User:Itpastorn/dko/ccna1-3.1-10

From Wikipedia, the free encyclopedia

Module 10 Routing Fundamentals and Subnets

Contents

Overview CCNA 1 - Module 10 (3.1)

[edit] Routed Protocol

[edit] Routable and routed protocols

Examples of routable protocols

[edit] IP as a routed protocol

[edit] Packet propagation and switching within a router

[edit] Connectionless and connection-oriented delivery

  • Packet propagation within a router

[edit] Anatomy of an IP packet

  • Anatomy of an IPv4 packet
  • Anatomy of an IPv6 packet

[edit] Routing Protocols

  • Provides processes used to share route information
  • Allows routers to communicate with other routers to update and maintain the routing tables

[edit] Routing overview

"A router is a network layer device that uses one or more routing metrics to determine the optimal path along which network traffic should be forwarded."

Non-routable protocols have no layer 3 functionality. E.g. NetBEUI.

[edit] Routing vz Switching

Layer 3 vz. layer 2 (long distance vz. local calls)

Both have:

  • ARP-tables

The switch:

  • Uses MAC-addresses
  • Has CAM-tables
  • Forwards broadcasts

The router:

  • Uses IP-addresses
  • Has routing tables
  • Blocks broadcasts

[edit] Routed vz. Routing

[edit] Path determination

  • Compares the IP address of the packet to the IP tables
    • Obtained destination address from the packet.
    • Apply mask of first entry and compare
    • Forward if its a match
    • Otherwise repeat process for next entry in the table
  • No match at all?
    • Default route?
    • Yes. Use it!
  • No default route? The packet is discarded. (Perhaps) tell sender that destination is unreachable.

[edit] Routing tables

"A hierarchical address scheme is required for data transfers."

  • Protocol type
  • Next-hop associations
  • Routing metric
  • Outbound interfaces

[edit] Routing algorithms and metrics

Design goals:

  • Optimization – "Select the best route" based on metrics.
  • Simplicity and low overhead – Simple algorithm = easy to process
  • Robustness and stability – can handle unusual or unforeseen circumstances
  • Flexibility – Adapt quickly to a changes
  • Rapid convergence - all routers should "agree" quickly

routing metrics

  • Bandwidth
  • Delay
  • Load
  • Reliability
  • Hop count
  • Ticks (Approximately 1/18 second)
  • Cost

[edit] IGP and EGP

  • IGP:
    • RIP
    • RIPv2
    • IGRP
    • EIGRP
    • OSPF
    • Intermediate System-to-Intermediate System (IS-IS) protocol
  • EGP:

[edit] Link state and distance vector

[edit] Routing protocols

[edit] Mechanics of subnetting

[edit] Classes of network IP addresses

A-class B-class C-class D-class
8 network bits 24 host bits 16 network bits 16 host bits 24 network bits 8 host bits 32 host bits
16.7 million hots 65 534 hosts 254 hosts (used exclusively for multicasting groups)

[edit] Introduction to and reason for subnetting

  • Manageability
  • Broadcast containment
  • Low-level security (routers as firewalls between subnets)

Subnets are not seen from outside. Traffic to all subnets may be directed to the net as a whole.

[edit] Establishing the subnet mask address

IPv4 subnetting reference

  • Number of usable host addresses
    • Requirement of the largest subnet

[edit] Applying the subnet mask

  • Classic (dotted) notation
  • CIDR notation

[edit] Subnetting Class A and B networks

[edit] Calculating the resident subnetwork through ANDing

[edit] Extra topics (in addition to CCNA)

[edit] Additional resorces (besides Wikipedia)

[edit] Navigation