Planning the Addressing Structure Working at a Small-to-Medium Business or ISP – Chapter 4
Implementation of IP Addressing in the LAN IP addresses are made up of 32 total bits divided into 4 octets with a decimal separating them AKA: dotted decimal notation
IP Address and Binary Review In an 8 bit binary number, what is the total number of combinations of the eight bits? 256 combinations = 28 Convert 230 into binary.
IP Addressing IP addresses are HIERARCHIAL (like a family tree) there are parents (networks) there are children (hosts)
IP Address Classes Classes A – C Class D – reserved for multicasts assigned to users Class D – reserved for multicasts Class E -- reserved for experimental use
IP Address Classes Classful IP Addresses The number of bits used to identify the hosts is fixed by the class of the network All subnets in a network are the same size.
Private & Public IP Addressing Public Addressing - Public IP addresses must be unique across the entire Internet. Private IP addresses assigned by IETF (Internet Engineering Task Force) reduces the number of public IP addresses assigned to organizations
Implementation of IP Addressing in the LAN SUBNETS
Lets Learn How To Subnet Subnet – Take a network address and break it apart to better fit your network setup and structure. Subnet Help Sheets Are Your Friend
IP Addressing Practice Class C address with a default subnet mask. Question 1 – What is the default subnet mask 255.255.255.0 Question 2 – How many usable hosts are available? 254 IPv4 Question 1 – Class which provides the largest number of network bits?
IP Addressing Practice Class B address Question 1 – What is the default subnet mask 255.255.0.0 Question 2 – The IP address is 155.14.0.0 with a default subnet mask. What is the broadcast address for this network? – Change all Host bits to 255. 155.14.255.255 IPv4 Question 1 – The IP address is 192.168.4.0 with a subnet mask of 255.255.255.224. What is the maximum number of sub networks that could be created. 6 networks Question 2 – The IP address is 192.133.219.0/27. What is the first usable host address in the first usable range? 192.133.219.33 Class C Question 2 – Class which provides the largest number of hosts per network? Class A
Subnet Question Refer to the exhibit. Which range of IP addresses would allow hosts that are connected to the Router1 Fa0/0 interface to access outside networks? 192.168.1.66 through 192.168.1.94
Subnet Question Refer to the exhibit. Host A is connected to the LAN, but it cannot get access to any resources on the Internet. The configuration of the host is shown in the exhibit. What could be the cause of the problem? The default gateway is on a different subnet from the host.
IP Versions IPv4 IPv6 32 bits Separated by a period 133.15.6.4 Separated by colons More address space Better address mgmt
Using Network Address Translation in a Network (NAT) Allows a large group of private users to access the Internet by sharing a small group of public IPs comparable to a company with a few phone lines, but many extensions Developed to help save registered IP addresses Provides security to PCs, servers, devices, etc
Advantages & Disadvantages of NAT Reuse of IP addresses Sharing of a global IP address Security Scalability Router CPU load Poor network performance Remote access may be denied if trying to access a server with a private IP
NAT Terminology Inside local network Outside global network any network connected to a router interface that is part of the privately addressed LAN Outside global network any network attached to a router that is external to the LAN
More NAT Terminology Inside local address Outside global address Private IP address of a host on the local network Must be translated to a public IP before it can travel outside Outside global address Actual public IP address of an external host
More NAT Terminology Inside global address Outside local address IP address of inside host as it APPEARS to the outside network Outside local address Destination address of packet while on the local network Usually the same as outside global address
Question What must happen for a privately addressed host on an inside local network to be able to communicate with an outside destination host on the Internet? The host IP address must be translated to an inside global address.
Static NAT Provides access to a local host from the Internet Allows hosts on public network to access selected hosts on a private network Static NAT works by mapping a specific inside local IP address to what other specific address type? inside global
Static NAT Example The host with the IP address of 192.168.32.10 will always translate to 213.18.123.110.
Dynamic NAT Maps an unregistered IP address to a registered IP address from a group of registered IP addresses. The host with the IP address of 192.168.32.10 will translate to the first available address in the range of 213.18.123.10 to 213.18.123.150
PAT (NAT Overload) Many internal addresses can be translated to a single IP address using different port assignments Each computer on the private network is translated to the same IP address (213.18.123.100), but with a different port number assignment. Outside users are unable to initiate communication to a host if using PAT
PAT (Overloading) Uses unique source port numbers in the inside global IP address Uses first available port number PAT uses port numbers must be above 1024
NAT Question Refer to the exhibit. R1 is performing NAT for the 10.1.1.0/24 inside network. HostA has sent a request to the web server. What is the destination IP address of the return packet from the web server? 172.30.20.10
Summary IP addressing can be tailored to the needs of the network design through the use of custom subnet masks. Classless subnetting gives classful IP addressing schemes more flexibility through the use of variable length subnet masks. Network Address Translation (NAT) is a way to shield private addresses from outside users. Port Address Translation (PAT) translates multiple local addresses to a single global IP address, maximizing the use of both private and public IP addresses.