Ether-Channel or "How we lied to Spanning-Tree"

previously we successfully set up inter VLAN routing and that's great in fact this PC still has the ability dipping the remote server on the 30 network and he's on the 10 network but here's our next challenge check this out what if we had 200 clients so this PC and a hundred and 99 more devices and they all are trying to use remote resources for example they all go out and they try to download this brand-new video off of this server well as they start pulling that video down across the network if they're all connected at 100 megabits per second and they're all full duplex because of the switch functionality we are gonna have a bottleneck right here now these two trunk links they're both 100 megabits but we're only using one of them and that's because spanning tree is avoiding a loop let's go verify that over here on switch 2 which is this guy right here the left switch let's just issue a show interface trunk and take a look at the trunking that's going on here it shows FA is 11 and 12 which is great that's perfect it's showing that we're not restricting any VLANs from crossing those trunks and currently we have V that's one that through three that we know about but check this out VLANs in spanning tree forwarding state and not pruned we are only forwarding for VLANs one and one through three on this top interface f8 1/11 and on the bottom interface fa 1/12 we're blocking now we could verify that further with a show spanning tree for VLAN two because we know B then to exists and we'll say we wanted to look at interface fa 1/12 and that shows us right here that it is indeed blocking and there's a lot of other spanning tree aspects that we could look at but for the moment we're just realizing that we have two physical interfaces but only one is being used now with fault tolerance that's a good thing because if the primary link fails the other link can pick up and start forwarding traffic that's great however most people if you pay for two you want to be able to use two for example if you buy two cars you want to be able to use two cars with firewalls and failover if you buy two firewalls it'd be great if you could have both of them working and they call that active active failover in the aasa' department for security and for fault tolerance well we can do the same thing here with spanning tree by tricking it what do you mean can you trick it we could tell the switches that instead of thinking of these two links as two separate physical paths we could tell spanning tree to consider them as one giant pipe called an ether channel now we can have layer two or layer three ether channels here we're gonna change these trunks from layer two trunks which they currently are and make the switches believe that they're one nice giant layer two ether channel so to pull this off we're going to neutralize effectively these two interfaces and set them back to their defaults and why do I do that every time as a precaution the reality is these two interfaces if they're both going to belong to a bundle on an ether channel bundle we want to go ahead and make sure they are identical so in that light just to err on the side of caution what I'm gonna do is I'm gonna do a default configuration apply the defaults to those two interfaces which will temporarily take out my trunking but then they'll both be exactly the same that's probably the number one cause when people try to set a third channel groups is that they don't have the two interfaces maybe once configured as an access port the others are configured as a trunk and as a result they don't pan out so the first thing we're gonna do is I'm gonna go in and do a default interface range for fast ethernet 1/11 through 12 and that'll take these two interfaces and they'll basically wipe them back to factory defaults now once that's done I'm then gonna go ahead and configure those two interfaces by specifying I'm gonna do a shutdown why because it's also helpful if we bring them down to our configuration then bring them up that's also helpful in getting the ether channel to work successfully the first time so here's the default interface range for those two interfaces and now that that's done we're gonna get a little you know Hisi message from the other side because we currently were Trunks and now we're not we're getting BPD's from the other side and that's okay so our next step is we're going now that they're all defaulted I'm gonna shut down those two interfaces and I'm gonna specify that they both belong to channel group number one now channel group number one doesn't exist yet I'm just creating it out of thin air and the various modes that are available we can have active or desirable and there's different channel negotiation protocols ones proprietary from Cisco called peg P ones an open standard called Lac P but here I'm just going to specify that I want it to be on I want them to be a part of Channel Group one and now we have this brand new interface and this interface is called interface port channel number one and we can treat it just like any other logical interface so if we want to configure a trunk because right now they're both a member of that port channel number one but they're not configured for trunking so to fix that we simply go back into interface port channel one which we actually haven't been into yet we created the port Channel Group one now we'll go into interface config for it and say switch port mode trunk so we've done two major things number one we specified that the two interfaces belong to port channel one and number two we told port channel one that is going to be a trunk and that's it now the rest of this is configuring the other sites so on switch one in the middle here we'd have to configure these two ports and these two ports as port channel groups we'll put these guys in port channel one and these guys in port channel two and then we'd also have to specify a port channel group four thirteen and fourteen over here on switch three on the far right now for me one of the toughest parts of configuring ether channel is to make sure I'm on the console the right device so the middle switch right here is what we're going to go ahead and configure next so oftentimes I'll put a config in I'll type away and I'm on the wrong device it's