4 Addressing Working At A SmalltoMedium Business or

4: Addressing Working At A Small-to-Medium Business or ISP

Objectives • Plan an IP addressing scheme – Subnetting – Classful • IPv 6 classless routing • NAT & PAT

Addressing • Every device on a network MUST have an IP address! – IPv 4 • How many bits in an IP address? – 32 • What’s the maximum amount of bits in an octet? – 256 • Convert 192. 168. 1. 106 – 11000000. 10101000. 00000001. 01101010

Conversion Practice 1 • 11100101 to decimal • 10001110 to decimal • 11111000 to decimal • 1111 to decimal

Conversion Practice 2 • 192 to binary • 224 to binary • 47 to binary • 115 to binary

IP Address Review- Class A • Range: • Default Subnet Mask: • Which octets are Network & Host? • How many hosts available?

Convert A • 5 to binary • 77 to binary • 100 to binary • 127 to binary • What’s in common with all of them?

IP Address Review- Class B • Range: • Default Subnet Mask: • Which octets are Network & Host? • How many hosts available?

Convert B • 128 to binary • 142 to binary • 191 to binary • What’s in common here?

IP Address Review- Class C • Range: • Default Subnet Mask: • Which octets are Network & Host? • How many hosts available, total & useable?

Convert C • 192 to binary • 200 to binary • 223 to binary • What’s common here?

Subnet Masks • 255. 0 – How many total bits are on? (1’s) • 11111111. 0000 • /24 notation • 255. 0. 0 – How many total bits are on? (1’s) • 11111111. 0000 • /16 notation • 255. 248 – How many total bits are on? (1’s) • 11111111. 11111000 • /29 notation

Routers, IP’s & Subnet Masks • Router ONLY knows which NETWORKS it is connected to!!! • Doesn’t care about individual hosts • It ANDs the IP & Subnet Mask • Result= DESTINATION NETWORK

ANDing

Subnet- Split Up the IP • Borrow bits to make new networks • Plan your network – How many networks? – How many hosts per network?

Before we do this… • When we borrow, MUST borrow at least 2 bits or leave at least 2 bits – Class C has 1 octet to borrow from – Class B has 2 octets – Class A has 3 octets – – – 2 2= 4 2 3= 8 24= 16 25= 32 26= 64

199. 72. 101. 0

199. 72. 101. 0 1. 2. 3. 4. 5. 6. 7. 8. 199. 72. 101. 0 -31. 32 -. 63 (. 33 -. 62). 64 -. 95 (. 65 -. 94). 96 -. 127 (. 97 -. 126). 128 -. 159 (. 129 -. 158). 160 -. 191 (. 161 -. 190). 192 -. 223 (. 191 -. 222). 224 -. 255 • Total Range #3 – Useable Range #2 • Network ID – 199. 72. 101. 64 /27 • Broadcast Address – 199. 72. 101. 95 /27

Assign Addresses

Router…Action! • A packet with a destination IP of 199. 72. 101. 85 255. 224 goes to a router – It ANDs to come up with the NETWORK #

Keep It Private • Inside hosts have private IP – Only devices that connect directly to Internet have a public IP – Consumer ISR/Routers give out private addresses • What’s the Class A private? • B? • C?

Parts of the Network Hosts Subnetwork

How to Work Backwards • 221. 17. 125. 46 /28 – What class address? • C: Only deal with the last octet! – 255. 240 – 11111111. 11110000 – How many bits borrowed? • 4 • 24= 16 networks – How many bits left over? • 4 • 24= 16 hosts per sub-network

Work Backwards • Based on the IP address & SM, identify… – The network address – The broadcast address – How many bits were borrowed – How many bits were left over – Is the address valid

What’s Wrong? • Are the hosts on the same network or separate?

Questions • What’s the broadcast address for 201. 78. 90. 0 /24? – 201. 78. 90. 255 – Default SM, no subnetting • Sam’s Beef Hut uses network 215. 67. 106. 0 & 255. 240 to create subnets. How many useable hosts can be created per network? – 14

Questions • Which class gives you the most hosts/network? –A • Which class give you the most networks? –C • Public IP addresses must be _____.

Lab • 4. 1. 5

Classless Subnetting • CIDR • VLSM • You can subnet, for each unequal network – Your address is 210. 1. 17. 64 /26 • Net A needs 37 hosts • Net B needs 15 hosts • Net C needs 100 hosts

CIDR Block for Router • Instead of having multiple subnet entries for each router port, CIDR uses the common bits to make ONE routing table address per port.

Running Out of Addresses • Private Addresses • IPv 6 – 32 bits NOW 128 bits long! – 2128 which is 3 PLUS 38 ZEROs!

NAT • Network Address Translation • Allows many users to use private IP addresses inside & translates to a pool of public IP’s for travel outside • Purpose: – Save public IP addresses – So private IP computers could communicate on the Internet

NAT in Action!

What’s the Order of NAT? • Inside Local IP (Private) goes into your router • Translated to an Inside Global IP before exiting • Sent across Internet to Outside Local • Outside Global sends it back to the Inside Global • Your router translates the Inside Global back to the Inside Local (Private) IP

Activity

Static NAT • Static= stays the same • Same public IP address maps to a private internal one

Static NAT 2

Dynamic NAT • Has a pool of addresses • Translates the private IP to a public & awaits a response – After session is closed, the public IP is returned to the pool of addresses

Summary of NAT • Static NAT – Outside users need to access inside private network • At home, you need to access the mail server – Static private IP is given a static public address • Dynamic NAT – Inside private IP host needs to access the public Internet – Selects from a pool of addresses • Both can be configured at the same time

NAT Review • Static NAT works by mapping a specific inside local private IP address to what other specific address type? – Inside global – Outside local – Outside global – Private IP address

PAT (or NAT Overload) • Port Address Translation • Used when you have very few public IP addresses • Translates multiple IP’s into a single public – Uses port #’s to keep track of conversations – Uses random source port # above 1024

PAT Review • Which statement describes NAT overload or PAT? – Each internal address is dynamically translated to an individual external IP address. – A single internal address is always translated to the same external IP address. – Many internal addresses are translated to a single IP address using different port numbers. – Many internal addresses are statically assigned a single IP address and port.

PAT Review • Which port numbers are used by PAT to create unique global addresses? – 255 and below – 1024 and below – 1025 and above – 64, 000 and above

Lab • 4. 2. 4

Review

4: Addressing Working At A Small-to-Medium Business or ISP