The state of IS-IS

I would like experienced network engineers to comment on the state of IS-IS in today's networks. I personally have never encountered it but I've never worked at the SP level.
1. Do you still encounter IS-IS in today's networks and in what type of designs or environment(SP for example) do you see it?
2. Have YOU ever implemented it in a production network and how widespread do you think it is right now in your opinion?

Even if you've never encountered it, I would still appreciate your experts opinion.
Thank you.

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Comments

srg

It's real common in the SP realm, probably not so much outside of that

FloOz

It's the backbone protocol for fabricpath. When I learned that I was shocked since I have never even used IS-IS before.

reaper81

It is the link state protocol of choice by many SPs. I got exposed to it when I was working at an ISP. Later at another job they had a metro provider network and that ran ISIS as well.

Both TRILL and Fabricpath are based on ISIS. Because it uses TLVs it's very extensible.

Jackace

Like others have said. I work at a SP and IS-IS is our core routing protocol. It was implemented before I came to the company, but the main reason many SPs use it I am told is because it is less chatty then OSPF and scales better when you put all core routers in one big area. From the research I have done there are pros and cons to both OSPF and IS-IS so I'm sure you could probably use either these days.

powmia

Jackace wrote: »

Like others have said. I work at a SP and IS-IS is our core routing protocol. It was implemented before I came to the company, but the main reason many SPs use it I am told is because it is less chatty then OSPF and scales better when you put all core routers in one big area. From the research I have done there are pros and cons to both OSPF and IS-IS so I'm sure you could probably use either these days.

IS-IS and OSPFv3 would be a more accurate comparison.

fredrikjj

FloOz wrote: »

It's the backbone protocol for fabricpath. When I learned that I was shocked since I have never even used IS-IS before.

But you don't need to know any IS-IS to use TRILL because that control functionality is hidden/automatic/whatever the correct terminology is.

Routerronin

The cool thing about OSPFv3 is that scalability will cease to be an issue....once it is properly implemented.

Jackace

powmia wrote: »

IS-IS and OSPFv3 would be a more accurate comparison.

Yes OSPFv3 scales a lot better than OSPFv2.

networker050184

Dieg0M wrote: »

1. Do you still encounter IS-IS in today's networks and in what type of designs or environment(SP for example) do you see it?

As others have stated, it's still widely used in the SP ream.

Dieg0M wrote: »

2. Have YOU ever implemented it in a production network and how widespread do you think it is right now in your opinion?

We are in the process of migrating some acquired SP networks from OSPF to ISIS so I have been working quite a bit with it lately. I've never seen it used in an enterprise network though so how widespread depends on where you are looking I suppose.

Iristheangel

Our previous network architect was a former service provider guy and REALLY wanted to deploy IS-IS in our enterprise. He ended up getting shot down by the rest of the networking team but management ALMOST swung his way. Part of me almost wish it had just so I could have deployed it and seen how it works in a production environment but I realize that it probably wasn't the best option for our enterprise. Eventually, I plan on labbing it and learning more about it but it's not exactly high on my list of priorities.

Jackace

Iristheangel wrote: »

Our previous network architect was a former service provider guy and REALLY wanted to deploy IS-IS in our enterprise. He ended up getting shot down by the rest of the networking team but management ALMOST swung his way. Part of me almost wish it had just so I could have deployed it and seen how it works in a production environment but I realize that it probably wasn't the best option for our enterprise. Eventually, I plan on labbing it and learning more about it but it's not exactly high on my list of priorities.

One reason I know a lot of enterprises don't use IS-IS is if you do point-to-multipoint connections, like DMVPN, IS-IS doesn't support them.

Routerronin

Jackace wrote: »

One reason I know a lot of enterprises don't use IS-IS is if you do point-to-multipoint connections, like DMVPN, IS-IS doesn't support them.

DMVPN is custom made to work with EIGRP but can work with ospf and bpg. IS-IS may fade away because its not IP-centric enough.

Dieg0M

Thank you everyone, your opinion is much appreciated.

fredrikjj

You might find this interesting: Packet Pushers Show 89 - OSPF and IS-IS, comparing, considering and discussing

amb1s1

I don't know much about this new technology Shortest Path Bridging (SPB), but I think it use IS-IS. Shortest Path Bridging (SPB) will replace spanning tree. Again, don't know much about it.

networker050184

That is a good point amb1s1. SPB is supposed to use a stripped down version of IS-IS from what I hear. Another good reason to ensure you understand the protocol.

Dieg0M

Made a quick blog on this Hour 74: The state of IS-IS | RoutingNull0 - The Network Engineer Path and HTH brought up a good point in his comment.

Ryan82

Very prevalent in the service provider space as well as some very large enterprises. Some shops will just deploy a pure L2 backbone, others will have a mix of L1/L2. The ability to turn on another TLV instead of enabling another protocol to support ipv6 is one of the useful benefits of ISIS over OSPF that comes to mind.

nerdydad

Our Core is IS-IS, OSPF and IS-IS: Choosing an IGP for Large-Scale Networks: Choosing an IGP for Large-Scale Networks: Jeff Doyle: 9780321168795: Amazon.com: Books, is a great book if you want to learn about the idiosyncrasies of both protocols.