[c-nsp] MACFLAP Message

j.vaningenschenau at utwente.nl j.vaningenschenau at utwente.nl
Mon Jun 28 04:55:15 EDT 2010


Bill,

In addition to Paul's comments: if the main reason for your current
setup is redundancy (and not capacity), you can try using a different
bonding mode on the server. If you use bonding mode 1 (active-backup),
only one of the links is used for traffic.

In bonding mode 1, there are two ways to determine which link is active:
miimon and ARP monitoring. I generally prefer ARP monitoring since it's
end-to-end, while miimon only monitors link state. So if the access
switch holding the "active" bond member has a link failure to your core,
miimon doesn't notice. With ARP monitoring, you can monitor specific
targets (either the default gateway IP or one or more addresses of other
Oracle servers). The bonding will fail over to the backup member if the
configured target(s) aren't reachable over the active link.

We're running mode 1 bonding for a similar setup, where each server does
ARP monitoring to two remote servers. Works like a charm. We decided not
to do ARP monitoring for the gateway IP, because that would impose an
unnecessary load on the CPU of our routers.

You might want to read up on Linux bonding options:
http://www.linuxfoundation.org/collaborate/workgroups/networking/bonding
.


Regards,

Jeroen van Ingen
ICT Service Centre
University of Twente, P.O.Box 217, 7500 AE Enschede, The Netherlands


----Original Message----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Bill Blackford
Sent: zondag 27 juni 2010 16:55 To: cisco-nsp at puck.nether.net
Subject: [c-nsp] MACFLAP Message

> Had an issue the other day that may or may not be related to the
> following message. 
> 
> Jun 24 11:30:37.354: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.1761.8140 in
> vlan 311 is flapping between port Po4 and port Po5 
> Jun 24 11:30:51.665: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.176f.a6e4 in
> vlan 311 is flapping between port Po4 and port Po5 
> Jun 24 11:30:52.672: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.1761.8140 in
> vlan 311 is flapping between port Po5 and port Po4 
> Jun 24 11:32:18.924: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.176f.a742 in
> vlan 311 is flapping between port Po5 and port Po4 
> Jun 24 11:32:24.460: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.176f.adae in
> vlan 311 is flapping between port Po5 and port Po4 
> Jun 24 11:34:12.237: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.176f.a6e4 in
> vlan 311 is flapping between port Po4 and port Po5 
> Jun 24 11:34:12.900: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.176f.adae in
> vlan 311 is flapping between port Po5 and port Po4 
> Jun 24 11:34:13.278: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.176f.a742 in
> vlan 311 is flapping between port Po5 and port Po4 
> 
> 
> VLAN311 is an Oracle heartbeat L2 vlan that spans across the data
> center. This message was logged on the 3750 VC stack (core). Each
> node is connected to access switches that each connect into the core
> via LACP bundles. Each of these MAC's are part of a Linux BOND group
> on various hosts. IOW, each bond interface member connects to each of
> the (in this case) two access switches. The topology is loop free
> from the perspective of the network switches as the LACP bundles
> eliminate the need for spanning tree. Now, this may be more of a
> question for how Linux bonding works across multiple access switches
> but I need to start here. I'm not finding a lot of information about
> this message. Does anyone on the group have any insight?          
> 
> Thank you in advance,
> 
> -b




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