intro to LAN (local area network)

topology

how everything is actually connected in a network

star topology

device are connected to a central networking device (switch/hub)

• all data is sent to the central device then to the destination device

• pros: can add a lot of devices

• cons: too many devices can be harder to maintain; is the central device fails the whole thing fails

bus topology

relies on a single connection (backbone cable) where the devices branch off it

• cons: prone to stalls since all the data is moved on the same cable; hard to know which device is having trouble

ring (token) topology

• devices are connected to each other

• sends data along the loop until it reaches destination

• a device only continues the cycle if it has no data of its own to send (if device2 has data but device1 also sent data, device2 will send its own first)

• easy to troubleshoot

• when one device doesn’t work, the whole connection fails

router

connects networks and passes data between them

• can be used to connect devices on different networks

switch

connects multiple devices to a router

• can connect 4,8,16,24,32, and 64 devices

• keeps track of what device is connect to which port

• uses packet switching to break down data

subnetting

splitting networks into smaller networks

• done with a subnet mask

• subnet mask: number of hosts that can be in a network

• format is similar to IPV4

• subnets uses the IP to find the network address, host address, and default gateway

network address

finds the start of the network (the parent network) and confirms it exists

• actual IP: 192.168.1.100

• parent IP: 192.168.1.0

the actual IP belongs to the parent IP

host address

identifies the device on the subnet

default gateway

special address of the router

• if destination is on a different network

• uses the first/last host address (.1 or ,254)

ARP (address resolution protocol)

allows devices to identify themselves on a network (the MAC address)

• devices use ARP to communicate

• steps

  • ARP request asks all devices for the target address

  • ARP reply is when the target address device responds

  • the that IP is stored in the ARP cache

DHCP (dynamic host configuration protocol)

assigns temporary IP addresses

• DHCP discover: device sends request to its DHCP for an IP

• DHCP offer: DHCP server sends an option

• DHCP request: device accepts the option

• DHCP ACK: server acknowledges and sets the IP for 24 hrs