EtherChannel Explained | Concept & Configuration

hey what's up guys welcome to sir pros in this video we're going to be talking about ether channels if you've seen the STP video you might recognize this diagram what we have here is three redundant switches they're redundant because if any one switch or cable fails the other two can still communicate we can take this redundancy further though instead of just having one cable between switches we can have multiple but as you can probably imagine this brings another set of challenges let's zoom in on the bottom two switches so I can show you what I mean okay so assuming you are familiar with STP you'll note that we essentially have a switching loop here so stp doing what it does best will block one of these ports but this isn't what we want we want to take full advantage of our extra cables and extra bandwidth so what we can do instead is group the ports together on each switch this is an Easter Channel the ether channel creates his own logical interface an STP will put this interface into the forwarding State now we can take full advantage of the extra cable and the extra bandwidth that comes with it if a jános will even load-balanced over each cable so now a hundred megabit Ethernet cable has become a 200 megabit Ethernet cable and if one cable is pulled out or it fails no problem if the channels will just keep using the remaining cables this stops STP from needing to reconverge anytime a cable fails or is pulled out once you find your way down the hall and to the rack you can replace the cable and everything is back to full speed again okay so some points on ether channels they act as one logical interface this allows traffic to keep flowing even when a cable is unavailable it's also a way to avoid sending the same data back down the other cable and causing a loop this is because a switch will not send data back through the same interface it received it on we only have two tables here but you could have up to eight parallel tables in one ether Channel there are three methods to configuring ether channels you can manually set it or you could use either pagp or LACP to negotiate whether or not to join an ether channel now it's recommended to use negotiation rather than statically assigning it this way you avoid any miss configuration and as you've already seen if a channels will load balance the traffic some requirements for ether channels to work you will need to make sure that all ports and nifa channel has the same duplex these days is usually full speed so you couldn't have some ports running out a hundred megabit and then some running out one gigabit that just won't work they all need to be either an access port or a trunk port you would usually be doing this on drunk ports it's worth noting if you do use an access port they need to be on the same VLAN if you use drunk ports they need to have the same allowed VLANs and the same native VLAN you also need the same STP interface settings such as port priority I mentioned that there are three choices when configuring ether channels you can either set it manually or use either link aggregation control protocol LACP or port aggregation protocol pagp to negotiate the ether Channel the reason is recommended to use negotiation rather than setting it manually is because you run the risk of miss configuration which could end up with one side using if the channels and the other side not this means that data could in theory be sent from one switch and then the other side could send it back on the other port in very specific situations you could end up with a switching loop and if you've seen the STP video we all know what switching loops do to your network the better option is to use either the Cisco proprietary protocol pagp or the I Triple E standard LACP to negotiate whether or not to become an ether Channel when configuring if the channels on the switch you will need to remember the key words and what they mean on both sides off the cable you will need to match these keywords with the protocol you were trying to use so if you use the on on keyword this was statically set the ether channel desirable desirable desirable is the proactive option for pagp it will reach out to the other side and say hey want to join my pagp ether channel desirable auto auto is the passive option for pagp it will respond to desirable port messages but a whimper in the work if you have an auto auto configuration both ports will just not speak to each other and know if their channel will form active active so active is the proactive option for LACP this is the same as desirable for pagp again it will reach out to the other side and try and form and eat the channel lastly active passive passive for LACP is the same as Auto for pagp it will respond to active port messages but it won't proactively try and form an ether channel so you can't have two passive ports or an ether channel just will not form so we'll go through a quick config demo but before we start though you're gonna see the terms channel group port channel and if the channel it can be a bit confusing at first but just think of all three as the same thing I'll open up my first switch enable configure terminal and I'll use the interface range command to select fastethernet 0/1 and to so the command we're going to use is channel group one which is the number of the ephah channel work rating this number needs to be the same on the local switch but can be completely different on the neighbor switch then we'll type mode and if I do the question mark command we can see the options that we looked at earlier for this example I'm going to use the active mode and create an LACP ether channel that's it for this rich I'll open up the neighbor do the same enable configure terminal let the interfaces using the range command and again I'll type the command channel group one mode active so it could have used a different channel number and I could also have used the passive mode command instead and it would have still worked we should now see our new ether channel come up Cisco will call this a port Channel there it is our port channel is now up I Lecter out of here and now run a show IP interface brief command you will see here way at the bottom that we have a Newport channel interface this is our logical ether Channel I can also run a show spanning-tree vlan1 command that STP is using the single port channel interface that is actually using two cables and has put it into a four-inch state another good show command is the show ether channels summary this will show us the port channel and which ports belong to it it also has some flags at the top which will tell us the state each port is it using this we can see that our port channel is a layer 2 and also it is in use very far fast ethernet ports are bundled in with a port channel if there's been some sort of miscommunication you can even run a show interfaces or channel one command to see all the information about this logical interface you may note here that the bandwidth shows two hundred megabit which is two times our hundred megabit cables the configuration really is that easy the challenge comes when you've configured it and it doesn't work this is usually down to some kind of miss configuration in this case what you would do is first check the right modes have been used then double check the requirements to make sure everything matches that's it through four channels as always if you've liked this video then let us know by liking leaving a comment and subscribing the feedback from you really is what keeps the videos coming thank you for watching you

Channel: CertBros

Views: 127,142

Keywords: etherchannels, etherchannel, cisco etherchannel, etherchannels explained, etherchannel explained, cisco, ccna, ccent, how to configure etherchannel, how to configure cisco etherchannel, stp etherchannel

Id: j6-kadxwIFQ

Length: 11min 17sec (677 seconds)

Published: Sun Nov 26 2017