Objective 7 --> Routing

Broadcast

• A device that sends a broadcast out, and all other devices receive the broadcast

• Routers do not forward broadcasts

Inter VLAN Routing

• Routers enable a VLAN to communicate with other VLANs

Multi-Layer Switch (Layer 3 Switch)

• Performs layer 2 frame switching and layer 3 packet IP routing

• This eliminates the need for an additional router

Inter-VLAN communication

• Devices in a VLAN need to be in the same subnet

• Devices in different VLANs need to be in different subnets

• If a VLAN does not have a NID, it will not be able to forward to other VLANs

Default Gateway

• The path devices use to access other networks when no other routes are specified

• Can be configured by an admin or learned dynamically through the router

MAC Address vs IP Address

• MAC —> local delivery

• IP —> end-to-end delivey

Routing Protocol

• Dynamically find all networks to find the best path available

  • RIP, OSPF, EIGRP

Routed Protocols

• Assigned to an interface and determine the method of packet delivery

  • IPv4 and IPv6

Static Routing

• Manually configured by an admin

• Best for complete control

• Simplest form of routing

• Good for small networks

• Bad for large networks

• Unable to adapt to topology changes

Dynamic Routing

• Protocols learn their own tables (RIP, OSPF, EIFRP, etc.)

• Use metrics to determine a cost

• Good for large networks

• Can load balance between multiple paths

• Quickly adapts to toplogy changes

Administrative Distance (AD)

• Determines how reliable a route is

• Selects an IP method and protocol

• The lower the AD, the more trust it has

  • Manually entered routes > dynamically learned routes

  • Sophisticated metrics > simplistic metrics

Distance Vector Routing (RIP, IGRP)

• Each router provides a copy of its routing table

• Sends its neighbors two pieces of info —> how far, and where to go

Link State (OSPF)

• Provides toplolgy info to routers

• Each router shares info about its connections (links) and their status (state)

• The info is flooded to other routers and they build a map of the netwrok

• The shortest path is then determined

Balanced Hybrid (EIGRP)

• Sends route info only when a change occurs

Interior Routing Protocols

• Protocols used to route traffic within a single autonomous system (AS)

  • RIP, IGRP, OSPF, EIGRP

Exterior Routing Protocols

• Protocols used to route traffic between different autonomous systems

  • BGP