ECE366 - Lesson 13
Networking Foundations
Instructor: Professor Hong
## Networking Foundations
## IP (Internet Protocol) Address
- Network location
- Host identification number
- Address of your computer
- 32 bits
- Dotted decimal notation
- e.g. 192.168.0.1
- e.g. 11000000 10101000 00000000 00000001
## Subnet Mask
- Indicates the host portion of the IP address
- e.g. 255.255.255.0
- IP address: 192.168.0.110
- Subnet Mask: 255.255.255.0
- Network: 192.168.0
- Host Identifier: 110
## Default Gateway
- Routes local router to remote destination IP address
- e.g. 192.168.0.1
## DNS Address
- Domain Name System
- Resolves website name into routable IP address
- www.linked.com -> 13.107.42.14
- 8.8.8.8, 8.8.4.4 - Google DNS servers
## Trying Things Out
```
ipconfig /all
ping 127.0.0.1 (internal loopback)
ping (defaultGatewayIpAddress)
ping (dnsServer; located in internet)
ping www.google.com
```
Example Network
Example Network
## Class A
- Range: 0.0.0.0 to 127.255.255.255
- High-order bits: 0
- Networks: 128
- Hosts: Approximately 16 million hosts
- Huge networks
## Class B
- Range: 128.0.0.0 to 191.255.255.255
- High-order bits: 10
- Networks: 16,384
- Hosts: 65,536
- Medium networks
## Class C
- Range: 192.0.0.0 to 223.255.255.255
- High-order bits: 110
- Networks: 2,097,152
- Hosts: 256
- Small networks
## Class D
- Range: 224.0.0.0 to 239.255.255.255
- High-order bits: 1110
- Multicast - sending data to a group of receivers addressed in a multiclass range
## Class E
- Range: 240.0.0.0 to 255.255.255.254
- High-order bits: 1111
- Experimental purposes
## Subnet Mask
The tool that permits the identification of the network ID portion of the IP address
- IPv4 Environments
- Opt for shorthand representation of subnet mask
- Type forward slash and number of bits
- Called prefix notation
- IPv6 Environments
- Uses only the prefix notation
## Examples
- 255.0.0.0 -> /8
- 255.255.0.0 -> /16
- 255.255.255.0 -> /24
## How a computer uses a subnet mask?
1. Communicates with a remote IP address
2. Uses your subnet mask
3. Uses your IP address
4. Determines network ID
5. Takes your subnet mask
6. Compares to the remote IP address
7. Discovers different network
8. Sends packet to default network
## IPv6 Address
- 128 bits in length
- Represented in hexidecimal
- Default mask is 64 bits
- Prefix notation
- Most computers have Dual-Stack Configuration (using IPv4 and IPv6 simultaneously)
## Shortening IPv6 Addresses
Two modifications
- Once in an address, can replace 0000:0000 with ::
- Trim off any leading 0’s from address
Example
- 2001:0db8:85a3:0000:0000:8a2e:0370:7334/64
- 2001:db8:85a3::8a2e:370:7334/64
## Problems
- Public IP address were in short supply
- The 32-bit address started looking inadequate
- Solved with IPv6
- Routing table size was growing
## Classless Inter-Domain Routing (CIDR)
- Corrects
- IP Address shortage issue
- Size of Internet routing table
- Ended the classful system of IP Addressing
- Conceptualized prefix notation
- Easier for ISP to allocate public IP address
## Route aggregation / Route summarization
- Use a subnet mask that’s shorter to summarize a large group of systems; making the subnet mask shorter
- Make routing tables smaller and more efficient
## Example
172.16.1.0/24
172.16.2.0/24
172.16.3.0/24
172.16.4.0/24
172.16.5.0/24
172.16.6.0/24
Mask off all of them in common
172.16.1.0/21 - proper summary (8+8+5 bits)
## Dynamic Host Configuration Protocol (DHCP)
- opular method of assigning IP addresses
- Uses client server concept
- Client joins network and broadcasts for DHCP server and gives required info
- IP address
- Subnet mask
- Default gateway
- DNS server addresses
## DORA Process
- Client broadcasts DHCP DISCOVER
- Server responds with DHCP OFFER
- Client responds with DHCP REQUEST
- Server responds with DHCP ACK
## Leases
- Lease has a duration
- Client can attempt to renew lease
- Server can allow leases to expire
- Server pulls address from the DHCP pool
## DNS Servers
- Located all over the world
- Preconfigured to cooperate with each other
- Can fwd to other servers
- Functions as a kind of database server
- Stored records are defined in a DNS zone
## Types of DNS Records
- A records resolve to IPv4 addresses
- AAA records resolve to IPv6 addresses
- MX records resolve to email addresses
## Setting Up DNS
- Can use cloud services (e.g. Amazon Route 53)
- Set your domain to go to your IP address
## RFC 1918
- Request for Comments, number 1918
- IP addresses for private networks
- Can have duplicates in different private networks, but not public
## NAT
- Network Address Translation
- translate private addresses into public IPv4 addresses
- In most cases, it can be configured automatically when renumbering the network