devaprem12 wrote:
Hi all
what is the difference between high-availability using STP and high-availability using HSRP ? and what is the advantage of using HSRP rather than STP
Coz i can acheive redundancy in both cases .
Regards
Deva
You are talking about different layers here, STP provides redundancy at Layer-2 while HSRP (and equivalent protocols like GLBP, VRRP) provide first hop redundancy at Layer-3. You actually need both if you are to provide adequate redundancy.
With STP you can provision redundant links in your network and let STP handle the loop avoidance and reconvergence in case of a link failure. However, if your end hosts' default gateway fails then only relying on Layer-2 redundancy will not help as the first hop will become unreachable. With HSRP you can provide this Layer-3 level of redundancy as well whereby if the HSRP Active device fails the Standby takes over and end devices can continue to utilize network resources.
In short, in a redundant network you will need both STP and HSRP (or GLBP/VRRP) to provide an adequate level of redundancy to end users. There are best practices associated with how you manage both protocols together (for example making HSRP Active your STP Root as well) and there is adequate collateral available on Cisco's website for you to start reading on this and developing the basic concepts.
Hope this helps.
Atif
P,S: By the way there are designs where you can actually minimize dependence on STP or even avoid it at times but discussing those in this thread is not appropriate. Just for your reference some options are extending routing to the access, using VSS or vPC at distribution level.
