EIGRP vs OSPF
EIGRP or OSPF, one is not necessarily better, but rather just different. Both are tools you can use to solve a problem they’re well suited to solve. Unfortunately, nothing on either protocol goes into too much detail on why we would use one or the other. EIGRP is known widely as a proprietary protocol. So is it just a matter of using EIGRP with Cisco equipment and OSPF without? OSPF is pretty cool because it allows us to decide the path through the network by being aware of all links in a given logical topology. OSPF gives us a bit more control, seeing as each router knows about every other link in an OSPF area, allowing us to get really granular path selection. OSPF does require more resources on the device than most other protocols, such as the relatively light DUAL algorithm that sits behind EIGRP. So use OSPF when you have beefy equipment and EIGRP when you don’t. From what I’ve read Cisco will be allowing EIGRP to be used on non-Cisco equipment. That will make it more available to use. So now EIGRP may be kind of open and newer equipment is less affected by the power of OSPF. So back and forth we go. One thing where OSPF holds an advantage is the ability to see your route. With EIGRP it’s considered routing by rumor. EIGRP is able to summarize on any interface running EIGRP, and OSPF is only able to do this at Area Border Routers, or routers at that join multiple areas together. There are a couple ways of looking at this, but I’d like to make one very clear point. Any large network that actually requires summarization is likely managed by a team of route/switch individuals that have more or less a good idea of what proper network design looks like. In a properly designed routed topology, address spaces are contiguous and networks are hierarchical. Therefore, the ability to summarize at any point in the network really isn’t really something we need too terribly bad. EIGRP may allow us to summarize routes anywhere, but in a properly designed network at scale, the OSPF areas are in place to allow summarization where it makes sense.