, brian irvin
>> wrote:
>> > We have a RHEL 5 box which requires frequent flushing
>> of arp cache to stay up and running and not create network
>> bottlenecks. Anyone have these issues? we have quite a few
>> servers and have never faced an issue before this one. I
>> thought it might have to do with the switch but the network
>> folks say the switch is clear. Any thoughts??
>> >
>> > cat /proc/net/bonding/bond0
>> > Ethernet Channel Bonding Driver: v3.4.0 (October 7,
>> 2008)
>> >
>> > Bonding Mode: fault-tolerance (active-backup)
>> > Primary Slave: eth4
>> > Currently Active Slave: eth4
>> > MII Status: up
>> > MII Polling Interval (ms): 500
>> > Up Delay (ms): 0
>> > Down Delay (ms): 0
>> >
>> > Slave Interface: eth0
>> > MII Status: up
>> > Link Failure Count: 0
>> > Permanent HW addr: 00:37:c9:38:e3:3b
>> >
>> > Slave Interface: eth4
>> > MII Status: up
>> > Link Failure Count: 0
>> > Permanent HW addr: 00:11:17:4c:ee:22
>> >
>> >
>> > Thanks
>> >
>> > Brian.
>> >
>>
>> Can you clarify a bit the staying up and running/bottleneck
>> issue? What happens if you do not flush the ARP table in
>> terms of what you see in the system and what do you see on
>> the LAN side for the system? Also which Ethernet driver
>> module you use in the system?
>>
>> I have seen issues with IP aliasing (not HA bonding) on
>> very busy LANs, but long time ago, not on recent 5 releases.
>> As far as I know, unless you use a load balancing mode
>> bonding, the netwrk switch should not be tweaked.
>>
>>
>> GM
>>
>> -- -- George Magklaras PhD
>> RHCE no: 805008309135525
>>
>> Senior Systems Engineer/IT Manager
>> Biotek Center, University of Oslo
>> EMBnet TMPC Chair
>>
>> http://folk.uio.no/georgios
>>
>> Tel: +47 22840535
>>
>> -- redhat-list mailing list
>> unsubscribe mailto:redhat-list-request@redhat.com?subject=unsubscribe
>> https://www.redhat.com/mailman/listinfo/redhat-list
>>
>
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