1 00:00:00,500 --> 00:00:08,240 What I'd like to point out once again is that each web site is resolved to a different IP address. 2 00:00:08,240 --> 00:00:16,460 Lastly if I ping CNN.com notice that that also resolves to an IP address but it's different to the previous 3 00:00:16,460 --> 00:00:17,660 examples. 4 00:00:17,660 --> 00:00:24,600 DNS is doing the name resolution so it's resolving a domain name to an IP address and that's how I'm 5 00:00:24,620 --> 00:00:28,890 learning the IP address of CNN dot com or Google dot com. 6 00:00:29,000 --> 00:00:35,120 You can ping many of the well-known Web sites on the internet to find out what the IP addresses are. 7 00:00:35,120 --> 00:00:42,200 You could also use this look up which just does a DNS resolution of a domain name rather than trying 8 00:00:42,200 --> 00:00:44,270 to pin the server. 9 00:00:44,270 --> 00:00:50,490 So in summary the devices on the Internet have been configured with IP version 4 addresses. 10 00:00:50,510 --> 00:00:55,180 I'll explain more about the formatting of IP addresses in the next few minutes. 11 00:00:55,400 --> 00:01:03,140 But for now just take note that every device has an IP address and that includes my own machine or the 12 00:01:03,140 --> 00:01:07,860 command IP config will show me the IP address on my local machine. 13 00:01:07,910 --> 00:01:09,420 When using Windows. 14 00:01:09,470 --> 00:01:14,740 So in this example my IP version 4 address is 10.0 0.6. 15 00:01:14,750 --> 00:01:22,960 You'll also notice here that I have an IP version 6 address of 2001 Colin 20 colon colon. 16 00:01:23,240 --> 00:01:28,910 In this video we are concentrating on IP version for addresses but in another video I'll explain IP 17 00:01:28,910 --> 00:01:35,780 version 6 IP version 6 is becoming more and more important because IP addresses are now exhausted in 18 00:01:35,780 --> 00:01:44,240 certain parts of the world IP version 4 or Internet Protocol version 4 is a layer 3 or network a layer 19 00:01:44,240 --> 00:01:47,240 protocol as per the OS model. 20 00:01:47,400 --> 00:01:48,690 You know different video. 21 00:01:48,690 --> 00:01:50,470 I explained the OS on model. 22 00:01:50,510 --> 00:01:57,560 So if you're not sure about layers Please refer to that video IP version 4 is a connection list protocol. 23 00:01:57,560 --> 00:02:01,420 In other words there are no sessions formed when traffic is transmitted. 24 00:02:01,580 --> 00:02:06,800 The transmitter simply sends data without notification to the receiver. 25 00:02:06,800 --> 00:02:10,500 No status information is sent back from the receiver to the transmitter. 26 00:02:10,550 --> 00:02:15,490 It's totally connection less TZP for transmission control protocol. 27 00:02:15,500 --> 00:02:20,680 On the other hand is connection orientated TZP will set up a session. 28 00:02:20,750 --> 00:02:28,070 So before transmission takes place in TZP the transmitter sends what's called a sun or synchronization 29 00:02:28,070 --> 00:02:30,190 message to the receiver. 30 00:02:30,230 --> 00:02:38,210 There's a sim ack message from the receiver to the transmitter and then a ack or acknowledgement message 31 00:02:38,390 --> 00:02:40,430 from the transmitted to the receiver. 32 00:02:40,430 --> 00:02:48,610 So before any data is transmitted but devices using TZP go through what's called the three way handshake. 33 00:02:48,890 --> 00:02:54,960 Some send ack and ack IP on the other hand doesn't do any of that. 34 00:02:55,010 --> 00:02:58,820 Each packet is treated independently of other packets. 35 00:02:58,820 --> 00:03:04,190 That's why traffic can take different paths to get to a destination. 36 00:03:04,220 --> 00:03:11,000 Rodders will route the traffic via different paths based on options such as load balancing because each 37 00:03:11,000 --> 00:03:12,430 packet is independent. 38 00:03:12,530 --> 00:03:15,190 An IP is a connection list protocol. 39 00:03:15,500 --> 00:03:22,110 Routers can also base routing decisions on different values such as bandwidth or hop count. 40 00:03:22,430 --> 00:03:32,240 But it is possible that packets from one session take divergent or different parts to get to a destination. 