IIUSA – Internet Institute Switches & Routers Rick Livingood, MA, MCSE, CCNP IIUSA – Internet Institute

Section Objectives Overview of Switches and Routers in a Network Environment Switch Configuration Routing Basics and Configuration Displaying Router Information Troubleshooting Routers and Switches

IIUSA – Internet Institute Layer 3 (IP) Basics Provides ability to address devices with a logical address and route traffic not locally attached –Logical addresses are applied to source and destination nodes or devices –Paths are determined to forward data from a local device to a remote device on another network

IIUSA – Internet Institute Router Functionality Network A Network B Routing Table Network A e0 Network B e1 e0 e1 Routers Separate Broadcast Domains

IIUSA – Internet Institute Why a Logical Address Hierarchical addresses provide reachability across boundaries called subnets Similar to the phone system with area codes to differentiate geographical regions or zip codes to indicate different cities and towns A hierarchical logical computer address contains a network identifier and host or unit identifier

IIUSA – Internet Institute Network Segments The size of a network dictates traffic load and potential for overload As growth overwhelms a network (similar to cars crowding a highway), segments can be created to off load traffic Each new segment is autonomous of other network segments Without segmentation, all addressing would be done through a flat addressing scheme (MAC addressing) overwhelming segmentation discovery devices (routers)

IIUSA – Internet Institute Connectivity Between Segments Segments can communicate through devices that determine a path from one network to another over communications lines Devices (routers) can determine the best path in the case of multiple paths Paths or routes are stored in routing tables /24 is subnetted, 1 subnets C is directly connected, Ethernet /24 is subnetted, 2 subnets R [120/1] via , 00:00:07, Serial2 C is directly connected, Serial2 R /24 [120/2] via , 00:00:07, Serial2 Portion of a Routing Table

IIUSA – Internet Institute Network Layer Addressing Routers use a portion of the address to determination Network identification All hosts or devices within a given network segment are identified by a host portion of the address IP Addresses Network IDHost ID

IIUSA – Internet Institute Path Determination Network layer determines BEST path from source to destination A router examines reported paths over links, determining best path from metrics associated with each path Best Path

IIUSA – Internet Institute IP Header Detail Data Version 4 Header Length 4 Type of Service 8 Total Length 16 Identification 16 Flags 3 Fragment Offset 13 Time to Live 8 Protocol (Upper Level) 8 Header Checksum 16 SourceIP Address 32 DestinationIP Address 32 IP Options Variable Data Padding (If Needed)

IIUSA – Internet Institute IP Address Numbering IP Addresses are 32 bits in length NetworkHost Each Octet is 8 bits in length, representing a byte

IIUSA – Internet Institute Converting IP Addresses from Binary to Decimal Bits 255 Decimal Value Note: All 0s indicates a decimal 0, totaling 256 Decimal Values

IIUSA – Internet Institute Conversion Example Bits 255 Decimal Value

IIUSA – Internet Institute IP Classes HHHNHHNNNHNN Class A Class B Class C - Network numbers are assigned by ARIN - Host numbers assigned by Network Administrators

IIUSA – Internet Institute Class A Notes Address range 1 to 126 Address 10 is reserved as a private address Address 127 is reserved for loopback purposes First bit begins with a 0 (zero) HHHN 0

IIUSA – Internet Institute Class B Notes Address range 128 to 191 Address to is reserved as a private address range First two bits begin with a 10 HHNN 10

IIUSA – Internet Institute Class C Notes Address range 192 to 223 Address is reserved as a private address range First three bits begin with a 110 NHNN 110

IIUSA – Internet Institute Reserved Address Space network number0s (zeros) in the host portion of the address space is reserved for the network number –Example: broadcast address1s in the host portion of the address is reserved for the broadcast address –Example:

IIUSA – Internet Institute A Case for Subnetting The original IP addressing scheme was sufficient for the early days of the internetworking environment As the Internet grew in the 1990s, addressing, using classful addressing became impractical Subnetting (classless) addressing became the answer for address space depletion

IIUSA – Internet Institute Subnetting Subnetting borrows host bits to increase the number of networks The number of hosts is reduced in proportion to the number of bits borrowed

