ARKnet Technical Training1 February 20, 1997 ARKnet Technical Training TCP/IP Fundamentals February 20, 1997

ARKnet Technical Training2 February 20, 1997 Presenter v David Merrifield - University of Arkansas –Associate Director Technical Services –ARKnet Network Manager –(501) –

ARKnet Technical Training3 February 20, 1997 Table of Contents v IP Addressing v Address Resolution v Routing Basics v Domain Name System v Troubleshooting IP Problems v Proteon Router

ARKnet Technical Training4 February 20, 1997 TCP/IP History v ARPA Project v ARPANET Created v MILNET Created v Berkeley Unix Integration v NSFNET Created v MIDNET Created v ARKnet Created v Internet2 Created

ARKnet Technical Training5 February 20, 1997 Components of TCP/IP Network v Devices v Network Media –Wide Area –Local Area v Networking Software

ARKnet Technical Training6 February 20, 1997 TCP/IP Network - Devices Workstations File Servers Printers Routers Coke Machines Coke

ARKnet Technical Training7 February 20, 1997 TCP/IP Network - Media Coke

ARKnet Technical Training8 February 20, 1997 TCP/IP Network - Software ISO Model

ARKnet Technical Training9 February 20, 1997 TCP/IP Network - Software TCP/IP Model

ARKnet Technical Training10 February 20, 1997 TCP/IP Network - Software

ARKnet Technical Training11 February 20, 1997 TCP/IP Layers in Work Host A Host B Application Transport Application Internet Network Interface Network Interface Internet Physical Net

ARKnet Technical Training12 February 20, 1997 Network Interface Address v Unique Address Per Interface v Assigned by Manufacturer (usually) v Common Names –Data Link Address –Link Address –Physical Address –Ethernet Address –Layer 2 Address

ARKnet Technical Training13 February 20, 1997 Network Interface Address v Typically 6-bytes long v Typical ethernet address: –00:00:c0:06:a3:08 Manufacturer Code (Western Digital) Unique Interface Number

ARKnet Technical Training14 February 20, 1997 Network Interface Address 00:00:0c:06:a3:08

ARKnet Technical Training15 February 20, 1997 Network Interface Address 00:00:0c:06:a3:08 Frame Source 00:00:0c:06:a3:08 Destination 00:00:0c:04:b1:74

ARKnet Technical Training16 February 20, 1997 Network Interface Address 00:00:0c:06:a3:08 Source 00:00:0c:04:b1:74 Destination 00:00:0c:06:a3:08 Frame

ARKnet Technical Training17 February 20, 1997 Network Interface Address 00:00:0c:06:a3:08 Frame Source 00:00:0c:04:b1:74 Destination 00:00:0c:06:a3:08

ARKnet Technical Training18 February 20, 1997 Network Interface Address v Network Interface Selects Frames –Destination Address Matches NIC –Destination Address is 00:00:00:00:00:00 u Broadcast Address –Any Address if in Promiscuous Mode v Network Interface Address Used by Data Link and Physical Layers

ARKnet Technical Training19 February 20, 1997 TCP/IP Network - Software

ARKnet Technical Training20 February 20, 1997 TCP/IP Layers in Work Host A Host B Application Transport Application Internet Network Interface Network Interface Network Interface Internet Router Physical Net 1Physical Net 2

ARKnet Technical Training21 February 20, 1997 Layer 3 - Internet Protocol v IP Layer Function –Data Delivery –Data Fragmentation v Addressing –Each Node Has Unique Address –32-Bit Address

ARKnet Technical Training22 February 20, 1997 IP Address - Format v 32-Bit Address (Four Octets) – : : : – 82 : b8 : 02 : 6c v Dotted Decimal Representation –

ARKnet Technical Training23 February 20, 1997 IP Addressing

ARKnet Technical Training24 February 20, 1997 Data Link & IP Addresses

ARKnet Technical Training25 February 20, 1997 IP Address v 32 Bits / 4 Octets Long v Authorized vs. Non-authorized v Network ID / Host ID v Address Classes v Subnetting

ARKnet Technical Training26 February 20, 1997 IP Address Authorization v InterNIC Registration v Use only NIC-authorized addresses for any Internet-connected network v ARKnet NOC supplies addresses from NIC-authorized address range v Larger networks may need to apply for CIDR block

