What consist of IPv4 Datagram Header?
Mod 4.1 Internet Protocol Basics
Objective 1.4
IPv4 Datagram Header
- Layer 3 protocol, the Internet Protocol (IP) provides logical network addressing and forwarding
Internet Protocol (IP) header contains fields to manage the logical addressing and forwarding function
- IPv4, the header contains two fields for the 32-bit source and destination addresses
IP protocol type
- Indicate a Transmission Control Protocol (TCP/6) segment or a User Datagram Protocol (UDP/17) datagram
The Internet Protocol provides logical network addressing and forwarding.
What Network layer protocols run directly on IP?
Mod 4.1 Internet Protocol Basics
Objective 1.4
picture
The Internet Protocol (IP) is a fundamental protocol in the network layer of the Internet protocol suite.
Layer 2 vs Layer 3 Addressing and Forwarding?
Mod 4.1 Internet Protocol Basics
Objective 1.4
Layer 2 vs Layer 3 Addressing and Forwarding
Layer 2 - switching
Layer 3 - routing
Nodes within each subnet can address one another directly (they are in the same broadcast domain), but they can only communicate with nodes in other subnets via the router
Layer 2 addressing is used for communication within the same broadcast domain.
What does ARP stand for?
Mod 4.1 Internet Protocol Basics
Objective 1.4
Address Resolution Protocol
- TCP/IP suite includes the Address Resolution Protocol (ARP) to perform the task of resolving an IPv4 address to a hardware MAC address
ARP is part of the TCP/IP suite.
Unicast and Broadcast Addressing
Mod 4.1 Internet Protocol Basics
Objective 1.4
Unicast - IP host wants to send a packet to a single recipient
- Unicast traffic, IP packets must be delivered to hosts using layer 2 MAC addresses
Broadcast - local host needs to communicate with multiple hosts, can be performed by sending a packet to the network or subnet’s broadcast address, is the last address in any IP network or subnet
- Broadcast domain boundaries are established at the Network layer by routers layer 3
- Layer 2, broadcasts are delivered using the group MAC address ( ff:ff:ff:ff:ff:ff)
- legacy devices hubs and bridges every port on all physically connected nodes is part of the same layer 2 broadcast domain, same for basic or unmanaged switch
Unicast traffic requires IP packets to be delivered to hosts using layer 2 MAC addresses.
Multicast and Anycast Addressing
Mod 4.1 Internet Protocol Basics
Objective 1.4
Multicast:
- Sends data to all members of a specific group
- 224.0.0.0 through to 239.255.255.255 is reserved for multicast addressing
- Internet Group Management Protocol (IGMP) is typically used to configure group memberships and IP addresses
Anycast
- Data from the sender is delivered to only the “closest” or best-suited single member of the group
- prioritization algorithm and metrics
Multicast is used for efficient data distribution to multiple recipients.
IPv4 Address Format
Mod 4.2 IP Version 4 Addressing
Objective 1.7
IPv4 Address Format
IP address provides two pieces of information
- network number (Network ID) This number is common to all hosts on the same IP network
- host number (Host ID) This number identifies a host within an IP network
8 bits in each section
EX: 172.17.154.2
128 | 64 | 32 | 16 | 8 | 4 | 2 | 1
binary 0,1
The Network ID is common to all hosts on the same IP network, while the Host ID identifies a specific host within that network.
Binary/Decimal Conversion
Mod 4.2 IP Version 4 Addressing
Objective 1.7
Binary/Decimal Conversion
21=2, 22=4, 23=8, 24=16, 25=32, 26=64, and 27=128
decimal to binary
The binary system uses base 2, where each digit represents a power of 2.
Binary/Decimal Conversion
Mod 4.2 IP Version 4 Addressing
Objective 1.7
Binary/Decimal Conversion
21=2, 22=4, 23=8, 24=16, 25=32, 26=64, and 27=128
binary to decimal
The binary system uses base 2, where each digit represents a power of 2.
Network Masks
Mod 4.2 IP Version 4 Addressing
Objective 1.7
Network Masks
- mask conceals the host ID portion of the IP address and thereby reveals the network ID portion
- mask and the IPv4 address are the same number of bits, binary 1 in the mask, corresponding binary digit in the IPv4 address is part of the network ID
- 1s in the mask are always contiguous
- /24, /16, /8
This is essential for identifying the network segment of an IP address.
Subnet Masks
Mod 4.2 IP Version 4 Addressing
Objective 1.7
Subnet addressing has three hierarchical levels: a network ID, subnet ID, and host ID
Octet Mask - Binary Octet - Decimal Equivalent
1 - 10000000 - 128
2 - 11000000 - 192
3 - 11100000 - 224
4 - 11110000 - 240
5 - 11111000 - 248
6 - 11111100 - 252
7 - 11111110 - 254
8 - 11111111 - 255
These levels help in organizing and managing IP addresses within a network.
Host Address Ranges?
