Presentation on theme: "Network Layer Protocols: ARP, IPv4, ICMP, IPv6 and ICMPv6"— Presentation transcript:
1 Network Layer Protocols: ARP, IPv4, ICMP, IPv6 and ICMPv6
2 Internet Group Management Protocol Reversed ARP Figure Protocols at network layerInternet Group Management ProtocolMulticastingReversed ARPObsoleteInternet Control Message ProtocolProvides error control and messaging capabilities in unicastingAddress Resolution ProtocolFind MAC addressof next-hop hostInternet Protocol:Provides connectionless, best-effort delivery routing of datagrams,is not concerned with the content of the datagrams;looks for a way to move the datagrams to their destination
8 An ARP request is broadcast; an ARP reply is unicast. Note:An ARP request is broadcast; an ARP reply is unicast.
9 Example 1A host with IP address and physical address B has a packet to send to another host with IP address and physical address A46EF45983AB. The two hosts are on the same Ethernet network. Show the ARP request and reply packets encapsulated in Ethernet frames.SolutionFigure 20.6 shows the ARP request and reply packets. Note that the ARP data field in this case is 28 bytes, and that the individual addresses do not fit in the 4-byte boundary. That is why we do not show the regular 4-byte boundaries for these addresses. Note that we use hexadecimal for every field except the IP addresses.
11 20.2 IP Datagram Fragmentation IP provides an unreliable service (i.e., best effort delivery). This means that the network makes no guarantees about the packets proper arrival and any of the following may occur:data corruptionout-of-order delivery (Given packet A is sent before packet B, packet B can arrive before packet A.)duplicate arrivallost or dropped/discarded packagesIPv4, however, does provide some reliability in terms of integrity of the packet, ensuring the IP packet's header is error-free through the use of a checksum. This has the side-effect of discarding packets with bad headers on the spot, and with no required notification to either end (though an ICMP message may be sent). IPv6, on the other hand, has abandoned the use of IP header checksums for the benefit of rapid forwarding through routing elements in the network.To address any of these reliability issues, an upper layer protocol must handle it. For example, to ensure in-order delivery the upper layer may have to cache data until it can be passed up in order.If the upper layer protocol does not self-police its own packet size by first examining the maximum transmission unit (MTU) size, and sends the IP layer too much data, IP is forced to fragment the original datagram into smaller fragments for transmission. IP does provide re-ordering of any fragments that arrive out of order by using the fragmentation flags and offset. Transmission Control Protocol (TCP) is a good example of a protocol that will adjust its segment size to be smaller than the MTU. User Datagram Protocol (UDP) and Internet Control Message Protocol (ICMP) are examples of protocols that disregard MTU size thereby forcing IP to fragment oversized datagrams.The primary reason for the lack of reliability is to reduce the complexity of routers. While this does give routers carte blanche to do as they please with packets, anything less than best effort yields a poor experience for the end user. So, even though no guarantees are made, the better the effort made by the network, the better the experience for the user. Most protocols are built around the idea that error checking is best done at each end of the communication line,
13 IP Datagram Fields VERS - Version number HLEN - Header length, in 32-bit wordsType of Service - How the datagram should be handledTotal Length - Total length, header + dataIdentification, Flags, Frag. Offset - Provides fragmentation of datagrams to allow differing MTU's in the InternetworkTTL - Time-To-LiveProtocol - The upper-layer (Layer 4) protocol sending and receiving the datagramHeader Checksum - An integrity check on the headerSource IP Address and Destination IP Address - 32-bit IP addressesIP Options - Network testing, debugging, security, and other optionsData - Data
18 20.3 ICMP Types of ICMP Messages IP gives unreliable and connectionless datagram delivery.So it gives best-effort delivery service.Efficient use of network resources.No error control/reporting.No messaging capability.ICMP = Internet Control Message ProtocolTypes of ICMP Messages
20 ICMP always reports error messages to the original source. Note:ICMP always reports error messages to the original source.
