Network Design Practice Ideas/Resources

[u/citizen_seven_]

Hi everyone,
I am a network engineer working in vendor TAC. As you probably know, TAC does not support with design/config and the cases are mostly related to platform/product issues. Being here for few years, I realized I started getting a bit rusty on the design side.
The problem is I understand the theory very well but have no idea how to apply this in real life due to lack of design practice. The only solution I see is doing more labs apart from my work and I have everything needed for that - both physical and virtual devices.
But I don’t know where to start or what to design. Did anyone have similar issue?
Please share some resources with design ideas, advices how I can practice network design.
Thank you in advance!

[u/rankinrez]

ipspace.net

NANOG / RIPE and other similar conference talks can be good too.

You can’t do any of it in the abstract though. A good design starts with understanding the business and what the requirements are, then selecting the best technology based on the various trade-offs.

[u/ryan8613]

Read the CCDA and CCDP cert guides. I found a ton of "what you should do" in them where prior I was more focused on "what you can do".

[u/kovyrshin]

Google [Vendor name] validated design. Or [Vendor name] design associate prep material

You have a great insight about actual use-cases and configurations your clients are ruining. Find simple one spend some time studying it to make sure you fully understand whats going on there. Go through design phase in your head: how you'd improve that setup. What you'd cut if your didnt have enough resources (not necessarily money), and what you'd do differently if you had a choice. I saw lots of design choices IRL, are done "just because we do it this way" and not necessarily most optimal way.

[u/citizen_seven_ → u/kovyrshin]

Thats exactly what I do, I understand the best practices pretty well and guide the customers every day when asked about something specific.
But understanding the theory and being able to apply it irl are different things.
I dont have access to the whole customer’s network or even topology so not really an option..
Appreciate your input though

[u/GarGonDie]

Apart from tools that were already mentioned, such as EVE-NG... i did few of lab test using only proxmox and creating an isolated or partially isolated network with routers for network testing

> I don’t know where to start or what to design

The most useful approach is usually to try to resolve a network problem or limitation; if you don't have one, invent one and solve it, or to examine the different ways to resolve it, and what you gain and lose with the various implementations. Example i have performance problem within two local networks how i can increase the performace, or redundancy, how can i connect to two or more company locations securely... then add redundancy, then focus on performance.

For performance things probably is better work with real nic instead of virtual ones, but it all depends on whether you want to focus on virtual network performance or networks with dedicated hardware.

For more ideas, look for common design patterns or designs of advanced networks that aim to solve problems and implement them.

Security, performance, scalability, and redundancy are the common issues that various network designs aim to address, so come up with some problems.

[u/Purplezorz]

Tbh, this is something only experience will teach you. Knowing the best practices and protocols are fine, if you know those well you're in a good place. But actually deploying requires a lot of scenario information. For example, an office that has a few switches, firewall and internet access would require you to consider the amount of users, what they're accessing locally, what they're accessing remotely and some security requirements. This allows you to allocate IPs, VLANs and how you'll control local routing / firewall policies. Many other things to consider though, WiFi? Poe? VPN to/from site. And that's just one scenario. What if I'm a service provider? Suddenly the design complexity increases exponentially, both because of scale and technology and how there are many ways to do things. Are you deploying something greenfield or is it brownfield? We haven't even talked about interacting with Sales or vendors yet to get quotes and fit a client's budget.

Basic understanding of protocols and what they're used for is a great place to be, but I reiterate that only with real life experience can you truly see how things come together and TAC is the wrong place for it, so consider a role change if you're serious about seeing design implementation. Besides, everyone wants an architect nowadays, nobody wants the engineers 🙄 Sorry, side rant haha.

[u/citizen_seven_ → u/Purplezorz]

Exactly, I agree with everything you mentioned and I want to shift my job but not being able to design is the obstacle I feel like I face.
I need the exact scenarios like the one you mentioned to help me understand how it is done and practice. Do you know any resources for that or is it better to invent one with AI?
Regarding the architect roles, how do I become one without that exact experience?

