• Obtains MAC (physical) address of

• Obtains MAC (physical) address of host or node
• Creates database that maps MAC to host’s IP address (arp cache)
– Used to minimize the number of ARP broadcasts
• ARP table
– Table of recognized MAC-to-IP address mappings
– Saved on computer’s hard disk
– Increases efficiency
– Contains dynamic and static entries
• ICMP (Internet Control Message Protocol)
• Network layer protocol
– Reports on data delivery success/failure
• Announces transmission failures to sender
• ICMP cannot correct errors
– Provides critical network problem troubleshooting information
• ICMPv6 used with IPv6
– Carry out the functions that ICMP, IGMP, and ARP perform in IPv4
• IPv4 Addressing
• Networks recognize two addresses
– Logical address (Network layer)
– Physical address (MAC, hardware)
• IP protocol handles logical addressing
• Specific parameters
– Unique 32-bit number
• Divided into four octets (sets of eight bits) separated by periods
• Example: 144.92.43.178
– Network class determined from first octet
• IPv4 Addressing (cont’d.)
• Class D, Class E rarely used (never assign)
– Class D: value between 224 and 239
• Multicasting
– Class E: value between 240 and 254
• Experimental use
• Eight bits have 256 combinations
– Networks use 1 through 254
– 0: reserved as placeholder
– 255: reserved for broadcast transmission
• IPv4 Addressing (cont’d.)
• Class A devices
– Share same first octet (bits 0-7)
• Network ID
– Host: second through fourth octets (bits 8-31)
• Class B devices
– Share same first two octet (bits 0-15)
– Host: second through fourth octets (bits 16-31)
• Class C devices
– Share same first three octet (bits 0-23)
– Host: second through fourth octets (bits 24-31)
• IPv4 Addressing (cont’d.)
• Loop back address
– First octet equals 127 (127.0.0.1)
– Any IPv4 address starting with 127 is a loopback address
• Loopback test
– Attempting to connect to own machine
– Powerful troubleshooting tool
• Windows XP, Vista, Windows 7
– ipconfig command
• Unix, Linux
– ifconfig command

• Binary and Dotted Decimal Notation
• Dotted decimal notation
– Common way of expressing IP addresses
– Decimal number between 0 and 255 represents each octet
– 256 possibilities -- 28
– Period (dot) separates each decimal
• Dotted decimal address has binary equivalent
– Convert each octet
– Remove decimal points
• Subnet Mask
• 32-bit number identifying a device’s subnet
• Informs the rest of the network about the network to which the device is attached
• Four octets (32 bits) / (4 bytes)
– Expressed in binary or dotted decimal notation
• Assigned same way as IP addresses
– Manually or automatically (via DHCP)
• Subnet Mask (cont’d.)
• IPv6 Addressing
• Composed of 128 bits
• Eight 16-bit fields separated by a colon
• Typically represented in hexadecimal numbers
– Separated by a colon
– Example: FE22:00FF:002D:0000:0000:0000:3012:CCE3
Abbreviations for multiple fields with zero values:
• Eliminate leading zeros:
– Field 00FF can be abbreviated FF
– Field 0000 can be abbreviated 0
– FE22:FF:2D:0:0:0:3012:CCE3
• Substitution of multiple zeros (only perform once):
– Known as double colon
– FE22:FF:2D::3012:CCE3
• IPv6 Addressing (cont’d.)
• Unicast address
– Assigned to a workstation’s network adapter
• Multicast address
– Used for transmitting data to many different devices simultaneously
• Anycast address
– Transmission of a message sent to any one computer of a set of computers
– Assigned to routers and not designed to be assigned to hosts, such as servers or workstations
• Format Prefix: indicates the type of IPv6 address (FE80)
• Modern devices and operating systems can use both IPv4 and IPv6
– Using both on a network is know as a dual-stack approach
• Assigning IP Addresses
• Government-sponsored organizations dole out IP addresses to ISPs
– IANA, ICANN, RIRs
• Most companies and individuals obtain IP addresses from their ISP and not from the government’s higher authorities
• Every network node must have unique IP address
– Error message otherwise
• Assigning IP Addresses (cont’d.)
• Static IP address
– Manually assigned
– To change: modify client workstation TCP/IP properties
– Human error can cause duplication
• Dynamic IP address
– Assigned automatically
– Most common method
• Dynamic Host Configuration Protocol (DHCP)
• DHCP (Dynamic Host Configuration Protocol)
• Automatically assigns device a unique IP address
• Application layer protocol
• Reasons for implementing
– Reduce time and planning for IP address management
– Reduce potential for error in assigning IP addresses
– Enable users to move workstations and printers
– Make IP addressing transparent for mobile users
• DHCP (cont’d.)
• DHCP leasing process
– Device borrows (leases) an IP address while attached to network
• Lease time
– Determined when client obtains IP address at log on
– User may force lease termination
• DHCP service configuration
– Specify leased address range
– Configure lease duration
• Several steps to negotiate client’s first lease


