IPv4 Addressing Flashcards
TCP/IP
Transmission Control Protocol/Internet Protocol
- Suite of protocols and standards that provide functionality of most networks.
- Provides logical addressing and packet forwarding between networks
IP Header
Contains fields that manage logical addressing and forwarding function.
Version Field (IP Header)
- Indicates version of IP in use
Length (IP Header)
Indicates size of header and total packet size, including payload.
- Max theoretical size is 65,535 bytes, but actually much smaller to avoid fragmentation in Ethernet frames
Protocol Field (IP Header)
- Describes what is encapsulated in payload so the host knows how to process it
- IP Protocol type value will indicate TCP (Transmission Control Protocol) or UDP (User Datagram Protocol)
- Some protocols run directly on IP instead of Transport Layer
ICMP/1
Internet Control Message Protocol
- Runs directly on IP rather than on Transport layer
- used for status messaging and connectivity testing
IGMP/2
Internet Group Messaging Protocol
- Runs directly on IP rather than on Transport layer
- used with multicasting
GRE/45
Generic Routing Encapsulation
- Runs directly on IP rather than on Transport layer
- Used to tunnel packets accross an intermediate network.
- Used for some VPNs
EIGRP/88 and OSPF/89
Enhanced Interior Gateway Routing and Open Shortest Path First
- Runs directly on IP rather than on Transport layer
- used by routers to exchange information about paths to remote networks
Network Number (Network ID)
- Number common to all hosts on same IP network
The Host Number (Host ID)
- Identifies a host within an IP network
Network Mask
- Distinguishes network ID and Host ID in IP address
- Conceals host ID portion
- Where there is a 1 in the mask, corresponding digit in IP address is part of network ID
- 1s are always contiguous
- /notation indications number of bits set to 1 in net mask
ARP
Address Resolution Protoclol
- Resolves IP Addresses to hardware addresses
Unicast Packet
- Used by an IPv4 Host to communicate with single recipient
- Addressed to IP address of destination host
Broadcast
- One means of communicating with multiple hosts
- Can be performed by sending packet to network or subnet broadcast address
- All hosts that share the same broadcast address receive the packet
Multicasting
- Allows one host to send contend to other hosts that have identified as interested in receiving hosts content.
- Sent to special destination IP address configured for use with that multicast group
- At layer 2, delivered using special range of MAC addresses
- Intent to receive multicast is signaled by joining multicast group
- IGMP is typically used to configure this
Anycast
- Means that a group of hosts has same IP Address
- When router forwards packet to anycast group it uses a prioritization algorithm to select host that is “closest”
- Allows for load balancing and failover
VLANS
Virtual LANs
- Each interface on managed switch can be assigned a VLAN ID
- Different hosts on same cabling can be appear to be on different LAN segments
- Each VLAN is a separate BD
Other uses for Subnets
- Security and administrative control
- Networks may use different physical or data link technologies
Classful addressing
- Allocates network ID based on first Octet of IP address
- Can be identified using first octet:
Class A: 1-126
Class B: 128-191
Class C: 192-223
Public IP Address
- Can be used to establish connection with other public IP addresses and hosts
- Governed by IANA
- Administered by ISPs
Private IP Addresses
- Non-routable ranges over the internet
- Any org can use private addresses and multiple use them simultaneously
- Can be used through NATing
- Or through a proxy server
- 10.0.0.0 - 10.255.255.255 (Class A Range)
- 172.16.0.0 - 172.31.255.255 (Class B Range)
- 192.168.0.0 - 192.168.255.255 (Clas C range)
APIPA
Automatic Private IP Addressing
- Means for clients that could not reach DCHP to communicate over LAN
- If no response from DCHP, host sets its range to 169.254.1.1 - 169.254.254.254
- Type of addressing is referred to as link local
Class D addresses
- 0.0.0 - 239.255.255.255
- Used for multicasting
Class E addresses
- 240.0.0.0 - 255.255.255.255
- Experimental use and testing
127.0.0.0 - 127.255.255.255
Loopback Addresses
- Special address typically used to check that TCP/IP is installed corrected on local host.
- Does not require physical interface to function.
Subnet Addressing
- Using whole octet boundaries in Network ID can be inflexible
- Has 3 hierarchical levels: network ID, subnet ID and host portion.
- Bits from host portion are allocated as subnet address
- Mask is only used within the IP network
Network Address
- First address in network
- Cannot be assigned to host
Broadcast Address
- Last address in network or subnet
- Cannot be used for hosts
Default Gateway
- When destination IP address appears to be on different network or subnet, host forwards packet to here, instead of delivering locally
