1 00:00:00,910 --> 00:00:05,670 In this example I've got three physical rod is connected as follows. 2 00:00:05,680 --> 00:00:13,680 Rotto one is connected via serial one slash 0 to Rodda two on cereal One solution is zero. 3 00:00:13,680 --> 00:00:16,940 These two rhodos 1841 Cecka Radhe Radhe. 4 00:00:17,070 --> 00:00:21,770 One is connected to a 17:21 using serial zeros. 5 00:00:21,820 --> 00:00:24,050 Zero is zero. 6 00:00:24,270 --> 00:00:28,900 They're using back to back serial cables. 7 00:00:29,030 --> 00:00:34,910 One of the first things you want to do when checking your cabling in a back to back lab environment 8 00:00:34,910 --> 00:00:42,580 like this is using the command show controllers serial and then choosing your interface. 9 00:00:42,620 --> 00:00:47,390 So serial 0 1 0. 10 00:00:47,430 --> 00:00:49,380 Now this come on gives you a lot of output. 11 00:00:49,440 --> 00:00:56,690 You can ignore all of it except the piece that we're interested in over here the shows us that this 12 00:00:56,700 --> 00:00:59,540 interface is a DTV interface. 13 00:00:59,670 --> 00:01:03,400 It's a 35 cable connected to the Rodda. 14 00:01:03,630 --> 00:01:05,550 Clocks are currently detected 15 00:01:08,500 --> 00:01:14,170 on serial 0 slushes 0 0. 16 00:01:14,210 --> 00:01:15,770 So here's the command. 17 00:01:15,770 --> 00:01:21,730 This interface is a DC 35 cable with a clock rate to configure it. 18 00:01:22,040 --> 00:01:26,960 So let's pipe both of those and include 35 19 00:01:29,630 --> 00:01:34,550 is the one interface and there's the other interface. 20 00:01:34,560 --> 00:01:41,070 So notice serial 1 slash is 0 0 is a DTV cable. 21 00:01:41,080 --> 00:01:48,490 So in other words the DTV son or the cable is connected to this interface but a DC cable is connected 22 00:01:48,520 --> 00:01:55,580 to this interface so we'd need to do the clock rate on serial 0 slash is zero on the local router. 23 00:01:55,690 --> 00:02:04,550 But on this interface the clock rate would be configured on the other side so the router to show controllers 24 00:02:05,200 --> 00:02:16,510 serial is 0 1 0 and in the output here you can see that it's a v 35 interface with a clock right now 25 00:02:16,510 --> 00:02:18,840 on the DC side. 26 00:02:19,020 --> 00:02:27,400 So interface serial 0 1 0 0 0 you need to specify the clock rate of the interface. 27 00:02:27,400 --> 00:02:31,470 Now this in the real world would be set by your service provider. 28 00:02:31,810 --> 00:02:39,820 So the telco or PC and provider that you are using which could be AT&T or one of those providers pitch 29 00:02:39,820 --> 00:02:46,950 here because it's a back to back cable we need to set the relevant clock rate and you know some of the 30 00:02:46,950 --> 00:02:53,220 clock rates that we could set some of them seem to face dependent so as an example I'll set the clock 31 00:02:53,220 --> 00:02:56,130 rate to 64 kilobits per second. 32 00:02:56,340 --> 00:02:58,700 This command is in bits per second. 33 00:03:00,190 --> 00:03:01,570 So be careful. 34 00:03:01,720 --> 00:03:05,770 The speed of that command is in bits per second. 35 00:03:05,800 --> 00:03:09,360 Now the router doesn't know the actual speed of an interface. 36 00:03:09,370 --> 00:03:18,970 So if we come on do show run interface serial 0 1 0 we can see the clock rate but show interface serial 37 00:03:19,330 --> 00:03:20,730 1 slash is zero 38 00:03:23,960 --> 00:03:32,310 shows us that this router believes that its physical interface speed is 1.5 four megabits per second. 39 00:03:32,480 --> 00:03:34,430 So in other words T1. 40 00:03:34,430 --> 00:03:41,900 So its important that you set the bandwidth statement correctly for your serial interfaces. 41 00:03:41,930 --> 00:03:48,560 It's not unlike Internet where the interface knows at what speed it's sending traffic and receiving 42 00:03:48,560 --> 00:03:49,500 traffic. 43 00:03:49,640 --> 00:03:54,020 You have to actually configure it so should do show run interface. 44 00:03:54,140 --> 00:03:57,130 Cereal is 0 1 0. 45 00:03:57,230 --> 00:04:00,720 Shows us the clock rate and the bandwidth. 46 00:04:00,950 --> 00:04:04,540 They should obviously match ones in kilobits per second. 47 00:04:04,620 --> 00:04:06,120 Ones in bits per second. 48 00:04:08,310 --> 00:04:12,570 Now the clock rate command is only valid on a DC interface. 49 00:04:12,570 --> 00:04:21,450 So on this site on serial 0 1 0 that interface connected to reality too good a DTV cable. 50 00:04:21,450 --> 00:04:29,850 So if we use the command clock rate 64 thousand noticed we told that the command only applies to DC 51 00:04:29,850 --> 00:04:35,970 interfaces so you can set the clock rate but you have to set the bandwidth of the interface to match 52 00:04:36,030 --> 00:04:38,880 the clock rate that's been configured. 