ARKnet Technical Training27 February 20, 1997 IP Address v Network ID –Identifies Physical Network v Host ID –Identifies Individual Host Network ID Host ID

ARKnet Technical Training28 February 20, 1997 IP Address Classes Class A Class B Class C Class D Class E Net ID (7) Host ID (24) Net ID (14) Host ID (16) Net ID (21) Host ID (8) Multicast Address (28) Reserved

ARKnet Technical Training29 February 20, 1997 IP Address Classes

ARKnet Technical Training30 February 20, 1997 IP Address Space Crunch v Limited Address Space v Huge Internet Growth v Limited Capacity of Backbone Routers v Subnet Addressing v CIDR Introduced –Classless Inter-Domain Routing v IPv4 vs. IPv6

ARKnet Technical Training31 February 20, 1997 IP Addressing - Subnets v Subnetting Makes Better Use of IP Address Space –Class A & Class B Permit More Hosts Than Possible On Single Physical Net –Divides Address Space Into Multiple Class C Spaces –Utilizes Subnet Mask

ARKnet Technical Training32 February 20, 1997 IP Addressing - Subnets xxx.xxx Net IDHost ID Subnet Number Host Number

ARKnet Technical Training33 February 20, 1997 IP Addressing - Subnets xxx.xxx Subnet Address Host Number

ARKnet Technical Training34 February 20, 1997 Typical Host Numbers

ARKnet Technical Training35 February 20, 1997 Subnet Masks v 32-Bit Value v Used To Determine If An IP Address Is On The Local Subnet v Boolean Logical AND Operation v Defaults Based Upon IP Address Class

ARKnet Technical Training36 February 20, 1997 Boolean Logical AND

ARKnet Technical Training37 February 20, 1997 Subnet Masks Network ID Subnet Number Host Number IP Address Subnet Mask Subnetwork Address

ARKnet Technical Training38 February 20, 1997 Subnet Masks Network ID Subnet Number Host Number IP Address Subnet Mask Subnetwork Address

ARKnet Technical Training39 February 20, 1997 Reserved Addresses v Broadcast Addresses –Host Number = 0 (older) –Host Number = 255 v Loopback Address –IP Address =

ARKnet Technical Training40 February 20, 1997 Address Resolution v Address Resolution Protocol (ARP) –Determines Physical Address Of Another Host On Same Physical Network –Utilizes Broadcasts –ARP Cache u Entries Time Out

ARKnet Technical Training41 February 20, 1997 Address Resolution Protocol A B C D Host A Wants To Send A Packet To Host C Host A Has To Know Host C is

ARKnet Technical Training42 February 20, 1997 Address Resolution Protocol A B C D Host A Transmits Broadcast Frame Containing ARP Request For All Hosts Receive The Frame Request

ARKnet Technical Training43 February 20, 1997 Address Resolution Protocol A B C D Host C Recognizes ARP Request For Its IP And Sends ARP Reply To Host A Other Hosts Ignore ARP Request Reply

ARKnet Technical Training44 February 20, 1997 Address Resolution Protocol A B C D Host A Saves Host C Physical Address In Its ARP Cache For Future Reference Host A Transmits Datagram To Host C Data

ARKnet Technical Training45 February 20, 1997 Bridging and Routing v Bridge –Interconnects Two Physical Nets –Retransmits Frames Received On One Physical Net To The Other –Appearance Is Of One Physical Net –Varying Levels Of Intelligence Of Bridge Program

ARKnet Technical Training46 February 20, 1997 Bridging Bridge

ARKnet Technical Training47 February 20, 1997 Bridging and Routing v Router –Interconnects Multiple Physical Nets –Retransmits Datagrams Received On One Physical Net To Destination Physical Net –Appearance Is Of Multiple Subnets

ARKnet Technical Training48 February 20, 1997 Routing Router

ARKnet Technical Training49 February 20, 1997 Real World Example A B R

ARKnet Technical Training50 February 20, 1997 Real World Example A B R

ARKnet Technical Training51 February 20, 1997 Real World Example v Host A Applies Subnet Mask To Host B IP Address –Determines Host B Is Not On Local Subnet –Has To Use Router To Deliver Packet

ARKnet Technical Training52 February 20, 1997 Real World Example v Host A Sends ARP Request For Router v Router R Responds With ARP Reply to Host A Containing Its Net’s Physical Address v Host A Stores Router R Physical Address In Its ARP Cache v Host A Sends Datagram to Router R

