1 00:00:15,060 --> 00:00:18,710 So let's optimize the links between the two core switches 2 00:00:18,720 --> 00:00:30,690 using ether channel. Once again show spanning tree VLAN 10 shows us that on core 1 all ports are 3 00:00:30,690 --> 00:00:40,570 forwarding but if we have a look at VLAN 20 notice port 24 is blocking something similar is 4 00:00:40,570 --> 00:00:52,270 shown on core 2, show spanning tree VLAN 1 port 24 is blocking for VLAN 10 port 24 5 00:00:52,280 --> 00:01:03,510 is blocking. The big issue here is if traffic for example from VLAN 10 is sent to the Internet that traffic 6 00:01:03,510 --> 00:01:11,940 is gonna traverse this link gigabit 1 0 23 because port 24 is blocking. If traffic is 7 00:01:11,940 --> 00:01:20,210 sent from VLAN 20 to this server that traffic is gonna go to core 2 and then go across gigabit 8 00:01:20,220 --> 00:01:24,230 1 0 23 to the servers. 9 00:01:24,300 --> 00:01:31,590 In other words, you may have many devices at the access layer sending traffic to servers on the left 10 00:01:31,590 --> 00:01:39,360 hand side or to devices on the right hand side such as the Internet or other servers any traffic that 11 00:01:39,360 --> 00:01:48,870 goes via core 1 to core 2 can only use port 23 and any traffic that goes to core 2 and then 12 00:01:48,960 --> 00:01:58,200 to core 1 to get to the servers can only use port 23, port 24 even though it's plugged in 13 00:01:58,590 --> 00:02:08,430 in this topology is not used at all for sending traffic from core 1 to core 2. So for VLAN 20 core 14 00:02:08,430 --> 00:02:14,900 1 is blocking port 24, for VLAN 1 core 2 is blocking port 24. 15 00:02:14,940 --> 00:02:27,270 Same is true for VLAN 10, for VLAN 100 core 2 is forwarding but for VLAN 100 core 1 is blocking. So port 16 00:02:27,300 --> 00:02:35,190 24 is not used even though it's plugged in. So to resolve that we want to bond these two links together 17 00:02:35,700 --> 00:02:43,310 in an ether channel. Now in this video, I'm gonna show you some of the issues that you could encounter 18 00:02:43,730 --> 00:02:52,000 with ether channels or link aggregation or port channels, you'll see different names used for this technology. 19 00:02:52,660 --> 00:02:58,790 So as an example one of the things you need to remember is that when you add physical interfaces to 20 00:02:58,820 --> 00:03:05,600 a port-channel you need to do the configuration on the port-channel rather than on the physical interfaces. 21 00:03:06,230 --> 00:03:13,350 The configuration that you do on the logical port channel should filter down to the physical interfaces. 22 00:03:13,520 --> 00:03:20,030 In other words, the config that you apply on the logical port-channel should be copied and applied on 23 00:03:20,030 --> 00:03:22,340 the physical interfaces by the switch. 24 00:03:22,340 --> 00:03:25,860 That doesn't always work or doesn't always happen. 25 00:03:25,910 --> 00:03:31,460 So if you have problems with port-channel you need to verify the configuration on the port-channel 26 00:03:31,850 --> 00:03:37,210 and the physical interfaces and then you need to make sure that everything is the same on both sides 27 00:03:37,220 --> 00:03:42,950 on both logical port-channel and the physical interfaces then shut down 28 00:03:42,950 --> 00:03:48,830 the physical interfaces and then no shut them. So I'm gonna show you a bit of troubleshooting in this 29 00:03:48,890 --> 00:03:55,970 video as I configure port-channels and I'm gonna show you some of the issues that you could encounter 30 00:03:56,180 --> 00:04:02,180 if you do configuration on the physical interfaces but not on the logical port-channel. 31 00:04:02,180 --> 00:04:06,440 So if you configure the physical interfaces are not the logical port-channel, 32 00:04:06,440 --> 00:04:13,640 you can have issues where the port channel is for example an access port rather than a trunk port even 33 00:04:13,640 --> 00:04:17,959 though your physical interfaces are configured as trunk ports. 