Tuesday, October 15, 2013

LACP 802.3ad and RHEL linux

In this post we will look at a basic 2x fast-ethernet port-channel using LACP between RedHat enterprise linux and a cisco switch.

1st here's the design;

First off LACP ( Link aggregation control protocol ) offers the following;

1: a mean to bundle similar (speed/type) links 

2: provides aggregated bandwidth

3: provides redundancy

In this scenario I'm using a cisco UCS460m2 server and ethernet 2 +3  under RHEL6.4  server.

Redhat Enterprise linux  has been support on UCS servers for a few releases now and this was my 1st install using 6.4 rhel

LACP operation mode was set for active on the cisco switch and the RHEL server also is active, What this means;

"Any side of the aggregation bundle, can active start the  session"

Here's valid configurations  modes for LACP ;

Here's a basic cisco  LACP setup & where the switch is actively attempting to start a session;

NOTE: The above config was applied on both  fast ethernets FAS 0/13+ 0/14 and the virtual port-channel number will be #1.

Okay let's look a real-interface on the RHEL-server;

Notice how we have no ipv4 address set on the real interfaces ? and we set the MASTER statement to reflect our virtual-interface named "bond0" for our eth2 and eth3 interfaces ?

To finally configure the RHEL we need a modprobe.d configuration file that we  named bonding.conf

NOTE:  The mode options #4 means LACP we could have installed 802.3ad also. You can read more here about bonding.


And finally after we restarted  the networking services, we can unix-cat our proc systems for net bonding and find that we are  truly bonded;

Or  by issuing cisco the  show  etherchannel summary commands  we can confirm from the cisco side of things

LACP  is support by almost all currently network vendors and almost by most common OSes.

 I've used LACP on a host of gear ranging from  cisco,juniper, fortinet, linux, Arista, and a few others vendors. It's also support  across  various interfaces from 10,100 megs or 1/10 gige.

LACP replaces the vendor specific channel-bonding that one might have seen from cisco and nortel.

I forgot to add a screenshot of bond0 virtual-interface, so here's a copy of how we created this interface. We also have a bridge setup  that's bonded to the 2 virtuals


We will later use these to bridge our vnic  and networks to the appropiate vlans on the hosting switch.

Ken Felix
Freelance Network / Security Engineer
kfelix  ----a---t---socpuppets ---d---o---t---com

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