Several of you have heard me talk about modular network design. There are five distinct advantages of a modular network design.
You can upgrade pieces easier than all-in-one devices. Being able to upgrade a certain module for that big new client might mean the difference between being able to do it in 10 days instead of 30.
You can avoid single points of failure. You are not depending on “big iron” for everything. You have multiple modules as a part of your design.
If routers, switches, access points, or whatever are doing less then you get better performance out them. CPUs are dedicating more time toward less processes. This results in better performance. Routers that are doing just BGP are able to process route tables better than ones doing stuff like OSPF or radius.
You are less dependent on certain vendors, or product families. Instead of having some big router that does BGP, OSPF, and other functions you can have a modular design where a router does, lets say, just BGP. Now you have more choices in hardware because it might not. This allows you to try out newer products or new product features.
5.Easier to maintain
Doing software upgrades on a modular devices, which is doing less things, means bugs and interoperability things don’t happen as often. Every piece of code has bugs. If the device is doing 5 tasks instead of 15 then the chance of a bug affecting the device is less. It also allows you to compartmentalize certain parts of the network.