so painful I make extra care that I'm on the right device at the right time so this middle switch which is switch number one from our previous three videos we're going to go ahead and configure ports 11 12 13 and 14 as ether channel and we'll put 11 and 12 into port channel 1 and 13/14 to port channel 2 so pretty straightforward will go into configuration mode I'm gonna default the interfaces just to make sure that everything about what eleven twelve thirteen and fourteen is identical and once that's completely wiped out well then go to eleven and twelve will shut them down configure them to both be in Channel Group one and we'll specify mode on so we're not negotiating the channel group whatsoever and then I'm gonna do a no shut to bring them out of shutdown state only the same exact behavior for interface thirteen and fourteen except they're gonna put them in a different channel group I'm gonna put them in channel group two so just like creating sub interfaces you can use any number you want sing with channel groups you just pick them out of the air and use what you want to use so once we've assigned eleven twelve thirteen fourteen to channel groups we're then going to go into interface for port channel one tell it that we want it to be a trunk it contains interfaces eleven twelve and we're gonna do the same thing for port channel interface port channel two and tell it that we want it to be a trunk now these big blue circles are representing the logical interface or the port channel so we have a port channel between these two switches which is switched to and switch one and we have a port channel or will between switch one here and switch three on the right so switch one is done the only thing we have left is switch number three so let's go ahead and configure switch number three right now again getting to the right device is the half the battle so on switch three will go into configuration mode will default interfaces thirteen and fourteen that's these guys right here on this right switch and will shut down the interfaces just as a good practice see sometimes if it takes like five minutes to configure one side then you go to the other side you might have some error disabled States where the interface is timeout because they're trying to negotiate so doing a shut and a no shut gives you nice clean ability to work with that ether channel without out the risk of going into air disabled as it doesn't take as long if you do the shut and the no shut to turn them on at the same time in fact ideally we would configure both sides switch three and switch one and then a final step go back and just do a no shut at that moment on the interfaces involved so this looks pretty good what steps did we do besides defaulting the interfaces check it out all we really did is we told the interfaces that we want them to become members of the ether channel group so that is right here so right here this command channel group two mode on an interface configuration mode told these two interfaces they belong to the channel group and then we went into the interface for that channel group right here and we said we want you to go ahead and become a trunk right there so really we're looking at two basic commands interface config Channel group two mode on and then in the interface of the channel group itself switch port mode trunk so let's verify that this is all working let's go back to switch two now earlier let's scroll up and take a look at our show interface trunk from earlier earlier we had two trunk ports FA one slash eleven and twelve and we were only forwarding on eleven twelve wasn't being used because it was being blocked because of spanning tree if we now issue that same exact command I'll scope up in the history a little bit and show interface trunk take a look at this now it shows one logical interface that's our port channel group that we created it's trunking is on because we told it to trunk it's using a turtle at one cue the native VLAN hasn't changed from the defaults also take a look at this we are forwarding on port channel one and we're no longer blocking so spanning tree is forwarding and the internal load balancing is being done by the ether channel itself and one last thing here how do we verify the status of our ether channels because there's lots of variables that might cause these ether cells to not work well one test is we could verify that our pings still work through the network and hopefully they will so what happened here is that when we shut down those interface of those trunks and reset we must have lost some Arps on the virtual interfaces on this middle switch because that's what that represents right there if we did another ping she'd have 100% success also if we tried to ping right away spanning-tree this default configuration may take up to 30 seconds to allow frames to be forwarded on ports or trunks that just came up so another thing we can do to verify the ether Channel besides you know the functionality working is we can do a show ether channel summary and should we third channel summary will show us our a third channel groups here we have po1 for a port channel and we have su what does that mean capital S and capital you well the capital S is right here means it's a layer to ether channel as opposed to a layer 3 ether Channel and the u capital u means it's in use we're currently up and active and then we have the two members of that ether channel which are FA 1/11 and 1/12 and P represents in port channel meaning they're members of that port Channel and that's it so that's a great way to help I maximize the throughput on our networks and we could have multiple interfaces you get out 4 or 8 interfaces and they don't have to be just Fast Ethernet you could have gigabit interfaces so if you had eight gigabit links back-to-back between two switches you could effectively put them all into one bundle and have all that throughput as one logical pipe and spanning-tree wouldn't care a bit I appreciate you watching it's been a lot of fun and best wishes to everybody in your studies

Channel: Keith Barker - The OG of IT

Views: 38,633

Keywords: Cisco, Video, Training, cbt, etherchannel, ether-channel, switching, trunk, switched, L2_etherchannel

Id: lZZ5mYNgvYI

Length: 12min 53sec (773 seconds)

Published: Wed May 18 2011