34 00:04:17,959 --> 00:04:25,460 The moral of the story is make sure that the configuration of the port-channel and the physical 35 00:04:25,460 --> 00:04:27,350 interfaces is the same. 36 00:04:27,350 --> 00:04:34,550 Once you've shut down the physical interfaces if needed confirm that the configuration is the same and 37 00:04:34,550 --> 00:04:35,390 then no shut 38 00:04:35,390 --> 00:04:44,070 the physical interfaces. So to set up ether channel we're going to go on to the interfaces and in this case 39 00:04:44,070 --> 00:04:51,540 I'll use a range command and I'll specify both interfaces I'll shut both down. 40 00:04:51,660 --> 00:04:56,650 It's a good idea to shut your interfaces down when making changes like this. 41 00:04:56,880 --> 00:05:04,360 In our example, we gonna use what's called a layer 2 ether channel, so we going to run 802.1q 42 00:05:04,360 --> 00:05:07,600 tagging across the links. 43 00:05:07,660 --> 00:05:14,550 It's gonna act as a traditional layer 2 interface rather than a routed or layer 3 interface. 44 00:05:14,880 --> 00:05:18,680 So switch port mode trunk means that it'll act like a trunk 45 00:05:18,820 --> 00:05:21,310 and now we can use the command channel, 46 00:05:24,580 --> 00:05:27,700 group and select a number. 47 00:05:27,700 --> 00:05:35,170 I'm going to select channel-group one, switches can support multiple ether channels or multiple ether 48 00:05:35,170 --> 00:05:37,200 channel groups. 49 00:05:37,210 --> 00:05:43,690 The reason why is that you could use group one to bond these two links together and if you had multiple 50 00:05:43,690 --> 00:05:50,420 ports from your core switch to your access switch let's say from core one to access one you could bond 51 00:05:50,420 --> 00:05:57,730 both of those links together in ether channel 2. So multiple ether channels can be configured. 52 00:05:57,960 --> 00:06:04,290 In this example I'm simply gonna use ether channel 1, I'm gonna specify the mode 53 00:06:04,320 --> 00:06:07,630 and notice here we have five different modes. 54 00:06:07,920 --> 00:06:14,310 Now before we talk about modes you need to understand that we have two link aggregation protocols, LACP 55 00:06:14,310 --> 00:06:23,610 or link aggregation control protocol and PAGP or port aggregation protocol. LACP is an industry standard 56 00:06:23,610 --> 00:06:35,100 protocol, PAGP is a Cisco proprietary protocol. So you can either use LACP or PAGP or you can disable 57 00:06:35,190 --> 00:06:40,740 the use of a protocol and just enable link aggregation on a port. 58 00:06:40,830 --> 00:06:47,850 So if you set the mode to on the switch is not going to negotiate with the switch on the other side 59 00:06:48,150 --> 00:06:49,710 to set up an ether channel. 60 00:06:49,860 --> 00:06:54,150 It's simply gonna turn it on. If you want to use LACP, 61 00:06:54,330 --> 00:07:03,150 you can either use active or passive LACP. Now active means that the switch will use LACP messages 62 00:07:03,150 --> 00:07:11,490 to negotiate with the other side and actively try and form an ether channel with the switch on the other 63 00:07:11,490 --> 00:07:12,830 side of the link. 64 00:07:12,920 --> 00:07:20,220 So if I said active on switch 1 it's gonna try and get switched 2 to form an ether channel on 65 00:07:20,250 --> 00:07:21,360 these ports. 66 00:07:22,830 --> 00:07:27,380 Passive means that the switch doesn't try and actively form an ether channel. 67 00:07:27,510 --> 00:07:34,980 It waits for ether channel messages and if it receives them then it will form an ether channel with 68 00:07:35,070 --> 00:07:41,650 the device on the other side. So active means it's actively trying to form an ether channel. 69 00:07:41,670 --> 00:07:50,200 Passive means it's just passively waiting until the other side initiates the forming of an ether channel. 70 00:07:50,220 --> 00:07:59,280 So you need to specify which protocol to use LACP or PAGP and then with LACP you have the option to 71 00:07:59,280 --> 00:08:04,230 specify either active or passive PAGP does something similar. 