Layer 3 - "A small part of networking"

Node Man

Hi Everyone,
I was talking to a more experienced engineer recently and he said that usually there isn't much work to do with Layer 3. He said most of the layer 3 work is in the design and building the network, afterwords, layer 3 is left alone. He said most networking work is layer 1 and 2.

Does anyone have any feelings about this? Is layer 3 mostly a design and test&turn up issue?

networker050184

It really just depends on your job. If you are working on cabling and setting switchports yeah L1 and L2 are probably the majority of your job. If you're working in a complex routing environment then obviously you're going to be working with L3 more often than not.

aftereffector

That's hilarious. I'd love to know what ongoing layer 1 work this engineer is doing after his network is designed and built.

Node Man

aftereffector wrote: »

That's hilarious. I'd love to know what ongoing layer 1 work this engineer is doing after his network is designed and built.

Valid question - Service provider environment.

Iristheangel

I'd probably say ongoing L1/L2 work as a primary job duty (swapping cables/switches, checking fiber, etc) isn't really extensive network engineering work imho. You're also probably not going to be doing a ton of tuning of STP timers and other things once your network is up

On the other hand, if you're managing a large data center that requires L3 ECMP, managing multiple WAN circuits, failover, and even a L3 ECMP campus design, you'll probably find yourself troubleshooting or changing your routing table more often that tweaking your STP or L2 security. As you add new hosts, change designs to meet business drivers, etc. I would say that good L2 understanding and troubleshooting skills is a good attribute for a network engineer but if that's where you limit your skills at or don't put the majority of your efforts towards becoming strong in routing, you might find yourself limited in the job market.

Edit: Whoa. This is an SP environment? I'm very confused now. My understanding is that the majority of SPs have very very heavy BGP, IS-IS, and OSPF environments. Every time you have a new MPLS customer, that's quite a bit of work right there and it's definitely not spanning tree. I'm going to assume here for a second but does your employer use small siloed teams to deploy a single circuit? I.e. L1 team, L2 team, L3 team, etc? I've dealt with SPs that operated in that form and I had to work with 10 different teams just to get my sites turned up. Often one team didn't know the amount of work the other team was doing and they had tunnel vision on their specific job but not the project as a whole. If your coworker is part of one of those teams then from his perspective, he might not have been doing anything else for the last 10+ years and that's the whole part of networking for him. That being said, it doesn't usually translate to a massive amount of jobs outside that one gig he has so in order to have practical skills that you can use, I would urge you to disregard that feedback he gave you and make sure you have solid routing and switching skills and understanding.

networker050184

In the SP world there are usually teams of people that work with turn ups. Usually consists of ensuring cables are connected correctly, ports are configured etc. Those people usually aren't part of the team that engineers the backbone.

d4nz1g

Maybe he works on the access/pre-agg side, where you play with QinQ, REP, IRB, AToM/VPLS, etc.

beads

Documentation certainly comes to mind on the L3 side but hey we don't need no stinkin' documents around here. Ummm... until its time to troubleshoot something.

Smart call. Any chance this guy worked for my current client?

- b/eads

Iristheangel

d4nz1g wrote: »

Maybe he works on the access/pre-agg side, where you play with QinQ, REP, IRB, AToM/VPLS, etc.

True. He could. Still a lot going on in layer 3. There's a pretty good CCIE SP book out there floating around if the OP wants to balance those skills a little more: https://leanpub.com/ccie-spv4-comp-guide
Yes, CCIE sounds intimidating in the title but I know a couple folks using the book to grasp CCNP SP-level material

Fadakartel

Probably hes referring to the stuff in the ISP world? Like Sonet/SDH/OTN and DWDM those are at layer 1/2.

Cisco neither Juniper really goes into SDH/DWDM/OTN and SONET stuff really. I currently manage a subsea fiber network and trust me none off it has anything to do with QinQ, REP, IRB, AToM/VPLS.

If your looking to learn transmission (layer 1/2) you should check out vendors like Ciena, Huawei and Alcatel (now nokia )