WEBVTT 1 00:00.000 --> 00:05.540 If you're working your way through this course, then you just saw us talk about 2 00:05.540 --> 00:06.120 the concept 3 00:06.120 --> 00:10.080 of static ether channels and potentially the flaws with them. 4 00:10.080 --> 00:13.780 Specifically, if I have four connections between these two switches and I just 5 00:13.780 --> 00:14.080 want 6 00:14.080 --> 00:18.220 to statically configure these ports to operate in a port channel, then I have 7 00:18.220 --> 00:18.880 to get onto 8 00:18.880 --> 00:24.120 every one of these interfaces and specify that I want them to run in mode on. 9 00:24.120 --> 00:27.280 We'll see this in the lab here coming up and I have to do that on the other 10 00:27.280 --> 00:28.560 side as well. 11 00:28.560 --> 00:31.000 This is a manual configuration at this point. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 11 00:28.560 --> 00:31.000 This is a manual configuration at this point. 12 00:31.000 --> 00:34.000 There's not going to be any negotiation between the switches. 13 00:34.000 --> 00:38.260 They are simply going to trust my configuration as if I'm telling them to run 14 00:38.260 --> 00:39.160 in trunk mode 15 00:39.160 --> 00:41.200 or something like that. 16 00:41.200 --> 00:45.000 If I make a mistake because I don't have these switches right in front of me or 17 00:45.000 --> 00:45.640 something 18 00:45.640 --> 00:49.680 like that, maybe one of them is far away in a different location. 19 00:49.680 --> 00:50.840 I can see these four. 20 00:50.840 --> 00:55.430 I physically got right, but I accidentally configured maybe these four 21 00:55.430 --> 00:57.440 interfaces or maybe somebody 22 00:57.440 --> 01:01.980 miscable that for me when I asked them to go do it or whatever the situation is WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 22 00:57.440 --> 01:01.980 miscable that for me when I asked them to go do it or whatever the situation is 23 01:01.980 --> 01:02.160 . 24 01:02.160 --> 01:05.850 Either way, we see that assuming this port over here is just in a disabled 25 01:05.850 --> 01:06.720 state, maybe 26 01:06.720 --> 01:08.200 there's no connection there. 27 01:08.200 --> 01:14.120 Either way, I think I put four ports into the bundle on both sides and indeed I 28 01:14.120 --> 01:14.760 did, but 29 01:14.760 --> 01:19.810 we see that while the top switch is configured correctly, the bottom switch 30 01:19.810 --> 01:20.840 only put three 31 01:20.840 --> 01:22.200 of these together. 32 01:22.200 --> 01:27.370 We actually have a mismatched bundle here where the top is truly bundling all 33 01:27.370 --> 01:28.000 four and the 34 01:28.000 --> 01:32.490 bottom is only bundling three, meaning that if I get a broadcast packet in, I'm WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 34 01:28.000 --> 01:32.490 bottom is only bundling three, meaning that if I get a broadcast packet in, I'm 35 01:32.490 --> 01:32.960 going 36 01:32.960 --> 01:36.700 to not only send it out the port channel here, but I'm also going to send it 37 01:36.700 --> 01:37.880 out this link 38 01:37.880 --> 01:39.160 over here. 39 01:39.160 --> 01:44.950 Furthermore, if we have a situation where I get a broadcast on the other side 40 01:44.950 --> 01:45.560 and that 41 01:45.560 --> 01:49.360 broadcast gets load balanced and gets sent out this link, then I'm going to 42 01:49.360 --> 01:49.920 take that 43 01:49.920 --> 01:53.850 and turn it around and send it right back out the same port channel, which 44 01:53.850 --> 01:54.960 could potentially 45 01:54.960 --> 01:56.960 create a loop in this case. 46 01:56.960 --> 02:01.300 If once the broadcast is received, the hash says to go right back out the same WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 46 01:56.960 --> 02:01.300 If once the broadcast is received, the hash says to go right back out the same 47 02:01.300 --> 02:02.360 interface, 48 02:02.360 --> 02:05.560 we can see the problems that are going to be generated here. 49 02:05.560 --> 02:11.760 So this is what happens if we configure it manually and it's not necessarily a 50 02:11.760 --> 02:12.360 bad thing 51 02:12.360 --> 02:17.530 to use static configuration like this, but it does leave a little bit to chance 52 02:17.530 --> 02:17.680 . 