72 00:08:04,230 --> 00:08:15,870 We have either desirable or auto, desirable is like active in LACP the switch is gonna actively or 73 00:08:15,870 --> 00:08:27,810 desirably form an ether channel, auto in PAGP is like passive in LACP it's only gona form an ether 74 00:08:27,810 --> 00:08:32,970 channel if the other side initiates the forming of an ether channel. 75 00:08:33,720 --> 00:08:43,640 So in this example, I'm gonna specify active to use LACP and to actively create a link aggregation. 76 00:08:43,770 --> 00:08:50,550 Notice the switch tells us that a port-channel interface has been created, a port-channel interface 77 00:08:50,580 --> 00:08:52,840 is an ether channel interface. 78 00:08:53,070 --> 00:09:04,140 So if we type do show run what we see now is that this port-channel has been created and if we scroll 79 00:09:04,140 --> 00:09:13,710 down we can see that this interface gigabit 1 0 23 is part of the port-channel or ether channel 80 00:09:14,040 --> 00:09:16,110 and so is gigabit 81 00:09:16,110 --> 00:09:21,350 1 0 24. Now I won't no shut the interface yet 82 00:09:21,600 --> 00:09:24,810 I'll go to switch 2 and do something similar. 83 00:09:27,210 --> 00:09:38,440 On switch 2 these interfaces have gone down because we shut them down on switch 1. I'm gonna do something similar 84 00:09:38,440 --> 00:09:38,690 here. 85 00:09:38,710 --> 00:09:43,620 Interface range gigabit 1 0 23 to 24, 86 00:09:44,320 --> 00:09:46,900 I'll shut them down anyway. 87 00:09:47,110 --> 00:10:00,910 Set the switch port mode to trunk, channel Group 1 notice we have options 1 to 48 mode active. 88 00:10:00,910 --> 00:10:03,730 We need to use the same protocols. 89 00:10:03,730 --> 00:10:07,230 So either LACP or PAGP on both sides. 90 00:10:07,450 --> 00:10:15,520 I could have set this side too passive so that switch 1 initiates the ether channel but in this example 91 00:10:15,520 --> 00:10:22,750 I'm gonna get them both to actively try and form a link aggregation. I'll no shut the interfaces on 92 00:10:22,750 --> 00:10:32,190 this side and I'll no shut them on core 1 both physical interfaces have come up and so has the port 93 00:10:32,210 --> 00:10:41,280 channel. So show ether channel summary in the output here. 94 00:10:43,100 --> 00:10:52,280 From the show ether channel summary command we can see that gigabit 1 0 23 and 1 0 24 are part of the 95 00:10:52,280 --> 00:10:52,660 port 96 00:10:52,670 --> 00:10:58,720 channel, so both ports have been put into the port channel. 97 00:10:58,720 --> 00:10:59,580 We can see that port 98 00:10:59,590 --> 00:11:08,440 channel 1 or ether channel 1 is used, S means that it's a layer 2 channel not a layer 3 ether 99 00:11:08,440 --> 00:11:09,290 channel. 100 00:11:09,310 --> 00:11:17,180 In other words, it's using switching rather than routing U means that the ether channel is in use. 101 00:11:17,410 --> 00:11:18,610 So that's great 102 00:11:19,660 --> 00:11:24,880 both ports are part of the ether channel and the ether channel is in use. 103 00:11:25,450 --> 00:11:29,580 Show ether channel summary on this side we see something very similar. 104 00:11:30,160 --> 00:11:34,750 Show ether channel, port channel. 105 00:11:34,750 --> 00:11:40,340 This gives us a lot of information so this command shows us that we have a group. 106 00:11:40,420 --> 00:11:42,830 Group 1, port 107 00:11:42,830 --> 00:11:44,430 channel number is 1. 108 00:11:44,810 --> 00:11:47,780 The channel has been up for this length of time. 109 00:11:47,960 --> 00:11:50,540 There are two ports in the ether channel. 110 00:11:50,540 --> 00:12:02,330 We are using LACP as the protocol on the channel and these two ports gigabit 1 0 23 and 24 are active 111 00:12:02,660 --> 00:12:04,400 in the channel. 112 00:12:04,400 --> 00:12:13,130 This is the time since the last port was bundled so gigabit 1 0 24 was added to the ether channel about 113 00:12:13,130 --> 00:12:16,490 1 minute and 38 seconds ago. On this side 114 00:12:16,490 --> 00:12:21,440 we should see something very similar. So show ether channel port channel. 115 00:12:21,500 --> 00:12:25,930 Notice we can see that both ports are active in the channel. 116 00:12:26,030 --> 00:12:28,070 That's good and that's what we want to see.