CISCO GLBP LOAD BALANCING OPTIONS:
Cisco Gateway Load Balancing Protocol (GLBP) is one of Cisco First Hop redundancy Protocols and it offers load balancing across multiple gateways. GLBP supports four types of load balancing options. How network hosts are assigned to each GLBP Router can be altered by using one of four load balancing options mentioned below. These options are not able to be deployed concurrently. There is a negligible CPU difference in the operation of either of these options.
There are four different types of Load balancing algorithms in GLBP:
2. Host dependent
4. Round robin
If no load-balance algorithm is specified then GLBP will operate in an identical fashion to HSRP, the AVG will only respond to Address Resolution Protocol (ARP) requests with its own Virtual Forwarder (VF) MAC address, and all traffic will be directed to the AVG with no occurrence of load balancing.
Cisco-glbp_1(config-if)#glbp 1 load-balancing ?
host-dependent Load balance equally, source MAC determines forwarder choice
round-robin Load balance equally using each forwarder in turn
weighted Load balance in proportion to forwarder weighting
- The Mac-address of the host is used to determine which AVF’s mac is the host directed towards.
- A given host is guaranteed to use the same Virtual Mac as long as number of VF’s in the GLBP group are constant
- Host dependant GLBP is not recommended in situation where there are small number of hosts, for example, less than 20
- GLBP places a weight on each device to calculate the amount of load sharing that will occur through MAC assignment
- Each GLBP router in a group will advertise its weight and AVG will act based on that value
- For example we have two routers, Router A and Router B. If router A has double the bandwidth capacity then router B. Router A will be configured with the double weighting value of router B
- With Round-robin VF mac-address is used sequentially in ARP replies for the virtual IP
- This is the default type of GLBP algorithm
- It is suitable for any number of hosts.
Filed Under: HSRP/VRRP/GLBP
About the Author: