Study Notes-ip

Key minutes

IP Protocol Note IP (Internet Protocol)

IP addresses (IP address)

Subnet mask (subnet mask)

IP routing (IP router)

IP 5 class Range

Class A 1-26

Class B 128-191

Class C 192-223

Class D 224-239 Multicast (multicast)

Class E 240-254 scientific research

Subnet mask ABC Type IP default subnet mask

Class A 255.0.0.0

Class B 255.255.0.0

C Tired 255.255.255.0

IP Address Network Segment

Class A 10.0.0.1-10.255.255.254

Class B 172.16.0.1-172.16.31.254

Class C 192.168.0.1-192.168.255.254

Name address range address number have category description maximum CIDR address block

24-bit block10.0.0.0–10.255.255.255 16,777,216 A class a 10.0.0.0/8

20-bit block172.16.0.0–172.31.255.255 1,048,576 Continuous 16 class b 172.16.0.0/12

16-bit block192.168.0.0–192.168.255.255 65,536 continuous 256 class c 192.168.0.0/16

7 Application layer

Application layer such as HTTP, SMTP, SNMP, FTP, Telnet, SIP, SSH, NFS, RTSP, XMPP, Whois, ENRP

6 Presentation layer

Presentation layer such as XDR, ASN.1, SMB, AFP, NCP

5 Session Layer

Session Layer such as ASAP, SSH, ISO 8327/ccitt x.225, RPC, NetBIOS, ASP, Winsock, BSD sockets

4 Transport Layer

Transport Layer such as TCP, UDP, TLS, RTP, SCTP, SPX, ATP, IL

3 Network layer

Network layer such as IP, ICMP, IGMP, IPX, BGP, OSPF, RIP, IGRP, EIGRP, ARP, RARP, x.

2 Data Link layer

Data Link layer such as Ethernet, Token Ring, HDLC, Frame Relay, ISDN, ATM, IEEE 802.11, FDDI, PPP

1 Physical layer

Physical layer such as line, radio, optical fiber

IPV6 addressing

The IPV6 has a much larger encoding address space than the IPV4. This is because IPV6 uses a 128-bit address, while IPV4 uses 32 bits. Therefore, the new address space supports 2128 (about 3.4x1038) addresses, the specific number is 340,282,366,920,938,463,463,374,607,431,768,211,456, can also be said to be 1632, Because 32-bit addresses can fetch 16 different values per bit.

Network address Translation is currently the most efficient way to slow down IPv4 address depletion, while IPV6 's address eliminates reliance on him and is considered sufficient for predictable future use. On the earth population of 7 billion people, the average can be divided into about 4.86x1028 (486117667*1020) a IPv6 address.

The most significant change in IPv6 from IPv4 to IPv6 is the length of the network address. The IPV6 addresses defined in RFC 2373 and RFC 2374 are 128 bits long, and the IPV6 address is generally expressed in 32 hexadecimal digits.

In many cases, the IPV6 address consists of two logical parts: a 64-bit network prefix and a 64-bit host address, which is usually automatically generated from the physical address, called EUI-64 (or 64-bit extension unique identifier)

IPV6 format

IPv6 binary System is a 128-bit length, a group of 16 bits, each separated by a colon ":", can be divided into 8 groups, each expressed in 4-bit hexadecimal notation. For example: 2001:0db8:85a3:08d3:1319:8a2e:0370:7344 is a valid IPV6 address.

At the same time IPv6 can be omitted under certain conditions:

0 of the leading of each digit can be omitted, and the leading number is omitted after the continuation is still 0, for example the next group IPv6 is equal.

2001:0db8:02de:0000:0000:0000:0000:0e13

2001:db8:2de:0000:0000:0000:0000:e13

2001:db8:2de:000:000:000:000:e13

2001:db8:2de:00:00:00:00:e13

2001:db8:2de:0:0:0:0:e13

You can use a double colon "::" to represent a group of 0 or more consecutive 0, but only once:

If four sets of numbers are zero, they can be omitted. Following these ellipsis rules, these two sets of IPv6 are equal.

2001:db8:2de:0:0:0:0:e13

2001:db8:2de::e13

2001:0db8:0000:0000:0000:0000:1428:57ab

2001:0db8:0000:0000:0000::1428:57ab

2001:0db8:0:0:0:0:1428:57ab

2001:0db8:0::0:1428:57ab

2001:0db8::1428:57ab

2001::25de::cade is illegal because the double colon appears two times. It may be one of the sowing situations, resulting in an inability to infer.

2001:0000:0000:0000:0000:25de:0000:cade

2001:0000:0000:0000:25de:0000:0000:cade

2001:0000:0000:25de:0000:0000:0000:cade

2001:0000:25de:0000:0000:0000:0000:cade

If this address is actually an address of IPv4, the latter 32 bits can be represented by 10 decimal digits, so: ffff:192.168.89.9 phase equals:: ffff:c0a8:5909, but not equal to:: 192.168.89.9 and:: c0a8:5909.

In addition, the:: ffff:1.2.3.4 format is called the IPV4 mapping address. The:: 1.2.3.4 format is called IPv4 consistent address, and is now canceled.

IPV4 addresses can be easily converted to IPV6 format. For example, if an address of IPV4 is 135.75.43.52 (16 binary to 0x874b2b34), it can be converted to 0000:0000:0000:0000:0000:ffff:874b:2b34 or:: ffff:874b : 2b34. You can also use the mixed symbol (ipv4-compatible address), which can be: ffff:135.75.43.52.

