In my experience/personal opinion, compared to OSPF2/3, in a large ISP, ISIS: - has simpler and better, less bloated code. Think ISIS on Juniper. Think FreeBSD vs Linux. - is more modular to introduce new features. - has certain knobs which makes it a bit more useful for ISP (LSP lifetime/Max number of LSP fragments, etc). This is for a large single L1/L2/backbone area. There are at least 2 design options I would consider before switching to multi-area ISP design. With that said I know of at least two of the largest ISPs tat use OSPF and many use that favor ISIS so it really comes down to ISP's preference and NOC willingness to learn new unfamiliar protocol. BR On Thu, Nov 10, 2016 at 3:35 PM, Mark Tinka <mark.tinka@seacom.mu> wrote:
On 10/Nov/16 14:30, Joel M Snyder wrote:
In a world where you are doing well-controlled Cisco/Juniper/etc networks with fairly homogeneous code bases, the engineers get to have this discussion. When you have to link in devices for which routing is not their primary reason to exist, your options narrow very quickly. It's not ideal; that's just the way it is.
Quagga's IS-IS implementation is a great example.
Mark.