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There are two forms of IP addresses. the first IPv4, consists of numbers from 0 to 255 in each of four groupings separated by a decimal point. 192.168.1.1 for instance which is used for most routers. So the number of addresses will be 255 x 255 x 255 x 255. This is a 32 bit system and provides enough addresses for the population of Earth (plus or minus) as it was back then, over 4 billion. The second format is IPv6 which is a 128 bit system. It can support 3.4×1038 addresses. More than enough for the foreseeable future. So your answer depends on which IP packet standard you mean.

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How many addresses are in an address book?

many addresses


Differences between IPV4 header and IPV6 header?

Figure 1 IPv4 Header Figure 2 IPv6 Header One feature of IPv6 that immediately comes to our mind is huge address space. This refers to the fact that, among many elements shown in Figure 1 and 2, the Source Address and the Destination Address has each been expanded from 32 bits to 128 bits. If you just think in terms of pure combination of numbers, there used to be 232 possible ways to represent addresses, but now there are 2128 possible ways to represent them. However, if you compare Figures 1 and 2 again, you will realize that although IPv6 uses four times more digits to express the addresses of the source and the destination, length of the header has not increased much from that of IPv4. This is because header format has been simplified in IPv6. You can see that among many elements (called "field") shown in Figure 1, those shown in red do not exist in Figure 2. One of the important changes is that there is no Options field in Figure 2. In IPv4, Options field can be used to add information about various optional services. For example, information related to encryption can be added here. Because of this, the length of the IPv4 header changes according to the situations. Due to this difference in length, routers that control communications according to the information in the IP header can't judge the length of the header just by looking at the beginning of the packet. This makes it difficult to speed up packet processing with hardware assist. On the other hand, IPv6 moves information related to additional services to a section called extension header. The part shown in Figure 2 is called basic header. Therefore, for plain packets, IP header length is fixed to 40 bytes. In terms of making it easier to process packets with hardware, you can say that IPv6 can be accelerated much easier than IPv4. Another field that exists in Figure 1 but is absent from Figure 2 is the Header Checksum field. A Header Checksum is a number used to check for errors in header information, and is calculated using the numbers in the header. However, problem with this approach is that header contains a number called TTL (Time To Live), which changes every time the packet goes through a router. Because of this, Header Checksum must be recalculated every time the packet goes through a router. If we can free up routers from this type of calculations, we could reduce the delay. Actually, TCP layer that resides above IP layer checks errors of various information including sender address and destination address. Since performing same calculations at the IP layer is redundant and unnecessary, Header Checksum is removed from IPv6. Figure 1 contains 8bit field called "Service Type". This field is used to represent the priority of the packet, for example whether it should be delivered express or with normal speed, and allows communication devices to handle the packet accordingly. Service Type field is composed of TOS (Type of Service) field and Precedence field. TOS field specifies the type of service and contains cost, reliability, throughput, delay, or security. Precedence field specifies the level of priority using eight levels from 0 to 7. IPv6 provides the same function with a field called Traffic Class. Flow Label field has a 20 bits length, and is a field newly established for IPv6. By using this field, packet's sender or intermediate devices can specify a series of packets, such as Voice over IP, as a flow, and request particular service for this flow. Even in the world of IPv4, some communication devices are equipped with the ability to recognize traffic flow and assign particular priority to each flow. However, these devices not only need to check the IP layer information such as address of the sender and the destination, but also need to check the port number which is an information that belongs to a higher layer. Flow Label field attempts to put together all these necessary information and provide them at the IP layer. However, specifics on how to use it is still undecided. As we have seen in this article, IPv6 aims to provide intelligent transmission framework that is easy to handle for intermediate devices by keeping the basic header simple and fixed length.


How many bytes is the data frame made by FCS and the header together?

14 bytes for the header and 4 bytes for the FCS (Frame Check Sequence) for a total of 18 bytes.


What is the difference between IP4 and IP6?

