Questions on network design (for a beginner)

the_dude7

This is kind of a general question about network layout/design. Obviously for entry-level jobs in this field you probably wouldn't be in charge of actually designing a network from scratch for an org, but rather working on administering an existing one. And the network's design would be based on the needs of the organization and the way it's various branches are divided up, of course.

Anyway, I now know most of the commands from going through the Lammle book, but there wasn't much on the actual planning out of networks themselves. I was playing around with packet tracer trying different ways of arranging routers and switches, including looking for ways that wouldn't make sense. Could the following from this screenshot make any sense? I have a switch in between two routers, and it's connected to some hosts. Could that actually work with the following IP addressing scheme? Just for fun, I made the default gateway for the desktop PC the 10.1 on router 0 and the gateway for the neighboring laptop the 10.2 interface on router 1.



From what I've mostly seen, switches tend to be behind routers in stub networks rather than between two of them.

This might be a dumb question, as I haven't had proper sleep lately haha.

Fulcrum45

I think it would work. Not that having two different potential gateways on the same subnet is ideal nor can I think of a reason why one would design something this way. I suppose there could be scenarios that would benefit from this setup but I'll be darned if I know. I guess I don't know how the routers would handle outbound traffic between one another.

TechGuru80

As you have said the design usually doesn't happen at the CCNA level...CCNP or the design track both start to dive into how to set things up. At a high level, there are different layers (Core, Distribution, Access) and you generally wouldn't have hosts connecting to the last appliance prior to going to the internet. For the documentation, you would want to have each interface labeled...so for instance on the right half, you would have that switch interface and the router interfaces labeled...you currently have one IP on each segment and it's not clear which interface has the IP assigned.

the_dude7

I think it would work. Not that having two different potential gateways on the same subnet is ideal nor can I think of a reason why one would design something this way. I suppose there could be scenarios that would benefit from this setup but I'll be darned if I know. I guess I don't know how the routers would handle outbound traffic between one another.

Yeah that's kind of what I was wondering about, hence why I created a weird scenario like that.

As you have said the design usually doesn't happen at the CCNA level...CCNP or the design track both start to dive into how to set things up. At a high level, there are different layers (Core, Distribution, Access) and you generally wouldn't have hosts connecting to the last appliance prior to going to the internet. For the documentation, you would want to have each interface labeled...so for instance on the right half, you would have that switch interface and the router interfaces labeled...you currently have one IP on each segment and it's not clear which interface has the IP assigned.

Thanks. So most modern networks generally follow some form of the 2 or 3 tier hierarachical (core, distribution, access, or collapsed core) setup? What are some examples of good network topology

networker050184

the_dude7 wrote: »

What are some examples of good network topology

One that meets the needs. That can be a single device, a two tiered approach, three tiered, etc. just depends. Way too many people design a network based on some Cisco doc they read and then try to fit all their needs into it. Do it the other way around and you'll have more success.