IP

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• Chapter 10

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IP

• Packet-switching
• Connectionless
• Unreliable
• Best-effort delivery
• Depends on TCP to provide error checking and
  reliability

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Benefits of Subnetting

• Creates smaller broadcast domains
• Provides low-level security
• Increases address flexibility

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Layer 3 Device

• Router
• provides end-to-end packet delivery services to
  its user, the transport layer
• Makes best path determination based on IP
  addressing
• Strips off Layer 2 source addresses and replace
  them with its OWN Layer 2 source address when
  forwarding a packet.

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Routers

• Do not forward broadcast or multicast frames
• Forward packets based on the Layer 3 header
  information.
• Can limit or secure network traffic based on
  identifiable attributes within each packet.
• Switch packets to the appropriate interface based
  on the destination IP address.
• Can perform bridging and routing.

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Layer 3 Packet/Datagram
Prevents routing loops
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Layer 3 Devices

• Routers
• Interconnect network segments or entire networks.
• Make logical decisions based on IP addresses.
• Determines best path for data on an internetwork.
• Create broadcast domains

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Path Determination

• The process the router uses to choose the next
  hop in the path the packet travels.
• The router uses the network address to identify
  the destination network of a packet within an
  internetwork.
• IP addresses can be assigned by a network
  administrator or automatically (dynamically.)

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Broadcast Addresses

• Broadcast Address is used to send data to all
  of the devices on a network.
• Broadcast IP addresses end with binary 1s in the
  host part of the address.
• Class B Broadcast Address example
• 176.10.255.255
• (Remember decimal 255 binary 11111111)

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BINARY ANDING

• This is the process that routers use to determine
  the network or subnetwork portion of an IP
  address using the address and the subnet mask
• Both digits must be ones in order for the result
  to be a one.

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Layer 3 Protocols

• IP
• Internet Protocol
• ARP
• Address Resolution Protocol
• ICMP
• Internet Control Message Protocol

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DHCP Process

• Requires DHCP server on network
• Initializes on computer start-up
• Sends DHCP discover
• Server responds with a DHCP offer
• Host responds with a DHCP request
• Server responds with DHCP ack

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Default Gateway

• A default gateway is the IP address of the
  interface on the router that connects to the
  network segment that it needs.
• The default gateways IP address must be in the
  same network segment as the host is on.

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Routed Protocols

• Provide packet switching and packet forwarding
  between hosts (end system to end system)
• Bases decisions on logical addresses
• Examples
• IP
• IPX
• Appletalk
• XNS
• DECnet

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NetBEUI

• Non-routable layer 3 protocol
• Small, fast, efficient
• Only works on the same network segment

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Router Interfaces

• Routers connect separate networks
• Each of the connections to those network is
  called interface or port
• Each interface must have its own IP address

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Routing Protocol

• Maintains a routing table
• Table of routes to network destinations and
  metrics to those destinations
• Shares routing tables between
• Routing tables include
• Protocol(s) used
• Metrics
• Networks
• Outbound interfaces
• Examples
• RIP (Routing Information Protocol) distance
  vector
• IGRP (Interior Gateway Routing Protocol)
  distance vector
• OSPF (Open Shortest Path First) link state
• EIGRP (Enhanced IGRP) - hybrid
• IS-IS (Intermediate System to Intermediate
  System) link state

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Metric

• A measurement
• Used by routing protocols to determine the best
  path to a destination
• Examples
• RIP hop count
• IGRP bandwidth, load, reliability, delay

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Routed vs. Routing Protocols

• Routed protocols are routed by routing protocols.

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RIP

• Distance vector routing protocol
• Metric hop count
• Max 15 hops
• Routing table updates every 30 seconds