53 02:17.680 --> 02:22.200 There's the possibility of misconfigurations and we're going to have to be very 54 02:22.200 --> 02:22.800 careful 55 02:22.800 --> 02:28.680 and very clear with our configs to make sure that we avoid this situation. 56 02:28.680 --> 02:34.050 Now, a solution was developed and once again, as we say, this is as old as time WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 56 02:28.680 --> 02:34.050 Now, a solution was developed and once again, as we say, this is as old as time 57 02:34.050 --> 02:35.280 , Cisco created 58 02:35.280 --> 02:41.220 a negotiation protocol that we said is the port aggregation protocol or PAGP 59 02:41.220 --> 02:42.520 and eventually 60 02:42.520 --> 02:47.320 the industry and specifically, in this case, the IEEE, which is a standards 61 02:47.320 --> 02:49.520 creating organization, 62 02:49.520 --> 02:57.290 they created something that we call the link aggregation control protocol or L 63 02:57.290 --> 02:58.080 ACP. 64 02:58.080 --> 03:01.080 And so this is what the industry likes to use. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 64 02:58.080 --> 03:01.080 And so this is what the industry likes to use. 65 03:01.080 --> 03:06.660 And even though PAGP is supported on iOS XE, we typically are going to find 66 03:06.660 --> 03:07.960 that we still 67 03:07.960 --> 03:10.960 favor, in most cases, using LACP. 68 03:10.960 --> 03:15.240 In fact, Cisco makes some devices that only support LACP and they don't even 69 03:15.240 --> 03:16.240 support their 70 03:16.240 --> 03:18.240 own aging protocol. 71 03:18.240 --> 03:24.560 So this LACP is typically what we're going to see with our configurations. 72 03:24.560 --> 03:30.410 Now once again, we do the exact same configuration where I do properly get the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 72 03:24.560 --> 03:30.410 Now once again, we do the exact same configuration where I do properly get the 73 03:30.410 --> 03:32.000 LACP configuration 74 03:32.000 --> 03:36.080 on all four ports up here and I only put them on the three down here. 75 03:36.080 --> 03:40.170 Well, at this point, we're only going to see negotiations successful on these 76 03:40.170 --> 03:41.120 three links. 77 03:41.120 --> 03:44.490 And on this link here, where the misconfiguration happened on the other side, 78 03:44.490 --> 03:45.200 we're going to 79 03:45.200 --> 03:50.440 see that there is no LACP messaging coming inbound. 80 03:50.440 --> 03:54.920 And because there's no LACP messaging, that means I'm going to disable that 81 03:54.920 --> 03:55.560 port or at 82 03:55.560 --> 03:59.560 least remove it from the bundle and treat it like it's an independent port. 83 03:59.560 --> 04:03.760 This prevents all of my loops that could form because now instead of having WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 83 03:59.560 --> 04:03.760 This prevents all of my loops that could form because now instead of having 84 04:03.760 --> 04:04.440 three on the 85 04:04.440 --> 04:08.730 bottom and four on the top, we have three on the bottom and three on the top, 86 04:08.730 --> 04:08.960 thanks 87 04:08.960 --> 04:11.640 to LACP. 88 04:11.640 --> 04:16.480 Now configuration is kind of interesting when we're looking at how to configure 89 04:16.480 --> 04:17.000 LACP and 90 04:17.000 --> 04:19.520 we'll go and take a look at PAGP as well. 91 04:19.520 --> 04:22.800 We mentioned already this concept of mode on. 92 04:22.800 --> 04:30.640 So if I want to configure from a static perspective, I would use mode on. