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| IP, Internet protocol |
| Protocol suite: | TCP/IP. |
| Type: | Network layer protocol, connectionless. |
| Ethertype: | 0x0800. |
| SNMP MIBs: | iso.org.dod.internet.mgmt.mib-2.ip (1.3.6.1.2.1.4) iso.org.dod.internet.mgmt.mib-2.ipMIB (1.3.6.1.2.1.48) |
| Working groups: | diffserv,
Differentiated Services. ip1394, IP Over IEEE 1394. |
| Links: | IP option numbers. IP protocol numbers. Differentiated Services Field Codepoints. |
| MAC header | IP header | Data ::: |
IP header:
| 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Version | IHL | TOS | Total length | ||||||||||||||||||||||||||||
| Identification | Flags | Fragment offset | |||||||||||||||||||||||||||||
| TTL | Protocol | Header checksum | |||||||||||||||||||||||||||||
| Source IP address | |||||||||||||||||||||||||||||||
| Destination IP address | |||||||||||||||||||||||||||||||
| Options and padding ::: | |||||||||||||||||||||||||||||||
Version. 4 bits.
Specifies the format of the IP packet header.
| Version | Description |
|---|---|
| 0 | Reserved. |
| 1 2 3 |
|
| 4 | IP, Internet Protocol. |
| 5 | ST, ST Datagram Mode. |
| 6 | SIP, Simple Internet Protocol. SIPP, Simple Internet Protocol Plus. IPv6, Internet Protocol. |
| 7 | TP/IX, The Next Internet. |
| 8 | PIP, The P Internet Protocol. |
| 9 | TUBA |
| 10 - 14 |
|
| 15 | Reserved. |
IHL, Internet Header
Length. 4 bits.
Specifies the length of the IP packet header in 32 bit words. The minimum value
for a valid header is 5.
TOS, Type of Service.
8 bits.
Specifies the parameters for the type of service requested. The parameters may
be utilized by networks to define the handling of the datagram during transport.
The M bit was added to this field in RFC 1349.
| 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 |
|---|---|---|---|---|---|---|---|
| Precedence | D | T | R | M | 0 | ||
Precedence. 3 bits.
Value Description 0 Routine. 1 Priority. 2 Immediate. 3 Flash. 4 Flash override. 5 CRITIC/ECP. 6 Internetwork control. 7 Network control.
D. 1 bit.
Minimize delay.
Value Description 0 Normal delay. 1 Low delay.
T. 1 bit.
Maximize throughput.
Value Description 0 Normal throughput. 1 High throughput.
R. 1 bit.
Maximize reliability.
Value Description 0 Normal reliability. 1 High reliability.
M. 1 bit.
Minimize monetary cost.
Value Description 0 Normal monetary cost. 1 Minimize monetary cost.
Total length.
16 bits.
Contains the length of the datagram.
Identification.
16 bits.
Used to identify the fragments of one datagram from those of another. The originating
protocol module of an internet datagram sets the identification field to a value
that must be unique for that source-destination pair and protocol for the time
the datagram will be active in the internet system. The originating protocol
module of a complete datagram clears the MF bit to zero and the Fragment
Offset field to zero.
Flags. 3 bits.
| 00 | 01 | 02 |
|---|---|---|
| R | DF | MF |
R, Reserved. 1 bit.
Should be set to 0.DF, Don't fragment. 1 bit.
Controls the fragmentation of the datagram.
Value Description 0 Fragment if necessary. 1 Do not fragment. MF, More fragments. 1 bit.
Indicates if the datagram contains additional fragments.
Value Description 0 This is the last fragment. 1 More fragments follow this fragment.
Fragment Offset.
13 bits.
Used to direct the reassembly of a fragmented datagram.
TTL, Time
to Live. 8 bits.
A timer field used to track the lifetime of the datagram. When the TTL field
is decremented down to zero, the datagram is discarded.
Protocol. 8
bits.
