this post was submitted on 18 Apr 2024
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So can't a router do the VLAN stuff?
Your question exposes a language problem.
A router cannot do that. A router connects two networks together and routs traffic between them. That is it.
A home “router” is a combination device that includes a router, a wireless access point, maybe a modem, a managed switch, a dhcp server, a firewall, and more.
If you need a managed switch with more than 4 ports… you buy a managed switch. It is simple.
I feel like routers are overhyped.
An L3 switch is a router. Though most of them don’t have enough resources to take a full BGP routing table, at wire speed.
Think a large office space or industrial application with several hundred (or thousands) of hosts connected to the network. Some of them need to be isolated from the internet and/or rest of the network, some need only access to the internet, some need internet and local services and so on.
With that kind of setup you could just run separate cables and unmanaged switches for every different type of network you have and have the router manage where each of those can talk to. However, that would be pretty difficult to change or expand while being pretty expensive as you need a ton of hardware and cabling to do it. Instead you use VLANs which kinda-sorta split your single hardware switch into multiple virtual ones and you can still manage their access from a single router.
If you replace all the switches with routers they're quite a bit more expensive and there's not too many routers with 24 or 48 ports around. And additonally router configuration is more complex than just telling the switch that 'ports 1-10 are on vlan id 5 and ports 15-20 are on id 8'. With dozens of switches that adds up pretty fast. And while you could run most routers as a switch you'll just waste your money with that.
VLANs can be pretty useful in home environment too, but they're mostly used in bigger environments.
Thank you so much for writing that out.
A router usually can do all that but it also does a whole lot more, like NAT, DHCP, etc. Sometimes you need a just a switch that understands VLANs and link aggregation
A router is often just a switch with extra steps.
Yeah the line can get pretty ambiguous. In general I try to use the device with the least complexity that still gets the job done
So a router simply connects the WAN with the LAN. But doesn't the modem do that?
No, a modem modulates and demodulates a signal. Basically, they're a converter. For example, to send your Ethernet traffic over coax. They don't often understand or care about what's in an Ethernet frame.
Thank you
Isn't there some overlap between NAT, DHCP and DNS, they feel like they should be the same thing? Or am I oversimplifying it? Because DHCP is assigning IP addresses, DNS is looking up IP addresses and NAT is saying that IP address points there 👉🏾
Absolutely no overlap. Now, can a conventional home router do all those? Typically NAT and DHCP, but not too often DNS (except to point at a real DNS). That's like saying "isn't there overlap between milk and eggs? I mean, sure, they deal with animals and stored in the fridge, but used for different purposes."
Sure, they deal with IP addresses and some devices (home routers) can do 2-3 of those fuctions, but that doesn't mean they overlap. I can read a book (IP) and my book (IP) can be stored in a book bag or on a book shelf, but that doesn't mean myself, the bookbag, and the bookshelf overlap.
Thank you