Network Layer
- "Internetwork layer"
- Creating lots of different networks
- "Inter" - going through different routers and paths.
- Allows for creatin of networks of networks
- Internet Protocol beat others for dominance in this space (IPX, AppleTalk)
- Global Reachability
Routed Layer
- Layer 3 is the realm of packets
- Packets usually have global delivery
- Use a routing table to determine where each of our packages go
- Forwarding based on destination IP address
- Sometimes we create filtering decisions
- IP address can tell the geographic location "Geo IP"
Internet Protocol Version 4
- IPv4
- 32 bits
- 4.2 billion numbers = 2^32
- Exhaustion concerns in the 1990s
- Address
192.168.1.10
- Subnet mask
/24, 255.255.255.0
- A subnet mask lets us look at an IP address and say this is where it ends, and this is where it begins.
- In this case, everything that has "255" identifies our network.
- Ex: The network of the IP address
192.168.1.10 is 192.168.1 and the host is actually .10
- A subnet mask lets us find network bits and host bits.
- Gateway
192.168.1.1
- Every network needs it, it lets us know who is IN the network and who is remote
- In other words this is the "Exit" to get to other networks.
- Ex: If you wanted to reach the IP
4.2.2.2, you look at your subnet mask and you will say "that's not on my network" so it will be send that data to the gateway.
- Typically Identifies a Router
- Addressing is often private and non-hierarchical
- These values will be transferred into public values when going out onto the internet
Internet Protocol Version 6
- IPv6
- They run out of IPv4 addresses
- 128 bits
- Intergalactic addressing capability
- Hierarchical routing
- Globally Unique Identifier
- Address format is
2620:0:1:cfe:face:b00c::3
/64 is common mask FFFF:FFFF:FFFF:FFFF::0- IPv6 is typically preferred over IPv4 by your operating system