[ Pobierz całość w formacie PDF ]
.llThe minimum value for an octet is 0; it contains all 0s.llThe maximum value for an octet is 255; it contains all 1s.lThe allocation of addresses is managed by a central authority.IP Addresses ClassesClass A: N.H.H.HClass B: N.N.H.HClass C: N.N.N.HClass D: for multicastClass E: for researchN = Network number assigned by NICH = Host number assigned by network administratorWhen IP was first developed, there were no classes of addresses.Now, for ease of administration, the IP addresses are broken up into classes.There are only 126 Class A address spaces, but each one can contain approximately 16 million hosts.There are 65,534 Class B address spaces with 65,534 hosts each.There are ore than 16 million Class C address spaces possible, but they only have 254 hosts each.This scheme allows the administrative authority to assign addresses based on the size of the network.The authority designed this system on the assumption that there would be many more small networks than large networks in the networks in the world.Note Class D and E addresses are also defined.Class D addresses start at 224.0 and are used for multicast purposes.Class E addresses start at 240.0 and are used for experimental purposes.IP address Bit PatternsThe most significant bit pattern determines the class of the address, as well as how many bits make up the network portion of the address.lClass A addresses includellRange of network numbers: 1.0 to 126.0llNumber of hosts addresses: 16,777,214llClass B addresses includellRange of network numbers: 128.1.0 to 191.254.0llNumber of host address: 65,534llClass C addresses includellRange of network numbers: 192.1.0 to 223.255.254.0llNumber of host addresses: 254llClass D addresses includellRange of network numbers: 224.0 to 239.255.255.254lRecognising Classes in IP Addresses (First Octet Rule)The first octet rule states that the class of an address can be determined by the numerical value of the first octet.Once the first octet is applied, the router identifies how many bits it must match to interpret the network portion of the address (based on the standard address class).If there is no further identification of additional bits to use as part of the network address, the router can make a routing decision using this address.Note 127.1 is reserved for loopback address.Host addressEach device or interface must have a non-zero host number.A host address of all ones is reserved for an IP into that network.A value of zero means “this network” or “the wire itself” (for example, 172.16.0).It was also used for IP broadcasts in some early TCP/IP implementations, it usually it is rarely found now.The routing table contains entries for network or wire addresses; it usually does not contain any information about hosts.An IP address and subnet address on an interface achieves three purposes:lIt enables the system to process the receipt and transmission of packets.llIt specifies the device's local addressllIt specifies a range of addresses that share the cable with device.lSubnet AddressingFrom the addressing standpoint, subnets are an extension of the network number.Network administrators decide the size of subnets based on organisation and growth needs.Network devices use subnet masks to identify which part of the address is considered network and which remaining part to leave for host addressing.Subnet MaskAn IP address is 32 bits in size, written as four octets.The subnet mask is 32 bits in size, written as four octets.The layout of the subnet mask field is as follows:lBinary 1 for the network bitsllBinary 1 for the subnet bitsllBinary 0 for the host bitslSubnet masks indicate which of the bits in the host field are used to specify different parts (subnets) of a particular network.Decimal Equivalent of Bits PatternsSubnet bits come from the high-order bits of the host field.To determine a subnet mask for an address, add up the decimal values of each position that has a 1 in it.For example,224 = 128 + 64 + 32.Because the subnet mask is not defined by the octet boundary, but by bits, we need to convert dotted decimal addresses to binary and back into dotted decimal so they can work with these addresses.Subnet Mask without Subnets172.16.2.160 10101100 00010000 00000010 10100000255.255.0 11111111 11111111 00000000 0000000010101100 00010000 00000000 00000000172 16 0 0lSubnets not in use - the defaultlThe router extracts the IP destination address from the packet and retrieves the internal subnet mask.The router performs a logical AND operation to obtain the network number.During the logical AND operation, the host portion of the destination address is removed.Routing decisions are then based on network number only.In this example, with no subnetting, the network number “extracted” is 172.16.Subnet Mask with Subnets172.16.2.160 10101100 00010000 00000010 10100000255.255 [ Pobierz całość w formacie PDF ]