41 00:03:32,240 --> 00:03:39,260 So for example Ripp will base its routing decisions on hop count which is not good and hence Repp is 42 00:03:39,260 --> 00:03:41,470 not used that often anymore. 43 00:03:41,750 --> 00:03:48,650 OSPF will base it on bandwidths other running protocols will use their own metrics to determine the 44 00:03:48,650 --> 00:03:49,830 best path. 45 00:03:49,850 --> 00:03:56,630 I'll be discussing routing protocols in more detail later in this course but in brief writing protocols 46 00:03:56,630 --> 00:04:01,330 determine the best path or best route from A to B. 47 00:04:01,340 --> 00:04:08,120 This is based on the whole Rockhill addressing structure in IP version for an IP version 6 where we 48 00:04:08,120 --> 00:04:15,080 have both a network and host portion as part of the address Rawdon's base their routing decisions on 49 00:04:15,080 --> 00:04:22,100 the network portion of the address rather than on the host portion of the address and I'll explain network 50 00:04:22,370 --> 00:04:24,390 and host portions in a moment. 51 00:04:24,620 --> 00:04:28,850 IP also only gives best effort to delivery of packets. 52 00:04:28,850 --> 00:04:34,220 There is no guarantee of packet delivery any packet could be misdirected. 53 00:04:34,370 --> 00:04:41,960 It could be duplicated or it could be lost in transmission when sent to a destination and that should 54 00:04:41,960 --> 00:04:45,410 be expected in IP transmissions. 55 00:04:45,410 --> 00:04:52,190 Once again TZP which is a connection oriented protocol has the ability to read transmit packets that 56 00:04:52,190 --> 00:04:58,730 go missing UDP another layer for protocol doesn't retransmit packets. 57 00:04:58,730 --> 00:05:04,130 If they get dropped simply lost and the applications need to take care of that. 58 00:05:04,340 --> 00:05:07,780 There is also no data recovery features in IP. 59 00:05:07,790 --> 00:05:14,750 If the packet for example gets corrupted the end devices need to handle that and not the routers in 60 00:05:14,750 --> 00:05:16,040 between. 61 00:05:16,040 --> 00:05:24,020 So in summary IP has no boltin sessions no data recovery no retransmissions Hialeah protocols such as 62 00:05:24,020 --> 00:05:31,730 TCAP will need to handle dropped packets corrupted packets misdirected packets and so forth. 63 00:05:31,790 --> 00:05:39,850 IP does not provide those features and relies on Hialeah protocols to implement those features. 64 00:05:39,980 --> 00:05:47,300 So let's look at the format of an IP version for address an IP version for address is 32 bits in size 65 00:05:47,480 --> 00:05:56,750 normally written in dotted decimal notation such as this example 10 dot one dot 1.1 each of value such 66 00:05:56,750 --> 00:05:59,770 as 10 is 8 bits in size. 67 00:05:59,780 --> 00:06:07,780 So in other words we have x x x done X with each X being 8 bits in length. 68 00:06:07,910 --> 00:06:13,390 Also known as an octet the total size of the address is 32 bits. 69 00:06:13,400 --> 00:06:15,390 Please refer to the binary video. 70 00:06:15,530 --> 00:06:22,820 If you're not sure about bits and how to convert this address into binary and back again IP addresses 71 00:06:22,820 --> 00:06:29,520 once again have a rock hill structure to enable routing which consists of two main parts. 72 00:06:29,630 --> 00:06:35,810 We have the network portion of an address and the host portion and we look at that in more detail in 73 00:06:35,810 --> 00:06:37,070 a moment. 74 00:06:37,070 --> 00:06:45,620 IP addresses are used for routing in a very similar way to the way DHL or FedEx ranked parcels based 75 00:06:45,620 --> 00:06:51,390 on a destination address route as will route traffic to a destination address. 76 00:06:51,530 --> 00:06:57,800 When unicast packets are transmitted multi-course packets use a different mechanism and do a routing 77 00:06:57,800 --> 00:06:59,500 based on source address. 78 00:06:59,600 --> 00:07:08,420 So as an analogy DHL or FedEx are sending the possible to a destination based on the destination on 79 00:07:08,420 --> 00:07:16,220 the parcel routers are sending packets to destinations based on the destination address in the packet.