GLBP VS HSRP/VRRP

[amit-singh]

Hi Experts,

I Have implemented and worked on HSRP/VRRP and now just trying to get the GLBP. Before I configured that I have some doubts that I would like to get cleared :

I read the GLBP Docs and here are the points :

1. What is the main diff between the GLBP and HSRP except the GLBP group number/ Weighting and load-blacning methods. By this I mean How many AVG can be therre in a GLBP group and how many AVF can exists in a GLBP group.

2. I read this " HSRP standby routers have unused bandwidth that the protocol is not using. Although multiple virtual router groups can be configured for the same set of routers, the hosts must be configured for different default gateways, which results in an extra administrative burden " Why this is called as extra burden. If I use GLBP the other router whihc are not the AVG/AVF, they are also in listen state and will use the same HELLO mechanism as used in HSRP so why the HSRP mechanism is still written as extra burden.

3. Does GLBP use more than one AVF in a group.If yes How does GLBP choose a AVF. Say If I have 5 routes in a single subnet 192.168.1.x and I have set the priority to 150 on router. Now that will become the AVG and also the primary AVF. So will the other routers become the AVF and will also start forwarding the packets ???

regards,

-amit singh

[bhatia.sachin]

Hi Amit,

As per your questions,

1 There is only one AVG selected for the group and all other memebers of the same group become AVF including the AVG.

2.HSRP mechanism is written as extra burden coz HSRP inherently doesn't support Load Balancing over multiple links.Only the router which has highest priority becomes the forwarder(active router) and others remain in listen state.Though you can configure manually so that both routers forward traffic but still u cannot make traffic from a host or vlan to be forwarded by both routers at same time in HSRP.Here lies the difference and the extra burden.

3.router with highest priority will become AVG and it identifies the AVF's for the group and load balances between them and itself.Moreover you can specify the method by which load-balancing is to be performed.

GLBP has it advantages over HSRP & VRRP but keep in mind that its a distant third in terms of implementation.

Hope this helps,

regards,

Sachin

[Darren Ramsey]

We run GLBP in a 6000+ node Health Care System (Data Center and Campus) with no issues. The benefit of GLBP is a true Active/Active environment and if you are clever, you can design out STP completely except as a safety net.