IIUSA – Internet Institute A Subnetted Network Original Network

IIUSA – Internet Institute 16 Network Host Subnets not in use—the default Subnet Mask without Subnets Network Number Subnet Mask

IIUSA – Internet Institute Network number extended by eight bits Subnet Mask with Subnets 16 Network Host Subnet Network Number

IIUSA – Internet Institute Defining a Subnet Mask Convert the Number of Segments to Binary Count the Number of Required Bits Convert the Required Number of Bits to Decimal (High Order) Example of Class B Address Number of Subnets Binary Value Convert to Decimal = 6 (3 Bits) Subnet Mask Ignore the first bit borrowed, add the additional bits borrowed to determine the number of new subnets

IIUSA – Internet Institute Defining Subnet IDs = = = = = = = = Evaluate the bit patterns established within the subnetted region

IIUSA – Internet Institute Shortcut to Defining Subnet IDs List the Number of Bits (High Order) Used for Subnet Mask Convert the Bit with the Lowest Value to Decimal Increment the Value for Each Bit Combination = = w.x.64.1w.x w.x.128.1w.x

IIUSA – Internet Institute Defining Host IDs for a Subnet Subnet IDs Host ID Range Invalid x.y.32.1 – x.y x.y.64.1 – x.y x.y.96.1 – x.y x.y – x.y x.y – x.y x.y – x.y Invalid x.y.32.1 – x.y x.y.64.1 – x.y x.y.96.1 – x.y x.y – x.y x.y – x.y x.y – x.y Invalid = = = = = = = = = = = = = = = = 224 Each Subnet ID Indicates the Beginning Value in a Host Range The Ending Value Is One Less Than the Beginning Value of the Next Subnet ID

IIUSA – Internet Institute Network to Network Connectivity  Router strips off the data link header  Examines the network layer address  Consults the routing table to find the interface for the network 1 2 3

IIUSA – Internet Institute Network-Layer Protocol Operations Each router provides its services to support upper-layer functions X Y A B C ABC Physical Data Link Network Physical Data Link Network Physical Data Link Network Physical Data Link Network Transport Session Presentation Application Physical Data Link Network Transport Session Presentation Application

IIUSA – Internet Institute Routed Versus Routing Protocols  Routed Protocols  Routed Protocols – Any network protocol run on a workstation as a part of the network operating system that provides networking capabilities (Ex: TCP/IP)  Routing Protocols  Routing Protocols – Protocols run on a router to provide the ability for the router to share path information (Ex: RIP, IGRP)

IIUSA – Internet Institute Routing Protocols Interior Routing ProtocolsInterior Routing Protocols – support the sharing of routes or paths within the internal internetwork (Ex: RIP, IGRP, EIGRP, OSPF) Exterior Routing ProtocolsExterior Routing Protocols – support the sharing of routes or paths across large internetworks, such as the Internet (Ex: BGP and EGP)

IIUSA – Internet Institute Routing Metrics metricsAll routing protocols utilize metrics to characterize best path information –Hop Count –Bandwidth –Delay –Load –Reliability –Ticks (Novell) –Cost – generic definition of metric information

IIUSA – Internet Institute Static versus Dynamic Routes StaticStatic routes are established by a network administrator and manually input directly into the routing table DynamicDynamic routes are learned through the use of a Routing Protocol. Dynamic routes are adaptive. Changes to path availability or establishment of new paths are automatically shared with other routers

IIUSA – Internet Institute Routers A Router is a computer, with similar functionality Forwards packets, from incoming interface to outgoing interfaced, based on best path as determined by routes available in the routers Routing Table Segments a LAN into separate Broadcast Domains Must be used when connecting LANs across wide area network environment

IIUSA – Internet Institute Typical Router System Board Layout Primary Memory DRAM SIMM EthernetSerial ConsoleAUX Shared Memory Fixed DRAM System Code Flash or PROM Flash Card Slot Boot ROMS Polarization Notch Memory Types: RAM/DRAM NVRAM Flash Memory ROM

IIUSA – Internet Institute Typical Cisco Motherboard for a 2500 Series

IIUSA – Internet Institute Sources For Configuring Console Port Auxiliary Port Interfaces VTY TFTP Server Dial-in Access with modems Network Management Station

IIUSA – Internet Institute Router and Switch Configuration