Etherchannel ICND2 question

[Deleted User]

Well, today is my birthday and since I have nothing else to do and on Spring Break, might as well jump into ICND2 studies. So I am on Day 33 of CCNA in 60 days and I have a question about EtherChannel. I understand the different types PAgP and LACP and their different modes and that only 8 ports can be used and commands, however the overall concepts just seem a bit confusing. From my understanding, EtherChannel is combining multiple switch links for faster bandwidth using the channel-group command (so almost like a trunk port in theory to send all VLAN traffic to other switches?) and can be used in Spanning Tree to have multiple links in case 1 link goes in blocking mode? Can anyone clarify this and demystify this?

illuminus

I cannot answer your question. I just wanted to wish you a happy birthday!

[Deleted User]

Thanks man! It is alright.

Zartanasaurus

It's like taking a road with one lane northbound and expanding it to two. Any single car (a network flow) is still limited to 65 MPH, but now you can fit two cars simultaneously.

Your comparison to trunking is off. A trunk port is like the conveyor belt for checked baggage at the airport. You can have 50 different flights (vlans) that the bags belong to, but they all go on the same belt (physical port). They place a tag on your luggage so the people at the other end know where the bag goes.

[Deleted User]

So either way, the traffic gets to the destination just able to fit more traffic across the link without losing bandwidth on the link?

Jon_Cisco

It's probably best to think of it as what will happen when you exceed the bandwidth of the single link.

If you on 1gb link and you are pushing 2gb of data the bottleneck will disrupt traffic.

Now you bundle 2 links and you have an aggregate 2gb bandwidth so the 2gb data still maxes you out.

However if you bundled 4 links your only pushing half capacity with your same 2gb data.

Sorry so sloppy at work and in a hurry. Hope this is not to confusing.

Happy Birthday.

tecnodog7

Zartanasaurus Amazing example

fuz1on

Thanks for allowing me to learn about EtherChannel in such a more intuitive way (cars and conveyor belts).

Happy Birthday Day kMastaFlash!!! I hope you have a great one. Don't worry - CCNA will be the icing on the cake.

davenull

Zartanasaurus wrote: »

It's like taking a road with one lane northbound and expanding it to two. Any single car (a network flow) is still limited to 65 MPH, but now you can fit two cars simultaneously.

Your comparison to trunking is off. A trunk port is like the conveyor belt for checked baggage at the airport. You can have 50 different flights (vlans) that the bags belong to, but they all go on the same belt (physical port). They place a tag on your luggage so the people at the other end know where the bag goes.

Fantastic analogy.

I can only add that the cars going to the same destination will use the same lane. In other words, Etherchannel does not provide true load-balancing.

OfWolfAndMan

Zartanasaurus wrote: »

It's like taking a road with one lane northbound and expanding it to two. Any single car (a network flow) is still limited to 65 MPH, but now you can fit two cars simultaneously.

Your comparison to trunking is off. A trunk port is like the conveyor belt for checked baggage at the airport. You can have 50 different flights (vlans) that the bags belong to, but they all go on the same belt (physical port). They place a tag on your luggage so the people at the other end know where the bag goes.

Excellent explanation.

Looking at it from a design perspective, remember that STP may provide loop prevention, but it also uses as few links logically as possible. Any redundant links will be put into blocking mode. You're not necessarily wasting money having backup links, but wouldn't it be nice if you could use more of those links and increase overall local throughput?