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 92 04:22.800 --> 04:30.640 So if I want to configure from a static perspective, I would use mode on. 93 04:30.640 --> 04:34.360 And what we'll find is as we look at these other two protocols that this mode 94 04:34.360 --> 04:34.760 syntax 95 04:34.760 --> 04:38.760 is still going to be there, I'm just going to change what mode it's running in. 96 04:38.760 --> 04:42.600 And so LACP gives us two modes of operations. 97 04:42.600 --> 04:48.840 We can run in mode active and we can run in mode passive. 98 04:48.840 --> 04:53.720 PAGP has something similar. 99 04:53.720 --> 04:57.180 And in fact, this will sound familiar if you're working away through this 100 04:57.180 --> 04:58.160 course sequentially 101 04:58.160 --> 05:02.160 because once again, we just talked about trunking and DTP. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 101 04:58.160 --> 05:02.160 because once again, we just talked about trunking and DTP. 102 05:02.160 --> 05:07.840 And since DTP was created by Cisco, they use the same terms for PAGP. 103 05:07.840 --> 05:14.900 Specifically, instead of mode active and passive, they use that desirable 104 05:14.900 --> 05:15.240 phrase and 105 05:15.240 --> 05:17.600 then also auto. 106 05:17.600 --> 05:19.280 Auto. 107 05:19.280 --> 05:21.400 So desirable and auto. 108 05:21.400 --> 05:26.320 Now just like with our trunking configuration, if I have active on one side and 109 05:26.320 --> 05:27.120 passive on 110 05:27.120 --> 05:33.440 the other, then we'll be fine because this means I'm going to initialize a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 110 05:27.120 --> 05:33.440 the other, then we'll be fine because this means I'm going to initialize a 111 05:33.440 --> 05:35.000 connection. 112 05:35.000 --> 05:37.760 Passive means I'm going to allow it. 113 05:37.760 --> 05:39.400 Same thing down here with desirable. 114 05:39.400 --> 05:40.840 Desirable is init. 115 05:40.840 --> 05:43.360 Auto is allow. 116 05:43.360 --> 05:47.740 So what we're going to do here is say that if I have an active on passive on 117 05:47.740 --> 05:48.520 two opposite 118 05:48.520 --> 05:53.680 sides, because I initiate and because I allow, this creates a connection. 119 05:53.680 --> 05:57.040 Passive active will create a connection as well. 120 05:57.040 --> 06:01.410 And lastly, if I have passive on one side and passive on the other, this is WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 120 05:57.040 --> 06:01.410 And lastly, if I have passive on one side and passive on the other, this is 121 06:01.410 --> 06:02.040 going to 122 06:02.040 --> 06:05.860 place both of them in a state where they'll allow one, but they won't initiate 123 06:05.860 --> 06:06.920 the connection. 124 06:06.920 --> 06:09.040 So we don't create a connection here. 125 06:09.040 --> 06:12.040 So check on the left, check in the middle. 126 06:12.040 --> 06:13.480 No check on the right. 127 06:13.480 --> 06:17.920 If we have passive on both sides, we will not add a link into a bundle. 128 06:17.920 --> 06:19.760 Desirable and auto is going to be the same way. 129 06:19.760 --> 06:24.190 And again, this reflects the trunk configuration desirable and auto will create 130 06:24.190 --> 06:25.480 a connection. 131 06:25.480 --> 06:27.680 Desirable and desirable will create a connection. 132 06:27.680 --> 06:31.680 Meanwhile, if I have auto and auto, they will not form a connection because WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 132 06:27.680 --> 06:31.680 Meanwhile, if I have auto and auto, they will not form a connection because 133 06:31.680 --> 06:32.360 they're both 134 06:32.360 --> 06:36.280 waiting for the other side to initiate. 