Mod 4.2 IP Version 4 Addressing
Objective 1.7
Host Address Ranges
- IP network 198.51.100.0/24 allows for 254 possible host IDs. The host ID portion is 8 bits long
The host ID portion is 8 bits long.
Default Gateway
Mod 4.2 IP Version 4 Addressing
Objective 1.7
- default gateway is a router configured with a path to remote networks
- When the destination IPv4 address is on a different IP network or subnet, the host forwards the packet to its default gateway
IP Interface Configuration in Linux
Mod 4.2 IP Version 4 Addressing
Objective 1.7
- YAML Ain’t Markup Language (YAML)
- YAML configuration files are rendered by either systemd-networkd or NetworkManager
What is Classful Addressing?
Mod 4.3 IP Version 4 Subnetting
Objective 1.7
Classful Addressing: IP network and subnet IDs that are defined by network masks
- 26 Class A network addresses
- 16,000 Class B networks, each containing up to about 65,000 hosts
- Class C networks support only 254 hosts each, but there are over two million of them
Classful addressing divides IP addresses into classes based on their leading bits.
Cheat Sheet for subnetting
Mod 4.3 IP Version 4 Subnetting
Objective 1.7
CIDR - Classes Interdomain Routing
Ex: 10.1.1.37/29
8, 16, 32, 40 = 37 is in between 32 - 40
(1) 10.1.1.32 number before the 37
(2) 10.1.1.39
(3) 10.1.1.33
(4) 10.1.1.38
(5) take group size keep doubling til past 37 = .40 10.1.1.40
(6) 8 but (6 useable)
(7) /29 - 248 - 255.255.255.248
This improves network performance and security.
Public vs Private Addressing
Mod 4.3 IP Version 4 Subnetting
Objective 1.7
- public IP address is one that can establish a connection with other public IP networks and hosts over the Internet
- Private IP addresses can be drawn from one of the pools of addresses defined in RFC 1918 as non-routable over the Internet
Class A - 10.0.0.0 to 10.255.255.255
Class B - 172.16.0.0 to 172.31.255.255
Class C - 192.168.0.0 to 192.168.255.255
- router translates between the private and public addresses using a process called Network Address Translation (NAT)
Public IP addresses are routable over the Internet.
What are other Reserved Address Ranges?
Mod 4.3 IP Version 4 Subnetting
Objective 1.7
Other Reserved Address Ranges
IP address (D and E) that use the values above 223.255.255.255
- Class D addresses (224.0.0.0 through 239.255.255.255) are used for multicasting
- Class E addresses (240.0.0.0 through 255.255.255.255) are reserved for experimental use and testing
Class A, the range 127.0.0.0 to 127.255.255.255 (or 127.0.0.0/8) is reserved. This range is used to configure a loopback address
Class D addresses are used for multicasting.
What is Classless Inter-Domain Routing?
Mod 4.3 IP Version 4 Subnetting
Objective 1.7
Classless Inter-Domain Routing (CIDR) uses bits normally assigned to the network ID to mask the complexity of the subnet and host addressing scheme within that network. CIDR is also sometimes described as supernetting
What is Variable Length Subnet Masks?
Mod 4.3 IP Version 4 Subnetting
Objective 1.7
Allows a network designer to allocate ranges of IP addresses to subnets that match the predicted need for numbers of subnets and hosts per subnet more closely
What is ipconfig?
Mod 4.4 IP Troubleshooting Tools
Objective 5.5
ipconfig command is widely used for basic configuration reporting and support tasks
Linux
Mod 4.4 IP Troubleshooting Tools
Objective 5.5
ifconfig is part of the legacy net-tools package used on LINUX
What is Address Resolution Protocol?
Mod 4.4 IP Troubleshooting Tools
Objective 5.5
- arp command can be used to perform functions related to the ARP table cache. You would use this to diagnose a suspected problem with local addressing and packet delivery
- Linux, the ip neigh command shows entries in the local ARP cache (replacing the old arp command)
Ping command
Mod 4.4 IP Troubleshooting Tools
Objective 5.5
- Internet Control Message Protocol (ICMP) is used to report errors and send messages about the delivery of a packet
- ping can be used to perform a basic connectivity test that is not dependent on the target host running any higher-level applications or services
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Net + Mod 1 Networking Overview22
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Net + Mod 2 Supporting Cabling & Physical Installations18
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Net + Mod 3 Configuring Interface & Switches23
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Net + Mod 4 Configuring Network Addressing31
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Net + Mod 5 Configuring Routing and Advanced Switching36
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Net + Mod 6 Implementing Network Services20
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Net + Mod 7 Explaining Application Services28
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Net + Mod 8 Supporting Network Management20
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Net + Mod 9 Explaining Network Security Concepts17
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Net + Mod 10 Applying Network Security Features15
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Net + Mod 11 Supporting Network Security Design0
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Net + Mod 12 Configuring Wireless Networks0
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Net + Mod 13 Comparing Remote Access Methods0
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Net + Mod 14 Summarizing Cloud Concepts0