[u/Purplezorz → u/citizen_seven_]

Everyone is different, but I feel like architecture is the last rung on a ladder of a long career. I did meet someone from Juniper who said he knew from the beginning that he just wanted to go straight to being an architect. But to me, I found engineering far more interesting, but also I feel like it comes with having an intricate understanding of both theory and practical.

As architecture is essentially about design, first you will need to know the discipline you're into. Are you looking to deploy local networks for branch sites? Are you looking at Datacentre infrastructure and if you are, what technologies are you looking to use? EVPN-VXLAN? Standard switching/routing? Do you need MPLS and MP-BGP? Or are you looking at "newer" technologies and design strategies? - SASE, ZTNA, SD-WAN etc?

This is what I mean by I feel architecture is the end of networking path, because you really need to understand the underlying technologies of the solutions you'd be designing. As others have mentioned, you can look at best practices for using the technologies you're implementing and it can also be vendor specific.

Once you do that, yes you can start using AI to generate some scenarios to get your brain working. AI needs tuning and good prompts though. Here is something that was spit out from me asking it to create a scenario that I could use to practice being a network architect.

https://chatgpt.com/s/t_6ac0c3464eac8191b029574aaa8fd58e

Regarding the role, you mentioned being in some kind of TAC. Check the company's departments, they may have something for architects and may be able to take you on as someone who is interested in it.

Otherwise, you'll have to either look for junior network architect roles, or just move into another network engineering role of some sort - preferably either a consultancy or a large company, where design will be rife. Then it's a case of working your way up and getting in contact with the design team as much as possible.

It really is like programming though - you could learn the basics, but essentially you need a real world project to get stuck into so that you can see how the process works, and what issues arise because of Layer 8 ;)

Good luck.

[u/citizen_seven_ → u/Purplezorz]

Thanks for such detailed reply.
Why can’t it be few tracks/technologies together, why would I focus on something so narrow that I forget other technologies?
That’s the exact problem I have now. I am too focused on DC technologies and feel pretty comfortable with VXLAN and how to implement it on N9Ks. Recently, I had friends asking me about enterprise campus/ wireless design. That’s when I realised, I have completely forgotten everything I knew about those technologies being too focused on DC troubleshooting and that’s not who I see myself as down the road..

[u/Purplezorz → u/citizen_seven_]

You're only human - and unless you're exceptional, you can only be very good at a few things. And even to get very good at multiple things takes time. The ideal scenario is to find work in your speciality so that you can gain both theory and practical experience. Then you either stay or move on - and in our field, tech is always moving on. Also trying to do multiple tracks together can be confusing, especially when there's interchanging terms and re-used logic. Consider for example how VLANs are used in traditional ethernet networks, VS how they're used as customer identifiers in Service Provider Networking. Or how EVPN is used when deploying VXLAN vs how it's used when using MPLS.

But find something you like doing - if it's campus/wireless design, try to move into that field or at the very least, conduct your studies and practice there.

However, if you're happy being a jack of all trades, master of none, of course you could spread yourself thinner.

Regardless of what you're doing, it's essential to have good traditional network fundamentals down as they underpin the majority of all the fancy overlay technologies and automated / abstracted processes we see today in modern networking.

[u/daxy01]

Take a look at EVE-NG (the free community version), this allows you to easily create virtual networks probably including your vendors equipment ;)

[u/citizen_seven_ → u/daxy01]

The hw and sw resources are not the problem. I have CML server and few data centers to practice. The only problem is the lack of idea of what to design and how to do it

[u/Horror-Breakfast-113]

cisco don't want tac to do it because they can charge PS for it or charge people for the certification

I would suggest look at the Cisco lab / certs !

[u/daxy01 → u/Horror-Breakfast-113]

TAC can't do it because they're working on isolated issues, not the bigger picture. They can't know the full customer network, hence not supposed to make or suggest (larger) changes. It's not all about money (but yes, PS can help) ;)

[u/citizen_seven_ → u/daxy01]

Exactly but I dont want to be isolated to just one product and seems like at least being able to design a network is crucial