This field specifies the next encapsulated protocol.
| Value | Protocol |
|---|---|
| 0 | IPv6 Hop-by-Hop Option. |
| 1 | ICMP, Internet Control Message Protocol. |
| 2 | IGAP, IGMP
for user Authentication Protocol. IGMP, Internet Group Management Protocol. RGMP, Router-port Group Management Protocol. |
| 3 | GGP, Gateway to Gateway Protocol. |
| 4 | IP in IP encapsulation. |
| 5 | ST, Internet Stream Protocol. |
| 6 | TCP, Transmission Control Protocol. |
| 7 | UCL, CBT. |
| 8 | EGP, Exterior Gateway Protocol. |
| 9 | IGRP. |
| 10 | BBN RCC Monitoring. |
| 11 | NVP, Network Voice Protocol. |
| 12 | PUP. |
| 13 | ARGUS. |
| 14 | EMCON, Emission Control Protocol. |
| 15 | XNET, Cross Net Debugger. |
| 16 | Chaos. |
| 17 | UDP, User Datagram Protocol. |
| 18 | TMux, Transport Multiplexing Protocol. |
| 19 | DCN Measurement Subsystems. |
| 20 | HMP, Host Monitoring Protocol. |
| 21 | Packet Radio Measurement. |
| 22 | XEROX NS IDP. |
| 23 | Trunk-1. |
| 24 | Trunk-2. |
| 25 | Leaf-1. |
| 26 | Leaf-2. |
| 27 | RDP, Reliable Data Protocol. |
| 28 | IRTP, Internet Reliable Transaction Protocol. |
| 29 | ISO Transport Protocol Class 4. |
| 30 | NETBLT, Network Block Transfer. |
| 31 | MFE Network Services Protocol. |
| 32 | MERIT Internodal Protocol. |
| 33 | Sequential Exchange Protocol. |
| 34 | Third Party Connect Protocol. |
| 35 | IDPR, Inter-Domain Policy Routing Protocol. |
| 36 | XTP, Xpress Transfer Protocol. |
| 37 | Datagram Delivery Protocol. |
| 38 | IDPR, Control Message Transport Protocol. |
| 39 | TP++ Transport Protocol. |
| 40 | IL Transport Protocol. |
| 41 | IPv6 over IPv4. |
| 42 | SDRP, Source Demand Routing Protocol. |
| 43 | IPv6 Routing header. |
| 44 | IPv6 Fragment header. |
| 45 | IDRP, Inter-Domain Routing Protocol. |
| 46 | RSVP, Reservation Protocol. |
| 47 | GRE, General Routing Encapsulation. |
| 48 | MHRP, Mobile Host Routing Protocol. |
| 49 | BNA. |
| 50 | ESP, Encapsulating Security Payload. |
| 51 | AH, Authentication Header. |
| 52 | Integrated Net Layer Security TUBA. |
| 53 | IP with Encryption. |
| 54 | NARP, NBMA Address Resolution Protocol. |
| 55 | Minimal Encapsulation Protocol. |
| 56 | TLSP, Transport Layer Security Protocol using Kryptonet key management. |
| 57 | SKIP. |
| 58 | ICMPv6,
Internet Control Message Protocol for IPv6. MLD, Multicast Listener Discovery. |
| 59 | IPv6 No Next Header. |
| 60 | Destination Options for IPv6. |
| 61 | Any host internal protocol. |
| 62 | CFTP. |
| 63 | Any local network. |
| 64 | SATNET and Backroom EXPAK. |
| 65 | Kryptolan. |
| 66 | MIT Remote Virtual Disk Protocol. |
| 67 | Internet Pluribus Packet Core. |
| 68 | Any distributed file system. |
| 69 | SATNET Monitoring. |
| 70 | VISA Protocol. |
| 71 | Internet Packet Core Utility. |
| 72 | Computer Protocol Network Executive. |