Classification of IPV6 addresses

IPV6 address can be divided into three kinds: [8]

Unicast (unicast) address

A unicast address identifies a network interface. The protocol sends the packet sent to the address to its interface. A IPV6 unicast address can have a category that represents the name of a particular address, such as a link-local address and a unique region address (Ula,unique local addresses). Unicast addresses include global unicast addresses that are clustered, link-local addresses, and so on.

Anycast (anycast) address

Anycast is IPv6 's unique method of transmitting data, which is like the synthesis of IPv4 unicast (single point propagation) and broadcast (multipoint broadcasting). The IPV4 supports single-point propagation and multicast, where unicast broadcasts communicate directly between sources and destinations, and multicast exists in a single source and multiple destinations for communication.

And anycast in between, it is like the Multipoint broadcast (broadcast), there will be a set of receive node's Address bar table, but the packet designated as Anycast, will only be sent to the nearest or lowest sending cost (according to the routing table) one of the receiving address, When the receiving address receives the packet and responds, it joins the subsequent transmission. Other nodes of the receive list will know that a node address has responded, and they will no longer join the subsequent transfer jobs.

With the current application as an example, the anycast address can only be assigned to a router, cannot be assigned to a computer, and cannot be used as the address of the sending side.

Multicast (multicast) address

The multicast address is also called the multicast address. Multicast addresses are also assigned to a group of different interfaces, and packets sent to the multicast address are sent to all addresses. A multicast address starts with a byte that is one, that is: their predecessor is FF00::/8. The last four bits of its second byte are used to indicate "category".

There are generally node-local (0x1), link-local (0x2), site-local (0x5), organization-local (0x8), and Global (0xE). The minimum 112 bits in the multicast address will form the multicast group identification code, but since the traditional method is generated from the MAC address, only the lowest 32 bits in the group identification code are used. The defined group identification code has multicast address 0x1 for all nodes and 0x2 for all routers.

The address of another multicast group is "Solicited-node multicast Address", which consists of the predecessor ff02::1:ff00:0/104 and the remaining group identification code (minimum 24 bits). These addresses allow the Neighbor Discovery protocol (Ndp,neighbor Discovery Protocol) to interpret the link-layer address so that it does not interfere with all nodes within the zone network.

Special Address

The IANA maintains the official list of IPv6 address spaces [9]. The allocation of a domain-wide unicast address can be found in each regional Internet registry or GRH DFP pages.

Some of the addresses in IPV6 have special meanings:

No address specified

::/128-addresses where all bits are zero are called unspecified addresses. This address cannot be assigned to a network interface and is used in the software only if the host has not yet known its source IP. The router is not forwarding packets that contain unspecified addresses.

Link-Local Address

:: 1/128-is a unicast wrap-back address. If an application sends packets to this address, the IPV6 stack forwards the packets back to the same virtual interface (the equivalent of 127.0.0.1/8 in IPv4).

fe80::/10-These link-local addresses indicate that these addresses are only legal in a zone connection, which is somewhat similar to 169.254.0.0/16 in IPv4.

Unique Region bit field

fc00::/7-Unique zone addresses (ula,unique local address) can only be sent procession in a group of websites. This is defined in RFC 4193 and is used to replace the site's local status domain. This address contains a pseudo-random number of 40 bits to reduce the risk of collisions when a site merge or packet is misrepresented to the network. These addresses, in addition to being used only for regions, have a domain-wide scope, which violates the definition of the site-local address that is replaced by a unique region bit field.

Multicast address

Ff00::/8-This predecessor indicates the multicast address defined in "IP Version 6 addressing Architecture" (RFC 4291) [10]. Some of these addresses have been used to specify special protocols, such as ff0x::101 for all regions of the NTP server (RFC 2375).

Request node multicast addresses (Solicited-node multicast address)

The ff02::1:ffxx:xxxx-xx:xxxx is the three lowest byte in a corresponding unicast or anycast address.

IPV4 Translation Address

:: ffff:x.x.x.x/96-for IPV4 mapping address. (See the conversion mechanism below).

2001::/32-for Teredo tunnels.

The 2002::/16-is used for 6to4.

ORCHID

2001:10::/28-orchid (Overlay routable cryptographic Hash Identifiers) (RFC 4843). These are IPV6 addresses that are not procession and are used to encrypt hash recognition.

File

2001:db8::/32-This predecessor is used for the file (RFC 3849). These addresses are applied to an example of an IPV6 address, or describe a network schema.

Deprecated or deleted usage

::/96-This predecessor was used for IPV4 compatible addresses and is now deleted.

fec0::/10-This site local predecessor indicates that this address is valid only within the organization. It was discarded in the September 2004 RFC3879, and the new system should not support this type of address.

IPV6 Data Packets

The schema description for the IPV6 packet.

The IPV6 packet consists of two main parts: Head and load.

Baotou is the first 64 bits of the packet and contains the source and destination address, protocol version, Communication category (8-bit, packet priority), stream (20-bit, QoS service quality control), packet length (16-bit), Next header (for stack decode, protocol number similar to IPv4), and hop segment limit (8-bit, Time to live, equivalent to the TTL in IPv4). The rear is the load. The MTU is at least 1280 bytes long and 1500 bytes in a common Ethernet environment. The load can be up to 65535 bytes in standard mode, and the length value is set to 0 if the extension header has the "Jumbo payload" option.

IPv6 had two slightly different versions, the original version defined in RFC 1883 (now obsolete) and the now proposed standard version as described in RFC 2460. The two are mainly in the Communication category this option differs, its number of bits from 4 to 8 bits. The other differences are trivial.

Fragmentation (fragmentation) is handled only in IPV6 hosts. In IPv6, the options are removed from the standard header and specified in the Protocol field, similar to the IPV4 Protocol field feature.

Study Notes-ip