IIUSA – Internet Institute Switches & Routers IIUSA – Internet Institute Section Objectives...
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Transcript of IIUSA – Internet Institute Switches & Routers IIUSA – Internet Institute Section Objectives...
IIUSA – Internet Institute
Switches & Routers
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 TableNetwork A e0Network 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 172.16.0.0/24 is subnetted, 1 subnetsC 172.16.1.0 is directly connected, Ethernet0 10.0.0.0/24 is subnetted, 2 subnetsR 10.2.2.0 [120/1] via 10.1.1.2, 00:00:07, Serial2C 10.1.1.0 is directly connected, Serial2R 192.168.1.0/24 [120/2] via 10.1.1.2, 00:00:07, Serial2
Portion of aRouting 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 172.16.10.100
Network ID Host 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 L
ength 4
Type of S
ervice 8
Total L
ength 16
Identification 16
Flags 3
Fragm
ent Offset 13
Tim
e to Live 8
Protocol (U
pper Level) 8
Header C
hecksum 16
Source
IP A
ddress 32
Destination
IP A
ddress 32
IP O
ptions Variable
Data
Padding (If N
eeded)
IIUSA – Internet Institute
IP Address Numbering
• IP Addresses are 32 bits in length
172 16 122 204. . .Network Host
Each Octet is 8 bits in length, representing a byte
10101100 00010000 01111010 11001100
IIUSA – Internet Institute
Converting IP Addresses from Binary to Decimal
11 11 11 11 11 11 11 11
128128 6464 3232 1616 88 44 22 11
8 Bits
255 Decimal Value
Note: All 0s indicates a decimal 0, totaling 256 Decimal Values
IIUSA – Internet Institute
Conversion Example
11 00 11 11 00 11 00 11
128128 6464 3232 1616 88 44 22 11
8 Bits
255 Decimal Value
128+ 32+ 16+ 4+ 1 181
IIUSA – Internet Institute
IP Classes
H HHN
H HNN
N HNN
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)
H HHN
0
IIUSA – Internet Institute
Class B Notes
• Address range 128 to 191
• Address 172.16 to 172.31 is reserved as a private address range
• First two bits begin with a 10
H HNN
10
IIUSA – Internet Institute
Class C Notes
• Address range 192 to 223
• Address 192.168 is reserved as a private address range
• First three bits begin with a 110
N HNN
110
IIUSA – Internet Institute
Reserved Address Space
• 0s (zeros) in the host portion of the address space is reserved for the network numbernetwork number– Example: 172.16.0.0
• 1s in the host portion of the address is reserved for the broadcast addressbroadcast address– Example: 172.16.255.255
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 172.16.0.0
172.16.1.0 172.16.2.0
172.16.3.0
172.16.4.0
172.16.5.0
IIUSA – Internet Institute
16
Network Host
172 0 0
10101100
11111111
10101100
00010000
11111111
00010000
00000000
00000000
10100000
00000000
00000000
• Subnets not in use—the default
00000010
Subnet Mask without SubnetsSubnet Mask without Subnets
172.16.2.160172.16.2.160
255.255.0.0 255.255.0.0
NetworkNumber
Subnet Mask
IIUSA – Internet Institute
• Network number extended by eight bits
Subnet Mask with SubnetsSubnet Mask with Subnets
16
Network Host
172.16.2.160172.16.2.160
255.255.255.0 255.255.255.0
172 2 0
10101100
11111111
10101100
00010000
11111111
00010000
11111111
00000010
10100000
00000000
00000000
00000010
Subnet
NetworkNumber
128
192
224
240
248
252
254
255
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)
11
22
33
Example of Class B Address
Number of SubnetsNumber of Subnets
Binary ValueBinary Value
Convert to DecimalConvert to Decimal
6
0 0 0 0 0 1 1 0
= 6
(3 Bits)
4+2
255 . 255 . 224 . 0
11111111 11111111 11100000 00000000
Subnet MaskSubnet Mask
Ignore the first bit borrowed, add the additional bits borrowed to determine the number of new subnets
IIUSA – Internet Institute
Defining Subnet IDs
255 255 224 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0
00000000 = 000100000 = 3201000000 = 6401100000 = 9610000000 = 12810100000 = 16011000000 = 19211100000 = 224
11
22 33
Evaluate the bit patterns establishedwithin 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
1100000011000000
6464
0+ 64= 64+ 64= 128+ 64
192
w.x.64.1 w.x.127.254
w.x.128.1 w.x.191.254
11
22
33
IIUSA – Internet Institute
Defining Host IDs for a SubnetSubnet IDsSubnet IDs Host ID RangeHost ID Range
Invalidx.y.32.1 – x.y.63.254x.y.64.1 – x.y.95.254x.y.96.1 – x.y.127.254x.y.128.1 – x.y.159.254x.y.160.1 – x.y.191.254x.y.192.1 – x.y.223.254Invalid
Invalidx.y.32.1 – x.y.63.254x.y.64.1 – x.y.95.254x.y.96.1 – x.y.127.254x.y.128.1 – x.y.159.254x.y.160.1 – x.y.191.254x.y.192.1 – x.y.223.254Invalid
00000000 = 000100000 = 3201000000 = 6401100000 = 9610000000 = 12810100000 = 16011000000 = 19211100000 = 224
00000000 = 000100000 = 3201000000 = 6401100000 = 9610000000 = 12810100000 = 16011000000 = 19211100000 = 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
172.16.1.0 172.16.2.0
172.16.3.0
172.16.4.0
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
XY
AA
BB
CC
A B C
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 ProtocolsRouted Protocols – Any network protocol run on a workstation as a part of the network operating system that provides networking capabilities (Ex: TCP/IP)
Routing ProtocolsRouting 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
• All routing protocols utilize metricsmetrics 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 MemoryDRAM SIMM
Ethernet Serial
Con
sole
AU
XShared Memory
Fixed DRAM
System CodeFlash or PROM
Flash CardSlot
BootROMS
PolarizationNotch
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 0 - 4
TFTP Server
Modem Bank
Modem Bank
Dial-in Access with modems
NetworkManagement
Station
IIUSA – Internet Institute
Router and Switch Configuration