zanotowane.pl doc.pisz.pl pdf.pisz.pl przylepto3.keep.pl
.llThe minimum value for an octet is 0; it contains all 0s.llThe maximum value for an octet is 255; it contains all 1s.lThe allocation of addresses is managed by a central authority.IP Addresses ClassesClass A: N.H.H.HClass B: N.N.H.HClass C: N.N.N.HClass D: for multicastClass E: for researchN = Network number assigned by NICH = Host number assigned by network administratorWhen IP was first developed, there were no classes of addresses.Now, for ease of administration, the IP addresses are broken up into classes.There are only 126 Class A address spaces, but each one can contain approximately 16 million hosts.There are 65,534 Class B address spaces with 65,534 hosts each.There are ore than 16 million Class C address spaces possible, but they only have 254 hosts each.This scheme allows the administrative authority to assign addresses based on the size of the network.The authority designed this system on the assumption that there would be many more small networks than large networks in the networks in the world.Note Class D and E addresses are also defined.Class D addresses start at 224.0 and are used for multicast purposes.Class E addresses start at 240.0 and are used for experimental purposes.IP address Bit PatternsThe most significant bit pattern determines the class of the address, as well as how many bits make up the network portion of the address.lClass A addresses includellRange of network numbers: 1.0 to 126.0llNumber of hosts addresses: 16,777,214llClass B addresses includellRange of network numbers: 128.1.0 to 191.254.0llNumber of host address: 65,534llClass C addresses includellRange of network numbers: 192.1.0 to 223.255.254.0llNumber of host addresses: 254llClass D addresses includellRange of network numbers: 224.0 to 239.255.255.254lRecognising Classes in IP Addresses (First Octet Rule)The first octet rule states that the class of an address can be determined by the numerical value of the first octet.Once the first octet is applied, the router identifies how many bits it must match to interpret the network portion of the address (based on the standard address class).If there is no further identification of additional bits to use as part of the network address, the router can make a routing decision using this address.Note 127.1 is reserved for loopback address.Host addressEach device or interface must have a non-zero host number.A host address of all ones is reserved for an IP into that network.A value of zero means “this network” or “the wire itself” (for example, 172.16.0).It was also used for IP broadcasts in some early TCP/IP implementations, it usually it is rarely found now.The routing table contains entries for network or wire addresses; it usually does not contain any information about hosts.An IP address and subnet address on an interface achieves three purposes:lIt enables the system to process the receipt and transmission of packets.llIt specifies the device's local addressllIt specifies a range of addresses that share the cable with device.lSubnet AddressingFrom the addressing standpoint, subnets are an extension of the network number.Network administrators decide the size of subnets based on organisation and growth needs.Network devices use subnet masks to identify which part of the address is considered network and which remaining part to leave for host addressing.Subnet MaskAn IP address is 32 bits in size, written as four octets.The subnet mask is 32 bits in size, written as four octets.The layout of the subnet mask field is as follows:lBinary 1 for the network bitsllBinary 1 for the subnet bitsllBinary 0 for the host bitslSubnet masks indicate which of the bits in the host field are used to specify different parts (subnets) of a particular network.Decimal Equivalent of Bits PatternsSubnet bits come from the high-order bits of the host field.To determine a subnet mask for an address, add up the decimal values of each position that has a 1 in it.For example,224 = 128 + 64 + 32.Because the subnet mask is not defined by the octet boundary, but by bits, we need to convert dotted decimal addresses to binary and back into dotted decimal so they can work with these addresses.Subnet Mask without Subnets172.16.2.160 10101100 00010000 00000010 10100000255.255.0 11111111 11111111 00000000 0000000010101100 00010000 00000000 00000000172 16 0 0lSubnets not in use - the defaultlThe router extracts the IP destination address from the packet and retrieves the internal subnet mask.The router performs a logical AND operation to obtain the network number.During the logical AND operation, the host portion of the destination address is removed.Routing decisions are then based on network number only.In this example, with no subnetting, the network number “extracted” is 172.16.Subnet Mask with Subnets172.16.2.160 10101100 00010000 00000010 10100000255.255 [ Pobierz całość w formacie PDF ]