| 73 | Computer Protocol Heart Beat. |
| 74 | Wang Span Network. |
| 75 | Packet Video Protocol. |
| 76 | Backroom SATNET Monitoring. |
| 77 | SUN ND PROTOCOL-Temporary. |
| 78 | WIDEBAND Monitoring. |
| 79 | WIDEBAND EXPAK. |
| 80 | ISO-IP. |
| 81 | VMTP, Versatile Message Transaction Protocol. |
| 82 | SECURE-VMTP |
| 83 | VINES. |
| 84 | TTP. |
| 85 | NSFNET-IGP. |
| 86 | Dissimilar Gateway Protocol. |
| 87 | TCF. |
| 88 | EIGRP. |
| 89 | OSPF, Open
Shortest Path First Routing Protocol. MOSPF, Multicast Open Shortest Path First. |
| 90 | Sprite RPC Protocol. |
| 91 | Locus Address Resolution Protocol. |
| 92 | MTP, Multicast Transport Protocol. |
| 93 | AX.25. |
| 94 | IP-within-IP Encapsulation Protocol. |
| 95 | Mobile Internetworking Control Protocol. |
| 96 | Semaphore Communications Sec. Pro. |
| 97 | EtherIP. |
| 98 | Encapsulation Header. |
| 99 | Any private encryption scheme. |
| 100 | GMTP. |
| 101 | IFMP, Ipsilon Flow Management Protocol. |
| 102 | PNNI over IP. |
| 103 | PIM, Protocol Independent Multicast. |
| 104 | ARIS. |
| 105 | SCPS. |
| 106 | QNX. |
| 107 | Active Networks. |
| 108 | IPPCP, IP Payload Compression Protocol. |
| 109 | SNP, Sitara Networks Protocol. |
| 110 | Compaq Peer Protocol. |
| 111 | IPX in IP. |
| 112 | VRRP, Virtual Router Redundancy Protocol. |
| 113 | PGM, Pragmatic General Multicast. |
| 114 | any 0-hop protocol. |
| 115 | L2TP, Level 2 Tunneling Protocol. |
| 116 | DDX, D-II Data Exchange. |
| 117 | IATP, Interactive Agent Transfer Protocol. |
| 118 | ST, Schedule Transfer. |
| 119 | SRP, SpectraLink Radio Protocol. |
| 120 | UTI. |
| 121 | SMP, Simple Message Protocol. |
| 122 | SM. |
| 123 | PTP, Performance Transparency Protocol. |
| 124 | ISIS over IPv4. |
| 125 | FIRE. |
| 126 | CRTP, Combat Radio Transport Protocol. |
| 127 | CRUDP, Combat Radio User Datagram. |
| 128 | SSCOPMCE. |
| 129 | IPLT. |
| 130 | SPS, Secure Packet Shield. |
| 131 | PIPE, Private IP Encapsulation within IP. |
| 132 | SCTP, Stream Control Transmission Protocol. |
| 133 | Fibre Channel. |
| 134 | RSVP-E2E-IGNORE. |
| 135 | Mobility Header. |
| 136 | UDPLite. |
| 137 - 252 |
|
| 253 254 |
Experimentation and testing. |
| 255 | Reserved. |
Header checksum.
16 bits.
A 16 bit one's complement checksum of the IP header and IP options.
Source IP
address. 32 bits.
IP address of the sender.
Destination
IP address. 32 bits.
IP address of the intended receiver.
Options. Variable length.
| 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 |
|---|---|---|---|---|---|---|---|
| C | Class | Option | |||||
C, Copy flag. 1 bit.
Indicates if the option is to be copied into all fragments.
Value Description 0 Do not copy. 1 Copy.
Class. 2 bits.
Value Description 0 Control. 1 Reserved. 2 Debugging and measurement. 3 Reserved. Option. 5 bits.