21 Figure 20.13 Error-reporting messages Packet discardedrouter/host getsDatagram with 0 TTL,or fragments arrive late.Packet discarded,router/host cannotdeliver datagram.Packet sent towrong router.Packet discarded,router/host iscongested. AddedFlow control to IP.Packet discarded,router/host getsambiguous datagram.
22 There is no flow control or congestion control mechanism in IP. Note:There is no flow control or congestion control mechanism in IP.
23 Figure 20.14 Query messages Identify network communication problems betweensystems (host or routers)Get mask to identifynetwork or subnetworkpart of IP address.Get round-trip time,Synchronize clocks.Get information ofalive and functioningrouters.
24 20.4 IPv6 IPv6 Addresses Categories of Addresses IPv6 Packet Format FragmentationICMPv6Transition
25 (2) Population numbers are based on data from the US Census Bureau . WORLD INTERNET USAGE AND POPULATION STATISTICSWorld RegionsPopulation ( 2008 Est.)Internet Users Dec/31, 2000Internet Usage, Latest Data% Population (Penetration)Usage % of WorldUsage GrowthAfrica955,206,3484,514,40051,065,6305.3 %3.5 %1,031.2 %Asia3,776,181,949114,304,000578,538,25715.3 %39.5 %406.1 %Europe800,401,065105,096,093384,633,76548.1 %26.3 %266.0 %Middle East197,090,4433,284,80041,939,20021.3 %2.9 %1,176.8 %North America337,167,248108,096,800248,241,96973.6 %17.0 %129.6 %Latin America/Caribbean576,091,67318,068,919139,009,20924.1 %9.5 %669.3 %Oceania / Australia33,981,5627,620,48020,204,33159.5 %1.4 %165.1 %WORLD TOTAL6,676,120,288360,985,4921,463,632,36121.9 %100.0 %305.5 %NOTES: (1) Internet Usage and World Population Statistics are for June 30, 2008.(2) Population numbers are based on data from the US Census Bureau .(3) Internet usage information comes from data published by Nielsen//NetRatings,by the International Telecommunications Union, by local NIC, and other reliable sources.Source:
37 Technology converging to 4G คาดการณ์กันว่าทุกเทคโนโลยีจะต้องใช้ IP เป็นโปรโตคอลพื้นฐาน
38 Why so slow?As of December 2005, IPv6 accounts for a tiny percentage of the live addresses in the publicly-accessible Internet, which is still dominated by IPv4.Slow because ofclassless addressingnetwork address translation (NAT),When will we runout of IPv4 addresses?APNIC (2003): the available space would last until 2023,Cisco Systems (2005): available addresses would be exhausted in 4–5 years.
39 When is the change?Although adoption of IPv6 has been slow, as of 2008, all United States government systems must support IPv6.Meanwhile China is planning to get a head start implementing IPv6 with their 5 year plan for the China Next Generation Internet.The country of Japan changed to IPv6.
40 Topics discussed in this section: TRANSITION FROM IPv4 TO IPv6Because of the huge number of systems on the Internet, the transition from IPv4 to IPv6 cannot happen suddenly. It takes a considerable amount of time before every system in the Internet can move from IPv4 to IPv6. The transition must be smooth to prevent any problems between IPv4 and IPv6 systems.Topics discussed in this section:Dual Stack Tunneling
45 ในส่วนของประเทศไทยในปัจจุบันได้มีการก่อตั้งคณะทำงานระดับประเทศขึ้นภายใต้ชื่อ Thailand IPv6 Forumกิจกรรมในปัจจุบันของ Thailand IPv6 Forum ได้แก่ การเข้าร่วมเป็นสมาชิกของ Asia-Pacific IPv6 Task Force และการเชื่อมต่อแบบ Native IPv6
46 Summary Internet Protocol ARP RARP (obsolete) ICMP Provides connectionless, best-effort delivery routing of datagrams, is not concerned with the content of the datagrams;looks for a way to move the datagrams to their destinationARPFind MAC address of next-hop hostRARP (obsolete)ICMPProvides error control and messaging capabilities in unicasting
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