Implementing HA in a network

MAC_Addy

This isn't just a CCNA question, but a real world question for everyone. When implementing HA (HSRP, FHRP, etc) how are you designing your network to have a Cisco router handle DHCP for your network? My first thought is to have two main routers handling only the WAN connection and then another router handling ACL's and DHCP. The only thing is, what happens if that router goes down? A majority of my experience is with branch sites and we can (usually) only afford one router for each site.

networker050184

If you are going with a complex scenario like this it's best just to have a server handing out DHCP instead of routers. If it's a simple branch office with a single router then I'd use the router as a DHCP server.

jsb515

do you have a drawing ?

SteveO86

Depends on the scenario, and I've done this two different ways.

For really cheap customers, I had 2 WANs, with 2 routers, and I split the DHCP scope between the 2 WAN routers.

FHRP of course, for default gateway redundancy.

If you have only 1 router you could probably create SVI's on the L2/L3 switch and run DHCP on there. So if the router fails the switch can still give out DHCP address, but is it still worth it with the WAN down? All depends on the business.

Ask the business, how much money did this outage cost you? That could be a real easy way to get funding.