2/6/2024 - Routing and Routing Protocols

Routers

• Computers that transfer packets between different networks (IP)
• Post office analogy - zip codes
• Routers are part of layer 3 of the OSI model, makes decisions using info from IP address in packet
• Builds a table of Network IDs and IP of the next router in that direction
• Inspects packets for NetID of Ip address and sends the packet to the next router
• Doesn't need to know a whole path, just where the next router in the path is

Switches

• Layer 2 of OSI model
• Monitor MAC addresses in a LAN and the port they use
• Forwards packets to the right port using MAC address

Routing Table necessities:

• Network Address
• Subnet Mask - Subnet mask for that network, so it knows how many bits are in a NetID
• Next Hop - Next router in the path neighboring current router
• Interface - Which of the routers own physical interfaces which it can send the packet out of to reach the Next hop
• Other data includes distance (how many hops to the network) and preference if there are more than one entries for the same route

2/13/2024 - all the quiz answers

• 48 bits in a MAC address (12 hex characters)
• MAC address is built into the NIC (network interface controller)
• Hubs go to museum, switch with a switch
• ARP begins by checking ARP cache, determine is local or distant, send to router etc
• tracert used for tracing the route to a destination using ICMP
• OSI layer 3 - physical address, routers, IP address

2/20/2024

• Subnet Masks indicate how many bits are used for a Network, and how many bits are used for the Host.

• Network address goes into router, broadcast address is used

2/23/2024

• IPs are expensive. Be stingy with em
• Most routing bone in 255.255.x.x area
• 32 bit jasndlfknsaea Binary
• 128 64 32 16 8 4 2 1
• 1 1 1 1 1 1 0 0
• 242? no 252

2/27/2024

• If you need 31 hosts, don't use network with 30 hosts
• 10.x.x.x Private Address
• Not routable through internet
• 172.(16-31).x.x Also Private
• 192.168.x.x

CIDR Subnet Addr 1st Last Broadcast

/22 7.8.0.0 7.8.0.1 7.8.3.254 7.8.3.255

/23 7.8.4.0 7.8.4.1 7.8.5.254 7.8.3.255

/22 7.8.6.0 7.8.6.1 7.8.7.254 7.8.7.255

/26 7.8.8.0 7.8.8.1 7.8.8.62 7.8.8.63

/26 7.8.8.64 7.8.8.65 7.8.8.126 7.8.8.127

   7.8.8.128

• Switch goes to cloud
• Static Routing -it sucks
• RIP

3/26/2024

IGP - Interior Gateway Protocol EGP - Exterior Gateway Protocol

4/2/2024

Access vs Trunk Port

• Access is for end devices, can be assigned only one VLAN
• Trunk is between two switches, allows for VLANs to san across multiple switches
  • "tag" packets with VLAN ID

CISCO IOS Tips

• Up arrow for last command
• ? for help menu
• TAB for autocomplete command
• exit to go "up" a level
• show run (do show run in config mode) to view config file
• no (IP address) to delete IP from interface

4/5/2024

4/9/2024

• Wireless VS Wired Connections
• Wireless has methods for "handing off" connection, easier network expansion, easier setup, and is cheaper
• ieee802.org