IPv6 is based on IPv4, it is an evolution of IPv4. So many things that we find with IPv6 are familiar to us. The main differences are:1.Simplified header format. IPv6 has a fixed length header, which does not include most of the options an IPv4 header can include. Even though the IPv6 header contains two 128 bit addresses (source and destination IP address) the whole header has a fixed length of 40 bytes only. This allows for faster processing.Options are dealt with in extension headers, which are only inserted after the IPv6 header if needed. So for instance if a packet needs to be fragmented, the fragmentation header is inserted after the IPv6 header. The basic set of extension headers is defined in RFC 2460.2.Address extended to 128 bits. This allows for hierarchical structure of the address space and provides enough addresses for almost every 'grain of sand' on the earth. Important for security and new services/devices that will need multiple IP addresses and/or permanent connectivity.3.A lot of the new IPv6 functionality is built into ICMPv6 such as Neighbor Discovery, Autoconfiguration, Multicast Listener Discovery, Path MTU Discovery.4.Enhanced Security and QoS Features.Answer:IPv4 means Internet Protocol version 4, whereas IPv6 means Internet Protocol version 6.IPv4 is 32 bits IP address that we use commonly, it can be 192.168.8.1, 10.3.4.5 or other 32 bits IP addresses. IPv4 can support up to 232 addresses, however the 32 bits IPv4 addresses are finishing to be used in near future, so IPv6 is developed as a replacement.IPv6 is 128 bits, can support up to 2128 addresses to fulfill future needs with better security and network related features. Here are some examples of IPv6 address:1050:0:0:0:5:600:300c:326bff06::c30:0:0:0:0:0:192.1.56.10The most important difference is that it has a larger address space. IPv6 uses 128 bits, instead of the 32 bits used in an IPv4 address.There are also some changes in the header format, and some additional options, like built-in security options. These can be added to IPv4 through additional protocols, so this is really no big deal.IPv4 is like 10.36.05.2 while IPv6 is one huge garble.IPv4 is a 32 bits IP address that we use commonly, it can be 192.168.8.1, 10.3.4.5 or other 32 bits IP addresses. IPv4 can support up to 232 addresses, however the 32 bits IPv4 addresses are finishing to be used in near future, so IPv6 is developed as a replacement.IPv6 is 128 bits, can support up to 2128 addresses to fulfill future needs with better security and network related features.Here are some examples of IPv6 address:1050:0:0:0:5:600:300c:326bff06::c30:0:0:0:0:0:192.1.56.10For More help, you can visit website:http://www.iyogibusiness.comThe main difference, at least the one that is most relevant for a transition from version 4 to version 6, is the length of the addresses. IPv4 uses 4 bytes; IPv6 uses 16 bytes for the address.Mainly, IPv6 has a larger addressing space; IPv6 addresses use 128 bits instead of 32 bits.


What is the definition of system file checker?

A router is an Intermediate System (IS) which operates at the network layer of the OSI reference model. Routers may be used to connect two or more IP networks, or an IP network to an internet connection. A router consists of a computer with at least two network interface cards supporting the IP protocol. The router receives packets from each interface via a network interface and forwards the received packets to an appropriate output network interface. Received packets have all link layer protocol headers removed, and transmitted packets have a new link protocol header added prior to transmission. The router uses the information held in the network layer header (i.e. IP header) to decide whether to forward each received packet, and which network interface to use to send the packet. Most packets are forwareded based on the packet's IP destination address, along with routing information held within the router in a routing table. Before a packet is forwarded, the processor checks the Maximum Transfer Unit (MTU) of the specified interface. Packets larger than the interface's MTU must be fragmented by the router into two or more smaller packets. If a packet is received which has the Don't Fragment (DF) bit set in the packet header, the packet is not fragmented, but instead discarded. In this case, an ICMP error message is returned to the sender (i.e. to the original packet's IP source address) informing it of the interface's MTU size. This forms the basis for Path MTU discovery (PMTU). The routing and filter tables resemble similar tables in link layer bridges and switches. Except, that instead of specifying link hardware addresses (MAC addresses), the router table sepcify network (IP addresses). The routing table lists known IP destination addresses with the appropraite network interface to be used to reach that destiantion. A default entry may be specified to be used for all addresses not explicitly defined in the table. A filter table may also be used to ensure that unwanted packets are discarded. The filter may be used to deny access to particular protocols or to prevent unauthorised access from remote computers by discarding packets to specified destination addresses. A router forwards packets from one IP network to another IP network. Like other systems, it determines the IP network from the logical AND of an IP address with the associated subnetwork address mask. One execption to this rule is when a router receives an IP packet to a network broadcast address. In this case, the router discards the packet. Forwarding broadcast packet can lead to severe storms of packets, and if uncontrolled could lead to network overload. A router introduces delay (latency) as it processes the packets it receives. The total delay observed is the sum of many components including: * Time taken to process the frame by the data link protocol * Time taken to select the correct output link (i.e. filtering and routing) * Queuing delay at the output link (when the link is busy) * Other activities which consume processor resources (computing routing tables, network management, generation of logging information) The router queue of packets waiting to be sent also introduces a potential cause of packet loss. Since the router has a finite amount of buffer memory to hold the queue, a router which receives packets at too high a rate may experience a full queue. In this case, the router ahs no other option than to simply discard excess packets. If required, these may later be retransmitted by a transport protocol. Architecture of a router Routers are often used to connect together networks which use different types of links (for instance an HDLC link connecting a WAN to a local Ethernet LAN). The optimum (and maximum) packet lengths (i.e. the maximum transmission unit (MTU)) is different for different types of network. A router may therefore uses IP to provide segmentation of packets into a suitable size for transmission on a network. Associated protocols perform network error reporting (ICMP), communication between routers (to determine appropriate routes to each destination) and remote monitoring of the router operation (network management). The operation of a simple modern router is described on a separate page. If you want to know how the router actually works click HERE.