GLBP load balancing

Answered Question
Jul 17th, 2009
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I would like to load balance between our MPLS circuit and IPsec tunnel. Preferrable solution will be to load balance after MPLS circuit reaches 80% load of the bandwidth. I understand that AVG responds the ARP for default gateway IP address, now how long the PC will keep the ARP cache (the MAC table)? I am thinking about GLBP Weighted Load balancing algorithm, i am trying to find out if the weighted load balancing only works for a percentage of the hosts rather than a percentage of the load of circuit (for example when all pc's boot 20% of pc will have vMAC for a particular AVF till the pc reboots again? or is it an AVF will become active as a forwarder when a particular circuit reaches 80% load?). Any help will be appreciated.

Correct Answer by Giuseppe Larosa about 7 years 10 months ago

Hello Rajib,


GLBP will work well if multiple clients are present for the fact that AVG answers to ARP requests with AVF MAC addresses.


GLBP priority has two dimensions:

priority to elect AVG

weighting to elect AVFs


Depending on the IOS version you can use object tracking to modify weighting if it is less the lowest threshold device gives to act as AVF.

If you find a way with object tracking to check load usage on interface you could modify weighting accordingly.


However, object tracking is usually used to check wan link healths (including icmp probes)so I'm not sure you can use GBLP with a "backup logic" based on load on primary link.


Hope to help

Giuseppe

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Correct Answer
Giuseppe Larosa Fri, 07/17/2009 - 05:50
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Hello Rajib,


GLBP will work well if multiple clients are present for the fact that AVG answers to ARP requests with AVF MAC addresses.


GLBP priority has two dimensions:

priority to elect AVG

weighting to elect AVFs


Depending on the IOS version you can use object tracking to modify weighting if it is less the lowest threshold device gives to act as AVF.

If you find a way with object tracking to check load usage on interface you could modify weighting accordingly.


However, object tracking is usually used to check wan link healths (including icmp probes)so I'm not sure you can use GBLP with a "backup logic" based on load on primary link.


Hope to help

Giuseppe

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