ARKnet Technical Training53 February 20, 1997 Real World Example v Router R Determines Which Physical Net On Which To Transmit Datagram –Match Against Known Subnet Addresses For Physical Nets –Match Against Known Subnet Addresses for Other Routers –Use Default Route If Necessary

ARKnet Technical Training54 February 20, 1997 Real World Example v Router R Determines Destination Is Second Ethernet v Router R Sends ARP Request For Host B v Host B Responds With ARP Reply v Router R Saves Host B Physical Address In Its ARP Cache v Router R Sends Datagram To Host B

ARKnet Technical Training55 February 20, 1997 CIDR v Classless Inter-Domain Routing v Resulted From Huge Internet Growth –Explosion In Numbers Of Nets –Limited IP Address Space –Core Router Limitations v Allocates Blocks of Class C Addresses Rather than Class A or Class B

ARKnet Technical Training56 February 20, 1997 CIDR v CIDR Block Consists Of –Network Address u First Address In CIDR Block –Network Mask u Determines Size Of CIDR Block v CIDR Blocks Are Allocated To Internet Service Providers –ISPs Subdivide Block To Customers

ARKnet Technical Training57 February 20, 1997 CIDR v Common CIDR Block Notation – /21 v Network Addresses – through v Network Mask – v Permits 2048 Contiguous Addresses v Equivalent To 8 Class C Subnets

ARKnet Technical Training58 February 20, 1997 IPng -or- IPv6 v Current IP Address Space –32-Bit –IPv4 v Proposed IP Next Generation Address –128-Bit –IPv6

ARKnet Technical Training59 February 20, 1997 IPng -or- IPv6 v Larger Addresses v Flexible Header Format v Improved Options v Support For Resource Allocation v Provision For Protocol Extension

ARKnet Technical Training60 February 20, 1997 IPng -or- IPv6 v Sample Address – v Colon Hexadecimal Notation –68E6:8C64:FFFF:FFFF:0:1180:96A:FFFF v Zero Compression Allowed –FF05:0:0:0:0:0:0:B3 –FF05::B3

ARKnet Technical Training61 February 20, 1997 Domain Name Services v The Problem With IP Addresses –Hard To Remember –They Change When Network Is Reconfigured or Machine Is Moved v Early Solution Was Host Table v Good Solution Was Domain Name System

ARKnet Technical Training62 February 20, 1997 Host Table v Hard-Coded File –Usually called host.txt –Resides On Each Computer –Updates Must Be Manually Replicated to Each Computer v Sample host.txt – foobar – internic

ARKnet Technical Training63 February 20, 1997 Domain Name System v Names Table Maintained in Central Server (Domain Name Server) v Networked Hosts Configured With DNS Server IP Address v DNS Name Registry v DNS Server Hierarchy v Changes Reflected in One Place

ARKnet Technical Training64 February 20, 1997 Troubleshooting IP Problems v Improperly Configured IP Address –Symptom: No network communication –Symptom: Network unreachable messages –Try: PING router or known host –Check: u IP Address u IP Mask u Gateway (router) address u Domain name server address(es)

ARKnet Technical Training65 February 20, 1997 Troubleshooting IP Problems v Duplicate IP Address –Symptom: Time outs, dropped sessions –Try: Turn off machine and PING its IP address from another machine –Common causes –Maintain GOOD records of IP addresses

ARKnet Technical Training66 February 20, 1997 Troubleshooting IP Problems v Unresolvable domain or host name –Symptom: Unable to resolve domain name –Try: u Similar results on another system? u Other domain names work okay? –Check: u Domain name server addresses u Network connection to domain name server

ARKnet Technical Training67 February 20, 1997 Troubleshooting IP Problems v Unable to connect to Internet site –Symptom: Net unreachable messages –Symptom: Timeouts / No responses –Try: u PING your router u PING noc.arknet.edu u PING ftp.gi.net u PING rs.internic.net –Call ARKnet Network Operations Center

ARKnet Technical Training68 February 20, 1997 ARKnet NOC v Contact NOC to report network outage v Weekdays - 7:00am - 9:00pm –Call Help Desk: v Weekdays - 9:00pm - 7:00am –Call Machine Room: v Weekends & Holidays –Call Machine Room:

ARKnet Technical Training69 February 20, 1997 The End Thank You Very Much For Attending! Are There Any Questions?