GLBP- Round Robin Load Balancing

[gnanavel.ns]

Dear All,

Just wanted to check if GLBP load balancing with Round Robin option will send traffic to two routers (part of the group) if there is only one host sending traffic.

My customer has got a setup where a single firewall is sending outbound traffic to 2 WAN routers (each terminating a WAN link) which will run GLBP in the LAN. The objective is to send traffic equally to both the routers and ultimately in the WAN, and not to load a single WAN link.

Thanks a lot for your time.

Regards

Gnanavel.      

[ALIAOF_]

So you have two internet routers setup with GLBP.  Both of them are connected to a switch I'm assuming and then you have your Firewalls inside interface connected to a switch.  Firewall is a default gateway for the hosts and then it is sending the traffic out to the VIP of the GLBP configured routers?

[Abzal]

Hi,

Round-robin load balance equally using each forwarder in turn. With Round Robin each VF MAC address is used sequentially in ARP replies for the virtual IP address. It's default method of load balancing on GLBP.

Hope it will help.

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

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Posting

No, GLBP won't balance (if it sees all traffic from the same MAC).

If the FW supports multi-path static routing, you might use mHSRP on both routers.

Or you might (optimally) outbound load balance using OER/PfR (if supported).

[ALIAOF_]

Joseph I have a question in regards to your post.  You mentioned if it is from the same MAC GLBP won't load balance.  I am running GLBP on two of my switches but I'm using the load balancing method as weighted.  So it would be different in that case?

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Mohammad Ali wrote:
Joseph I have a question in regards to your post.  You mentioned if it is from the same MAC GLBP won't load balance.  I am running GLBP on two of my switches but I'm using the load balancing method as weighted.  So it would be different in that case?

If I recall correctly, I don't believe it matters.  GLBP responds to a host's ARP request.  The different GLBP methods deal with what's returned to the ARP request, i.e. how the hosts are balanced across the GLBP group.  Each host, though, only has one destination MAC (for the gateway IP), so all traffic from that client will go to the same GLBP group member.

If you have multiple hosts, they will be divided (depending on GLBP method) among the GLBP group members.

[gnanavel.ns]

Thanks a lot Joseph, Muhammed, Abzal for your valuable inputs.

So, if it is a single host sending traffic, for example firewall, there is no way we can load balance using GLBP. All the traffic will always hit a single VRF.

Is my understanding correct?

Regards

Gnanavel.