135 06:36.280 --> 06:41.320 Now when we look at LACP and PAGP allows this to or enables this as well, but 136 06:41.320 --> 06:42.000 we're going 137 06:42.000 --> 06:45.080 to focus in on LACP moving forward. 138 06:45.080 --> 06:51.180 LACP is going to allow us not just to have some amount of misconfiguration 139 06:51.180 --> 06:52.360 protection, 140 06:52.360 --> 06:56.090 which is huge because once again, we've seen that we can create loops with mis 141 06:56.090 --> 06:56.840 configured 142 06:56.840 --> 07:03.320 ether channels, but also it's going to allow for self healing. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 142 06:56.840 --> 07:03.320 ether channels, but also it's going to allow for self healing. 143 07:03.320 --> 07:08.110 If a link were to go down, we can replace that link if we have another one on 144 07:08.110 --> 07:08.760 standby 145 07:08.760 --> 07:10.840 or in a backup status. 146 07:10.840 --> 07:18.270 So LACP actually allows an iOSXE to support up to 16 links total, but only 147 07:18.270 --> 07:19.600 eight of them 148 07:19.600 --> 07:21.800 can be active. 149 07:21.800 --> 07:25.460 So we were talking about how we can only have eight in a port channel and yeah, 150 07:25.460 --> 07:25.760 we can 151 07:25.760 --> 07:29.470 have eight actively in a bundle, but we can technically configure eight more to 152 07:29.470 --> 07:29.760 be on 153 07:29.760 --> 07:32.320 standby, which is probably excessive. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 153 07:29.760 --> 07:32.320 standby, which is probably excessive. 154 07:32.320 --> 07:36.840 So this would be what we call an N plus N level of redundancy. 155 07:36.840 --> 07:40.000 If I have eight active links, I have eight on standby. 156 07:40.000 --> 07:45.020 Then we might go with something like N plus one or N plus two, where I have one 157 07:45.020 --> 07:45.520 extra link 158 07:45.520 --> 07:48.720 on backup or potentially two extra links on backup. 159 07:48.720 --> 07:52.930 This would be a great way to protect a mission critical type of connection 160 07:52.930 --> 07:54.440 between two switches, 161 07:54.440 --> 07:55.760 maybe two core switches. 162 07:55.760 --> 07:59.980 I create all of my active connections and then I create as many backup links as 163 07:59.980 --> 08:01.240 I desire, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 163 07:59.980 --> 08:01.240 I desire, 164 08:01.240 --> 08:07.720 but this will require using LACP because as a negotiation protocol, that's what 165 08:07.720 --> 08:08.200 's going 166 08:08.200 --> 08:14.450 to be required in order to manage the dynamic addition and removal of links in 167 08:14.450 --> 08:15.600 the bundle. 168 08:15.600 --> 08:20.640 And so using static or mode on here, that's not going to allow for us to 169 08:20.640 --> 08:22.080 dynamically adapt 170 08:22.080 --> 08:25.920 to whatever situation might be occurring. 171 08:25.920 --> 08:29.630 So in this case, what we've got now is we've got a couple of switches, one, two 172 08:29.630 --> 08:30.480 , three, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 172 08:29.630 --> 08:30.480 , three, 173 08:30.480 --> 08:33.720 four, five, six, seven, eight, eight different connections. 174 08:33.720 --> 08:40.160 And then I add a couple of additional backup connections over here. 175 08:40.160 --> 08:42.800 Now when LACP comes up, there's going to be an election. 176 08:42.800 --> 08:46.280 One of these nodes is going to be the master LACP node. 177 08:46.280 --> 08:51.380 This is going to be based on a configured system ID, which consists just like a 178 08:51.380 --> 08:52.080 spanning 179 08:52.080 --> 08:59.180 tree actually, consists of a priority plus the MAC address and the lower number 180 08:59.180 --> 08:59.520 wins. 181 08:59.520 --> 09:05.880 The default priority on a Cisco device is going to be that 3278 number. