1 00:00:00,390 --> 00:00:07,440 A Cisco Rodek consists of multiple components the major internal components of esis karate include a 2 00:00:07,440 --> 00:00:14,340 central processing unit or C-p you know various physical interfaces such as serial interfaces or fast 3 00:00:14,370 --> 00:00:23,660 ethernet interfaces or gigabit interfaces a random access memory or RAM ROM or read only memory flash 4 00:00:23,660 --> 00:00:28,820 memory as well as nv ram or non volatile RAM. 5 00:00:28,910 --> 00:00:34,730 A router is similar to a computer and has several hardware and software components. 6 00:00:34,900 --> 00:00:42,380 So as an example in a PC today you may have a flash drive or hard drive and in a similar way a router 7 00:00:42,410 --> 00:00:52,220 has flash as well as memory and C.P the rotas you or central processing unit executes operating instructions 8 00:00:52,850 --> 00:00:58,610 such as system initialization or routing functions and switching functions. 9 00:00:58,610 --> 00:01:06,320 A router may run a rotting protocols such as OSPF and when OSPF recalculates the rats to add to the 10 00:01:06,320 --> 00:01:11,750 running table the central processing unit needs to do those computations. 11 00:01:11,750 --> 00:01:15,600 The Rotto also has RAM or random access memory and spooled. 12 00:01:15,620 --> 00:01:18,270 This is very similar to a PC. 13 00:01:18,330 --> 00:01:27,000 RAM is a volatile memory and any data is stored in RAM is lost when the router is powered down or restarted. 14 00:01:27,340 --> 00:01:29,580 So in the same way as on a PC. 15 00:01:29,610 --> 00:01:38,160 If you are working in Microsoft Word and you lose power to your PC you'll lose any changes to the Microsoft 16 00:01:38,160 --> 00:01:39,610 Word document. 17 00:01:39,690 --> 00:01:44,010 If you haven't saved the document to your hard drive. 18 00:01:44,010 --> 00:01:50,310 So if you turn the PC off and you've made some changes without saving them those changes are lost because 19 00:01:50,310 --> 00:01:55,630 the word changes are only stored in RAM and haven't been written to the hard drive. 20 00:01:55,770 --> 00:02:04,320 So a router has RAM which is read write memory and contains software and data structures that allow 21 00:02:04,320 --> 00:02:06,020 the rodded to function. 22 00:02:06,020 --> 00:02:14,700 Now in some cases with PCs when you boot up a PC the operating system which is stored on the hard drive 23 00:02:14,700 --> 00:02:17,220 is loaded into memory. 24 00:02:17,270 --> 00:02:23,900 That's not always possible because of the size of operating systems and the amount of RAM available 25 00:02:23,900 --> 00:02:25,610 in a PC. 26 00:02:25,610 --> 00:02:35,770 However a Cisco router today copies the entire Cisco Iowas software into RAM Gerring the boot process. 27 00:02:36,170 --> 00:02:42,440 That didn't take place in the past but that's what happens today in a similar way when you make changes 28 00:02:42,440 --> 00:02:46,560 on a Rodda those changes are written to the running configuration. 29 00:02:47,460 --> 00:02:53,670 The running configuration is stored in RAM and unless you save that configuration to the startup config 30 00:02:54,270 --> 00:02:59,830 which is stored in nonvolatile RAM or nv ram your changes will be lost. 31 00:03:00,240 --> 00:03:06,400 So the running configuration of arrays stored in RAM and when you save your configuration it's copy 32 00:03:06,400 --> 00:03:12,510 to the startup config which is stored in nonvolatile RAM which means that when the router is turned 33 00:03:12,510 --> 00:03:17,450 off those configuration changes are saved and not lost. 34 00:03:17,580 --> 00:03:27,090 So nv ram or nonvolatile RAM is used to store information such as the start up config which is not lost 35 00:03:27,480 --> 00:03:34,470 when the router is turned off or loses power so the running configuration file is the file that stores 36 00:03:34,470 --> 00:03:40,520 the configuration commands that the Cisco Iowas software is currently using on the router. 37 00:03:40,840 --> 00:03:45,960 Typically all commands that are configured on the Rodda are stored in the running config. 38 00:03:46,880 --> 00:03:53,900 There are always some exceptions to the rule but generally the show run command shows you the configuration 39 00:03:54,440 --> 00:03:57,200 that's currently being used by the router. 40 00:03:57,230 --> 00:04:02,090 Once again nv ram doesn't lose its information when the radio is powered off. 41 00:04:02,160 --> 00:04:10,390 This is Iowa software uses nv ram to permanently store the router's configuration in the startup config. 42 00:04:10,790 --> 00:04:17,090 When you make changes to the Cisco router using the C'mon lining to face those changes are made to the 43 00:04:17,090 --> 00:04:24,560 running can fake if you want to save for those changes you need to use commands such as copy running 44 00:04:24,560 --> 00:04:33,140 config startup config to copy the configuration from RAM to nv ram or from the running config to the 45 00:04:33,140 --> 00:04:37,470 startup config. 