Option Copy Class Value Length Description References 0 0 0 0 1 End of options list. 1 0 0 1 1 NOP. 2 1 0 130 11
Security. 3 1 0 131 variable
Loose Source Route. 4 0 2 68 variable Time stamp. RFC 781, RFC 791 5 1 0 133 3 to 31 Extended Security. RFC 1108 6 1 0 134 Commercial Security. 7 0 0 7 variable Record Route. RFC 791 8 1 0 136 4 Stream Identifier. RFC 791, RFC 1122 9 1 0 137 variable Strict Source Route. RFC 791 10 0 0 10 Experimental Measurement. 11 0 0 11 4 MTU Probe. RFC 1063 12 0 0 12 4 MTU Reply. RFC 1063 13 1 2 205 Experimental Flow Control. 14 1 0 142 Expermental Access Control. 15 0 0 15 16 1 0 144 IMI Traffic Descriptor. 17 1 0 145 Extended Internet Proto 18 0 2 82 12 Traceroute. RFC 1393 19 1 0 147 10 Address Extension. RFC 1475 20 1 0 148 4 Router Alert. RFC 2113 21 1 0 149 6 .. 38 Selective Directed Broadcast Mode. RFC 1770 22 1 0 150 NSAP Addresses. 23 1 0 151 Dynamic Packet State. 24 1 0 152 Upstream Multicast Packet. 25
-
31
Padding. Variable
length.
Used as a filler to guarantee that the data starts on a 32 bit boundary.
Back-to-back.
(RFC 1242: 3.1). Fixed length frames presented at a rate such that there is
the minimum legal separation for a given medium between frames over a short
to medium period of time, starting from an idle state.
Bridge/router.
(RFC 1242: 3.3). A network device that can selectively function as a router
and/or a bridge based on the protocol of a specific frame.
Constant Load.
(RFC 1242: 3.4). Fixed length frames at a fixed interval time.
Data link frame size.
(RFC 1242: 3.5). The number of octets in the frame from the first octet following
the preamble to the end of the FCS, if present, or to the last octet of the
data if there is no FCS.
Forward Tunnel.
(RFC 2344: 1.1). A tunnel that shuttles packets towards the mobile node. It
starts at the home agent, and ends at the mobile node's care-of address.
Frame Loss Rate.
(RFC 1242: 3.6). Percentage of frames that should have been forwarded by a network
device under steady state (constant) load that were not forwarded due to lack
of resources.
Inter Frame Gap.
(RFC 1242: 3.7). The delay from the end of a data link frame as defined in section
3.5, to the start of the preamble of the next data link frame.
Internet Address.
A 32 bit value that contains the network and host number fields. There are five
classes of internet addresses: The class indicates the size of the network and
host fields. Internet addresses are commonly displayed in dotted decimal notation
format XXX.XXX.XXX.XXX.
| Class | 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | 0 | Network bits | Host bits | |||||||||||||||||||||||||||||
| B | 1 | 0 | Network bits | Host bits | ||||||||||||||||||||||||||||
| C | 1 | 1 | 0 | Network bits | Host bits | |||||||||||||||||||||||||||
| D | 1 | 1 | 1 | 0 | Multicast group | |||||||||||||||||||||||||||
| E | 1 | 1 | 1 | 1 | 0 | Reserved | ||||||||||||||||||||||||||
Internet address block allocation.
