ECM 1413 Internet Layer IPv4 Flashcards
What does the Internet Layer allow for?
Network (internet) Layer allows end-to-end device communication
Network layer potential protocols
Routed(IP)
Routing (OSPF & EIGRP)
Supporting (ICMP & ARP)
IPv4 Packet Header Contents
Version
IHL
Type of Service
Packet Length
Identification
Flag
Fragment Offset
Time to live
Protocol
Header Checksum
Source Address
Destination Address
Options
Padding
What is an IPv4 address
Uniquely identifies a device on an IP Network
32-bit broken into four octets using dotted-decimal format
Prefix Length
number of bits representing network portion
- Ex: 192.168.1.1/24
Subnet mask
1s represent network portion and 0s for host portion
- Ex: 11111111.11111111.11111111.00000000
Types of IPv4 addresses
Network address: all host portion bits are 0s
Broadcast address: all host portion bits are 1s
Host Address: between network & broadcast
Subnetting
Dividing a single address block into multiple logical networks
- Borrowing bits from host portion to network portion
Number of subnets = 2^b (borrowed bits)
VLSM (short for “variable length subnet mask”)
a computer networking technique to divide an IP network into subnets with different subnet masks
Public and Private Addresses
- Public addresses used in networks accessible on the internet
- Private addresses used in internal networks are not routable
NAT (network address translation) on the perimeter device
NAT changes a private IPv4 address to a public address
Internet Control Message Protocol (ICMP)
ICMP is a L3 supporting protocol
Messaging protocol - sends messages and operational information
Used for error reporting and diagnosing network issues
- Testing connectivity (ping)
- Observing the path (tracert)
Device Configurations
- IP address
- Subnet mask
- Default gateway
- DNS server
Subnetting example:
borrowing 3 bits from host portion to network portion..
gives 8 subnets