46 00:04:37,480 --> 00:04:44,140 Flash memory is nonvolatile computer memory and is used as the permanent storage for the operating system 47 00:04:44,620 --> 00:04:46,290 and other files. 48 00:04:46,300 --> 00:04:49,020 This is very similar to the hard drive or flash drive. 49 00:04:49,020 --> 00:04:53,030 On PCs today depending on the size of the flash. 50 00:04:53,140 --> 00:04:57,340 Multiple copies of the Cisco Ioway can be stored in Flash. 51 00:04:57,550 --> 00:05:04,240 Other files such as music on hold which is used in coal manage express environments can also be stored 52 00:05:04,240 --> 00:05:05,480 in Flash. 53 00:05:05,560 --> 00:05:14,020 When a Cisco router boots up it will copy the Iowas software from flash into RAM Gerring the boot process 54 00:05:14,470 --> 00:05:17,210 and then the CPA will execute the IRS. 55 00:05:17,380 --> 00:05:25,000 Some very old models of Cisco routers such as the twenty five hundred ran the Ioway from memory and 56 00:05:25,000 --> 00:05:32,440 flash at the same time but these days the entire operating system is copied into RAM and is run from 57 00:05:32,440 --> 00:05:38,530 RAM in a similar way to a hard drive or flash drive on a computer. 58 00:05:38,680 --> 00:05:43,540 When the rotors turned off flash memory doesn't lose its contents. 59 00:05:43,720 --> 00:05:46,970 Rom is another form of permanent storage. 60 00:05:47,110 --> 00:05:52,870 This memory contains microcode for basic functions to start and maintain the router and includes the 61 00:05:52,870 --> 00:05:58,040 bootstrap code and power on self test or post run. 62 00:05:58,070 --> 00:06:05,290 Also contains run monitor or Rumson which is used for password recovery and for Rodda disaster recovery 63 00:06:05,290 --> 00:06:06,570 functions. 64 00:06:06,690 --> 00:06:14,720 Run is nonvolatile So the contents are maintained even when the rod is turned off or rebooted. 65 00:06:14,920 --> 00:06:20,590 The Rotto also stores the IP writing table the stores information about directly connected and remote 66 00:06:20,650 --> 00:06:29,170 networks and is used to determine the best path to a local remote network up cache is also used by the 67 00:06:29,180 --> 00:06:35,830 Rodda and thus contains the IP version for address to mac address mappings which is very similar to 68 00:06:35,830 --> 00:06:37,820 the OP Kashan APC. 69 00:06:38,020 --> 00:06:44,830 The OP cache on broad as is used on ethernet interfaces and is used for example when the Rodda pings 70 00:06:45,000 --> 00:06:47,740 I another device from the local subnet. 71 00:06:47,740 --> 00:06:53,710 The router will send out an upper crust and when it receives an up response that information is stored 72 00:06:53,740 --> 00:06:55,380 in the OP cache. 73 00:06:55,450 --> 00:07:02,890 Typically however it's populated when PCs are forwarding traffic through a router to a remote destination. 74 00:07:02,890 --> 00:07:09,670 PCs will send an op request for their default gateway and the Rotto will reply and hence the OP cache 75 00:07:09,670 --> 00:07:11,210 will be populated. 76 00:07:11,230 --> 00:07:18,040 Routers also have packet buffers when packets are received on interfaces they are stored in buffers 77 00:07:18,700 --> 00:07:21,990 that also stored in buffers before they exit an interface. 78 00:07:22,240 --> 00:07:29,680 As an example if an interface is congested the buffer of the outgoing interface will fill up with packets 79 00:07:30,010 --> 00:07:34,330 in the queue to be processed out of that interface. 80 00:07:34,330 --> 00:07:40,060 I wrote it also has the configuration register which is stored in nv ram. 81 00:07:40,060 --> 00:07:46,960 This is used to control how a router boots you could configure this valley to get a router to boot into 82 00:07:46,990 --> 00:07:54,850 run one or two mode or to bypass the startup config to do it password recovery and can be used for other 83 00:07:54,850 --> 00:07:59,090 functions such as changing the speed of the console port. 84 00:07:59,350 --> 00:08:07,000 Erato has multiple interfaces and may include an exit report which is used in the past for modem connections. 85 00:08:07,180 --> 00:08:08,830 It'll have a console port. 86 00:08:08,830 --> 00:08:16,510 It may have a USP interface it may have serial interfaces for Ethan it interfaces gigabit interfaces 87 00:08:16,780 --> 00:08:23,410 and may contain other components such as PV DMD's which are used in voice environments for transcoding. 88 00:08:23,410 --> 00:08:31,740 These have what are called DSP or digital signal processors to convert analog voice into a digital stream. 89 00:08:31,750 --> 00:08:38,620 Various other types of interfaces and components may be found in routers and even servers can be installed 90 00:08:38,620 --> 00:08:39,550 in routers today.