| Block | Description |
|---|---|
| 0.0.0.0/8 | Addresses in this block refer to source hosts on "this" network. Address 0.0.0.0/32 may be used as a source address for this host on this network; other addresses within 0.0.0.0/8 may be used to refer to specified hosts on this network. |
| 10.0.0.0/8 | Private use networks. Addresses within this block should not appear on the public Internet. |
| 14.0.0.0/8 | Public Data Networks. |
| 24.0.0.0/8 | Cable television networks provisioning. |
| 39.0.0.0/8 | This block was used in the "Class A Subnet Experiment" that commenced in May 1995. The experiment has been completed and this block has been returned to the pool of addresses reserved for future allocation or assignment. This block therefore no longer has a special use and is subject to allocation to a Regional Internet Registry for assignment in the normal manner. |
| 127.0.0.0/8 | Loopback. A datagram sent by a higher level protocol to an address anywhere within this block should loop back inside the host. This is ordinarily implemented using only 127.0.0.1/32 for loopback, but no addresses within this block should ever appear on any network anywhere. |
| 128.0.0.0/16 | This block, corresponding to the numerically lowest of the former Class B addresses, was initially and is still reserved by the IANA. Given the present classless nature of the IP address space, the basis for the reservation no longer applies and addresses in this block are subject to future allocation to a Regional Internet Registry for assignment in the normal manner. |
| 169.254.0.0/16 | Link Local. It is allocated for communication between hosts on a single link. Hosts obtain these addresses by autoconfiguration, such as when a DHCP server may not be found. |
| 172.16.0.0/12 | Private use networks. Addresses within this block should not appear on the public Internet. |
| 191.255.0.0/16 | This block, corresponding to the numerically highest to the former Class B addresses, was initially and is still reserved by the IANA. Given the present classless nature of the IP address space, the basis for the reservation no longer applies and addresses in this block are subject to future allocation to a Regional Internet Registry for assignment in the normal manner. |
| 192.0.0.0/24 | This block, corresponding to the numerically lowest of the former Class C addresses, was initially and is still reserved by the IANA. Given the present classless nature of the IP address space, the basis for the reservation no longer applies and addresses in this block are subject to future allocation to a Regional Internet Registry for assignment in the normal manner. |
| 192.0.2.0/24 | Test-Net. It is often used in conjunction with domain names example.com or example.net in vendor and protocol documentation. Addresses within this block should not appear on the public Internet. |
| 192.88.99.0/24 | 6to4 relay anycast. |
| 192.168.0.0/16 | Private use networks. Addresses within this block should not appear on the public Internet. |
| 198.18.0.0/15 | Network interconnect device benchmark testing. |
| 223.255.255.0/24 | This block, corresponding to the numerically highest of the former Class C addresses, was initially and is still reserved by the IANA. Given the present classless nature of the IP address space, the basis for the reservation no longer applies and addresses in this block are subject to future allocation to a Regional Internet Registry for assignment in the normal manner. |
| 224.0.0.0/4 | Multicast. Formerly known as the Class D address space, it is allocated for use in IPv4 multicast address assignments. |
| 240.0.0.0/4 | This block, formerly known as the Class E address space, is reserved. The "limited broadcast" destination address 255.255.255.255 should never be forwarded outside the (sub-)net of the source. The remainder of this space is reserved for future use. |
Internet datagram.
The data header and message that are transmitted between internet hosts.
Internet fragment.
A part of the data message with intact header fields.
Latency.
(RFC 1242: 3.8). For store and forward devices: The time interval starting when
the last bit of the input frame reaches the input port and ending when the first
bit of the output frame is seen on the output port. For bit forwarding devices:
The time interval starting when the end of the first bit of the input frame
reaches the input port and ending when the start of the first bit of the output
frame is seen on the output port.
Link Speed Mismatch.
(RFC 1242: 3.9). Speed mismatch between input and output data rates.
Multihomed.
A node with multiple IP addresses.
MTU-mismatch behavior.
(RFC 1242: 3.10). The network MTU (Maximum Transmission Unit) of the output
network is smaller than the MTU of the input network, this results in fragmentation.
Overhead behavior.
(RFC 1242: 3.11). Processing done other than that for normal data frames.
Overloaded behavior.
(RFC 1242: 3.12). When demand exceeds available system resources.
Policy based filtering.
(RFC 1242: 3.13). Filtering is the process of discarding received frames by
administrative decision where normal operation would be to forward them.
Restart behavior.
(RFC 1242: 3.14). Reinitialization of system causing data loss.
Reverse Tunnel.
(RFC 2344: 1.1). A tunnel that starts at the mobile node's care-of address and
terminates at the home agent.
Route.
Routing.
An algorithm for moving frames between connected networks.
Single frame behavior.
(RFC 1242: 3.16). One frame received on the input to a device.
Subnet.
Throughput.
(RFC 1242: 3.17). The maximum rate at which none of the offered frames are dropped
by the device.
| ©2004 Muhammad Tayyeb |