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 181 08:59.520 --> 09:05.880 The default priority on a Cisco device is going to be that 3278 number. 182 09:05.880 --> 09:08.400 And so you can call it 32K if we want. 183 09:08.400 --> 09:11.320 And this is default on all iOSX devices. 184 09:11.320 --> 09:14.420 So if I wanted one of these to be in charge, then I could pick that, but this 185 09:14.420 --> 09:15.120 really doesn't 186 09:15.120 --> 09:18.760 have a data plane impact. 187 09:18.760 --> 09:22.110 Unlike spanning tree where it absolutely has a data plane impact, depending on 188 09:22.110 --> 09:22.600 which one 189 09:22.600 --> 09:24.720 of our switches is the root switch. 190 09:24.720 --> 09:29.560 So in our case, we usually just allow the election process to occur. 191 09:29.560 --> 09:34.000 And then we're going to allow that device to decide which of these eight to WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 191 09:29.560 --> 09:34.000 And then we're going to allow that device to decide which of these eight to 192 09:34.000 --> 09:34.760 bundle and 193 09:34.760 --> 09:37.280 then which of these to be left out. 194 09:37.280 --> 09:42.400 Then if one of these links goes down, we can, or not we, LACP can then loop in 195 09:42.400 --> 09:42.960 one of those 196 09:42.960 --> 09:47.560 backup links to maintain eight connections, despite the failure. 197 09:47.560 --> 09:51.960 Now if we want to control which of these links are the backup, well, just like 198 09:51.960 --> 09:52.800 with our system 199 09:52.800 --> 10:03.270 ID up here, we also have a port ID system where each port ID has a priority WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 199 09:52.800 --> 10:03.270 ID up here, we also have a port ID system where each port ID has a priority 200 10:03.270 --> 10:04.720 value and 201 10:04.720 --> 10:06.320 then an individual ID value. 202 10:06.320 --> 10:09.520 And this combines to give us the port ID. 203 10:09.520 --> 10:16.920 So this priority value is also 3278, 3278. 204 10:16.920 --> 10:21.600 And so if all of them are tied, it's just going to pick whichever ports have 205 10:21.600 --> 10:22.360 the lowest 206 10:22.360 --> 10:25.560 priority because once again, the lowest wins. 207 10:25.560 --> 10:28.280 So if I want to change this, I want to control this. 208 10:28.280 --> 10:32.410 Maybe I've got specific line cards in these chassis switches and I want to make WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 208 10:28.280 --> 10:32.410 Maybe I've got specific line cards in these chassis switches and I want to make 209 10:32.410 --> 10:33.960 sure that 210 10:33.960 --> 10:38.560 I don't just put all of the active ports on one of the line cards, for example, 211 10:38.560 --> 10:38.760 then I 212 10:38.760 --> 10:44.290 can change the port priority in order to more favorably choose some of those 213 10:44.290 --> 10:45.040 links over 214 10:45.040 --> 10:46.400 others. 215 10:46.400 --> 10:48.600 This is a little bit advanced configuration. 216 10:48.600 --> 10:52.350 We don't see this a lot in production networks, but it is good at least to 217 10:52.350 --> 10:53.280 plant that seed 218 10:53.280 --> 10:55.400 that those configurations exist. 219 10:55.400 --> 10:59.000 Meanwhile, the scope of the conversation is going to be a little bit more 220 10:59.000 --> 11:00.200 focused up here WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 220 10:59.000 --> 11:00.200 focused up here 221 11:00.200 --> 11:03.790 with making sure that we can bring our LACP connections online and then just 222 11:03.790 --> 11:04.400 generally 223 11:04.400 --> 11:09.090 understanding operationally how LACP behaves as well as the advantages we have 224 11:09.090 --> 11:09.600 by using 225 11:09.600 --> 11:11.320 it over static configuration.