Today we are going to see the last protocol of the First Hop Redundancy triad. GLBP, Gateway Load Balancing Protocol.

GLBP is a Cisco owned propietary protocol that supports load balancing besides gateway redundancy. From Cisco Systems official documentation we get this resume:

  • Provides load balancing
  • Supports IPv6
  • Port 3222 for transport
  • Default priority is 100
  • Hello interval is 3 seconds
  • Uses multicast address 224.0.0.102

There are 2 roles for GLBP routers:

  • AVG. Active Virtual Gateway. Is the virtual active router and assigns MAC virtual addresses to the other group members
  • AVF. Active Virtual Forwarder. Rest of routers that forward traffic

GLBP uses 3 methods to achieve load balancing:

  • Round-Robin. Default method. AVG responds to ARP requests from hosts to the virtual router with the next group member
  • Host-Dependent. Uses Round-Robin, an AVF is maintained for each host
  • Weighted. Determines the load balancing for host in each AVF

Again we are going to use the VRRP and HSRP topology. Now we have one more host in the 172.17.172.0/24 network. It’s R3 and we need it because for the gateway selection, GLBP uses the MAC address of the host that sends traffic.

Video:

08/19 – Video uploaded to Youtube