• DHCP (cont’d.)
• Terminating a DHCP Lease
– Expire based on period established in server configuration
– Manually terminated at any time
• Client’s TCP/IP configuration
• Server’s DHCP configuration
• Circumstances requiring lease termination
– DHCP server fails and replaced
• DHCP services run on several server types
– Installation and configurations vary
– Server 2008 R2, Apple Server, Linux Server, etc.
• Private and Link-Local Addresses
• Private addresses
– Allow hosts in organization to communicate across internal network
– Cannot be routed on public network
– See pg. 163
• Specific IPv4 address ranges reserved for private addresses
• IP Version 4 Link-local (IPv4LL) addresses
– Provisional address
– Capable of data transfer only on local network segment
• Private and Link-Local Addresses (cont’d.)
• Zero configuration (Zeroconf)
– Collection of protocols that assign link-local addresses
• 169.254.1.0 – 169.254.254.255
– Part of computer’s operating software
• Automatic private IP addressing (APIPA)
– Service that provides link-local addressing on Windows clients when it cannot contact a DHCP server
• Sockets and Ports
• Processes (services) are assigned unique port numbers
• Process’s socket
– Port number plus host machine’s IP address
• Port numbers
– Simplify TCP/IP communications
– Ensures data is transmitted to the correct application
• Example
– Telnet port number: 23
– IPv4 host address: 10.43.3.87
– Socket address: 10.43.3.87:23
– HTTP://[IPv6_address]:23
• Square brackets are used to enclose the literal IPv6 address
• Sockets and Ports (cont’d.)
• Port number range: 0 to 65535
• Three types
– Well Known Ports
• Range: 0 to 1023
• Operating system or administrator use
– Registered Ports
• Range: 1024 to 49151
• Network users, processes with no special privileges
• Assignments are registered with IANA
– Dynamic and/or Private Ports
• Range: 49152 through 65535
• No use restrictions
• Host Names and DNS (Domain Name System)
• TCP/IP addressing
– Long, complicated numbers
– Not always easy for humans to remember
• People remember words better
• Every device on the Internet is known as a host
• Every host can have a host name
– Name describing device
• A companies mail server might be named
• mail.somecompany.com
• Domain Names
• Domain: group of computers belonging to same organization
• Domain name
– Identifies domain (loc.gov)
– Associated with company, university, government organization
• Fully qualified host name (blogs.loc.gov)
– Local hostname plus domain name

Kết quả (Việt) 1:

• Có được địa chỉ MAC (vật lý) của máy chủ lưu trữ hoặc nút• Tạo ra cơ sở dữ liệu mà ánh xạ MAC tới địa chỉ IP của máy chủ (arp cache)-Được sử dụng để giảm thiểu số lượng các chương trình phát sóng ARP• ARP bàn-Bảng ánh xạ địa chỉ MAC IP được công nhận-Lưu trên đĩa cứng của máy tính-Tăng hiệu quả-Chứa mục năng động và tĩnh• ICMP (giao thức thông điệp điều khiển Internet)• Mạng lớp giao thức-Báo cáo về dữ liệu phân phối thành công/thất bại• Thông báo thất bại truyền cho người gửi• ICMP không thể sửa chữa lỗi-Cung cấp quan trọng các vấn đề mạng thông tin gỡ rối• ICMPv6 sử dụng với IPv6-Thực hiện các chức năng ICMP, IGMP và ARP thực hiện trong IPv4• Địa chỉ IPv4• Mạng nhận ra hai địa chỉ-Hợp lý địa chỉ (Network layer)-Địa chỉ vật lý (MAC, phần cứng)• IP giao thức xử lý địa chỉ hợp lý• Thông số cụ thể-Số 32-bit duy nhất• Chia thành bốn octet (bộ 8 bit) ngăn cách bởi những giai đoạn• Ví dụ: 144.92.43.178-Mạng lớp xác định từ đầu tiên octet• Địa chỉ IPv4 (cont 'd)• Lớp D, hạng E hiếm khi được sử dụng (không bao giờ chỉ định)-Class D: giá trị giữa 224 và 239• Multicasting-Class E: giá trị giữa 240 và 254• Sử dụng thử nghiệm• 8 bit có 256 kết hợp-Mạng sử dụng 1 đến 254-0: dành riêng như là giữ chỗ-255: dành riêng cho phát sóng truyền• Địa chỉ IPv4 (cont 'd)• Loại A thiết bị– Share same first octet (bits 0-7)• Network ID– Host: second through fourth octets (bits 8-31)• Class B devices– Share same first two octet (bits 0-15)– Host: second through fourth octets (bits 16-31)• Class C devices– Share same first three octet (bits 0-23)– Host: second through fourth octets (bits 24-31)• IPv4 Addressing (cont’d.)• Loop back address– First octet equals 127 (127.0.0.1)– Any IPv4 address starting with 127 is a loopback address• Loopback test– Attempting to connect to own machine– Powerful troubleshooting tool• Windows XP, Vista, Windows 7– ipconfig command• Unix, Linux– ifconfig command• Binary and Dotted Decimal Notation• Dotted decimal notation– Common way of expressing IP addresses– Decimal number between 0 and 255 represents each octet– 256 possibilities -- 28 – Period (dot) separates each decimal• Dotted decimal address has binary equivalent– Convert each octet– Remove decimal points• Subnet Mask• 32-bit number identifying a device’s subnet• Informs the rest of the network about the network to which the device is attached• Four octets (32 bits) / (4 bytes)– Expressed in binary or dotted decimal notation• Assigned same way as IP addresses– Manually or automatically (via DHCP)• Subnet Mask (cont’d.)• IPv6 Addressing• Composed of 128 bits• Eight 16-bit fields separated by a colon• Typically represented in hexadecimal numbers– Separated by a colon– Example: FE22:00FF:002D:0000:0000:0000:3012:CCE3Abbreviations for multiple fields with zero values:• Eliminate leading zeros:– Field 00FF can be abbreviated FF– Field 0000 can be abbreviated 0– FE22:FF:2D:0:0:0:3012:CCE3• Substitution of multiple zeros (only perform once):– Known as double colon– FE22:FF:2D::3012:CCE3• IPv6 Addressing (cont’d.)• Unicast address– Assigned to a workstation’s network adapter• Multicast address– Used for transmitting data to many different devices simultaneously• Anycast address– Transmission of a message sent to any one computer of a set of computers – Assigned to routers and not designed to be assigned to hosts, such as servers or workstations• Format Prefix: indicates the type of IPv6 address (FE80)• Modern devices and operating systems can use both IPv4 and IPv6– Using both on a network is know as a dual-stack approach• Assigning IP Addresses• Government-sponsored organizations dole out IP addresses to ISPs– IANA, ICANN, RIRs• Most companies and individuals obtain IP addresses from their ISP and not from the government’s higher authorities• Every network node must have unique IP address– Error message otherwise• Assigning IP Addresses (cont’d.)• Static IP address– Manually assigned– To change: modify client workstation TCP/IP properties– Human error can cause duplication• Dynamic IP address– Assigned automatically– Most common method• Dynamic Host Configuration Protocol (DHCP)• DHCP (Dynamic Host Configuration Protocol)• Automatically assigns device a unique IP address• Application layer protocol• Reasons for implementing – Reduce time and planning for IP address management– Reduce potential for error in assigning IP addresses– Enable users to move workstations and printers– Make IP addressing transparent for mobile users• DHCP (cont’d.)• DHCP leasing process– Device borrows (leases) an IP address while attached to network• Lease time– Determined when client obtains IP address at log on– User may force lease termination• DHCP service configuration– Specify leased address range– Configure lease duration• Several steps to negotiate client’s first lease• DHCP (cont’d.)• Terminating a DHCP Lease– Expire based on period established in server configuration– Manually terminated at any time• Client’s TCP/IP configuration• Server’s DHCP configuration• Circumstances requiring lease termination– DHCP server fails and replaced• DHCP services run on several server types– Installation and configurations vary– Server 2008 R2, Apple Server, Linux Server, etc.• Private and Link-Local Addresses• Private addresses– Allow hosts in organization to communicate across internal network– Cannot be routed on public network– See pg. 163• Specific IPv4 address ranges reserved for private addresses• IP Version 4 Link-local (IPv4LL) addresses– Provisional address– Capable of data transfer only on local network segment• Private and Link-Local Addresses (cont’d.)• Zero configuration (Zeroconf)– Collection of protocols that assign link-local addresses• 169.254.1.0 – 169.254.254.255– Part of computer’s operating software• Automatic private IP addressing (APIPA)– Service that provides link-local addressing on Windows clients when it cannot contact a DHCP server• Sockets and Ports• Processes (services) are assigned unique port numbers• Process’s socket– Port number plus host machine’s IP address• Port numbers– Simplify TCP/IP communications – Ensures data is transmitted to the correct application• Example– Telnet port number: 23– IPv4 host address: 10.43.3.87– Socket address: 10.43.3.87:23– HTTP://[IPv6_address]:23 • Square brackets are used to enclose the literal IPv6 address• Sockets and Ports (cont’d.)• Port number range: 0 to 65535• Three types– Well Known Ports• Range: 0 to 1023• Operating system or administrator use– Registered Ports• Range: 1024 to 49151• Network users, processes with no special privileges• Assignments are registered with IANA– Dynamic and/or Private Ports• Range: 49152 through 65535• No use restrictions
• Host Names and DNS (Domain Name System)
• TCP/IP addressing
– Long, complicated numbers
– Not always easy for humans to remember
• People remember words better
• Every device on the Internet is known as a host
• Every host can have a host name
– Name describing device
• A companies mail server might be named
• mail.somecompany.com
• Domain Names
• Domain: group of computers belonging to same organization
• Domain name
– Identifies domain (loc.gov)
– Associated with company, university, government organization
• Fully qualified host name (blogs.loc.gov)
– Local hostname plus domain name