Is a Router required to set up a network? [closed]

Question

Is a router required to set up a network?

Suppose I have just an Ethernet wire and then I fix it up to 3 computers.

Can I then say that these computers are now in a network? If they are in a network now without that router, with just the Ethernet wire alone, how and where is the network IP address and all that subnet mask going to be generated from? It is likely going to be a private address since it is local but who would assign the 3 computers with their own host IP without the router?

Answer 1

A DHCP server can still assign IPs without a router. DHCP is a layer 2 protocol and doesn't need a router to function. In fact, routers need to be configured specially to hand out IP addresses across a routed network.

The three computers would be considered on the same Layer 2 network, but their traffic wouldn't be able to leave it without a router.

If you don't have a DHCP server on the network, then the computers will autodiscover an available address on the 169.254.0.0/16 scope that is defined in RFC 3927 for just this situation.

Answer 2

Is a router required to set up a network?

No. But you won't be able to just fix an Ethernet cable to three hosts -- at least I've not seen 3-way-crossover cables. You'll need, at minimum, a hub.

Can I then say that these computers are now in a network?

Yes, you can say "these computers are now in a network". They are in a network in the described configuration.

how and where is the network IP address going to be generated from?

You would need to manually assign each node an IP, or run a DHCP service on the network to assign IPs.

who would assign the 3 computers with their own host IP without the router?

You assign the IPs, either manually or with DHCP. Note that without a router, all traffic will be local to the network.

Answer 3

Is a router required to set up a network?

No. Only to route traffic between networks.

Suppose I have just an Ethernet wire and then I fix it up to 3 computers.

That's pretty hard to do with modern Ethernet cabling since only star configurations are supported.

Can I then say that these computers are now in a network?

Yes.

If they are in a network now without that router, with just the Ethernet wire alone, how and where is the network IP address and all that subnet mask going to be generated from? It is likely going to be a private address since it is local but who would assign the 3 computers with their own host IP without the router?

First, IP is not a network requirement. You can have a network without any IP at all.

Second, many nodes can assign themselves IP addresses in a mechanism designed specifically to make a bunch of devices connected by a switch "just work".

Lastly, human beings can assign IP addresses and subnet masks to each device. Alternatively, you can run a DHCP server on one of the machines. You don't need a router to assign IP addresses.

Answer 4

ipv6 auto assigns a link local address and APIPA is a protocol designed to do the same for IPv41. A router is only required on a network when routing (getting packets to another network) is required. Ethernet cables are point to poin connections and cannot be created in a 3 headed configuration. A hub is the minimum required network device to connect more than 2 computers at one time.

Answer 5

A wire connects one piece of equipment to another. You cannot connect three PCs to each other with one wire.

If you do some trickery to physically, electrically connect three wires together, what you have essentially created is a passive hub - so yes, you can use this to network three PCs.

If you are using IP on a network with no DHCP server (this is a separate question - you can have a DHCP server with a hub, or lack one with a router), the computers will each automatically grab an IP in the 169.254.0.0/16 block (or fe80::/10 in IPv6). Windows refers to this as Automatic Private IP Addressing.