53 00:04:38,880 --> 00:04:44,300 So once again that's typically done by your service provider or DC. 54 00:04:44,460 --> 00:04:54,670 In this example because the DC is on the router so it's configured on that interface. 55 00:04:54,780 --> 00:05:02,490 We need to configure the clock rate on the DC side of the back to about cable but to specify the bandwidth 56 00:05:02,550 --> 00:05:04,190 on both sides. 57 00:05:04,190 --> 00:05:11,090 So bandwidth is configured on the side bandwidth and clock rate are configured on that site on this 58 00:05:11,100 --> 00:05:11,790 interface. 59 00:05:11,790 --> 00:05:21,090 This is the DC and once again we can see that by tapping show controllers serial zero slash there is 60 00:05:21,410 --> 00:05:33,510 zero and what you can see in that output of that command is the DCC the clock rate set here is to make. 61 00:05:33,520 --> 00:05:35,360 So we need to configure that right. 62 00:05:35,440 --> 00:05:41,120 And let's just assume in our example that we're going to set at 256 kilobits per second. 63 00:05:41,280 --> 00:05:49,580 So we need to set back to 56 K and then set the clock rate to fifty six thousand. 64 00:05:49,960 --> 00:06:02,100 So show interface serial 0 0 noticed the bandwidth is 56 kilobits per second make sure that the band 65 00:06:02,100 --> 00:06:08,510 with statement is configured correctly as per the clock rate this command actually sets the physical 66 00:06:08,510 --> 00:06:10,680 speed of the interface. 67 00:06:10,790 --> 00:06:18,200 This command tells routing protocols like a whisper funny-I GOP what the speed of the interface is highly. 68 00:06:18,220 --> 00:06:24,790 Running protocols don't query the clock rate because that may be set by an external DCD device. 69 00:06:24,790 --> 00:06:30,930 So on a one sure SCDP neighbor we can see a neighbor or two on this. 70 00:06:30,980 --> 00:06:41,490 A local interface that is in 1841 and it's using Sariel one slash Zira the 17:21 is connected to a local 71 00:06:41,490 --> 00:06:44,500 Saral interface using Sariel one. 72 00:06:44,640 --> 00:06:52,120 So there should be cereal one and the side is the DTG. 73 00:06:52,180 --> 00:06:59,470 So some things to remember the defaulting cancellation on a serial interface on a Cisco router is HGL 74 00:06:59,470 --> 00:07:01,850 see which we can see over there. 75 00:07:02,230 --> 00:07:10,110 You set the clock rate on the DC side keep alive lives a sent every ten seconds to check that the interfaces 76 00:07:10,150 --> 00:07:19,410 up Chessie to the neighbor who says shows me that I made a mistake in the diagram should be routed to 77 00:07:21,320 --> 00:07:27,620 as shown over there so Ratatouille is connected to the 1841 router. 78 00:07:27,690 --> 00:07:28,870 Here it is. 79 00:07:28,890 --> 00:07:39,790 So show CGP neighbor is connected to a number of devices but thats the one that we interested in it's 80 00:07:39,790 --> 00:07:45,760 several interfaces connected to the serial interface of the 1841 router. 81 00:07:45,790 --> 00:07:48,490 So what I'll do is configure an IP address while we hear 82 00:07:51,170 --> 00:07:56,770 with the relevant mosque and let's do the same on this route and then we will do some tests. 83 00:07:56,780 --> 00:08:07,640 So IP address tend to add 1 to 1 to 1 on the first serial interface and then on serial interface serial 84 00:08:07,640 --> 00:08:16,020 0 1 0 and then on the other end to face 1 9 10 1 to 2 to 1. 85 00:08:16,100 --> 00:08:28,580 So hopefully at this point it should be able to ping the 17:21 which it can and then on the second 1841 86 00:08:28,580 --> 00:08:41,520 Radha get an IP address on and it should be able to ping 10 1 1 1 rather 10 1 on 1 which it can do is 87 00:08:41,530 --> 00:08:43,630 running between those two routers. 88 00:08:43,630 --> 00:08:48,390 The relationship has come up show show IP is P.F. neighbor. 89 00:08:49,090 --> 00:08:51,760 See the full relationship has taken place. 90 00:08:51,760 --> 00:08:53,660 Notice the full relationship. 91 00:08:53,660 --> 00:09:01,030 The shows as a dash because it's a point to point link in this example using HTL see once again show 92 00:09:01,030 --> 00:09:03,970 interface serials 0 0 0 93 00:09:07,330 --> 00:09:15,090 0 0 1 0 notice encapsulation has a deal see on the 17:21 94 00:09:17,570 --> 00:09:24,260 router SPF 1 network and now enable OSPF and all interfaces 95 00:09:27,810 --> 00:09:30,190 can see the relationship here is come up. 96 00:09:30,810 --> 00:09:40,490 So the 17:21 should be able to ping the router show IP who is PEF neighbor. 97 00:09:40,860 --> 00:09:50,090 We can see two full relationships are established and now the 17:21 campaign the second 1841 Rodda.