What is EtherChannel and EtherChannel Negotiation Protocol

What is EtherChannel

The architecture of the port channel is used on the Cisco switches that allow physical Ethernet links grouping to create one logical Ethernet link to provide high-speed links and fault-tolerance between routers, switches, and servers.

EtherChannel Configuration

In Etherchannel, if we have two switches, and the server is connected to the first switch which is enough valuable due to very important data, and every switch which has an Ethernet technology is commonly based on FastEthernet which is 100 Mbps.

In the below image, a switch can transfer 100mbps data as well as a cabling connection will provide a 100 Mbps transfer rate. If we install cabling with more than 100 Mbps transfer rate, but the switch is working on 100 Mbps then not beneficial of installing more than 100 Mbps without making the switch more advanced. First, we have to make the switch advanced. If we manage everything properly then we can get a better speed and result.

Switch Speed

If the switch is 100 Mbps supported and the cabling transfer rate is 100 Mbps then it means both are working on FastEthernet technology, and in one second only 100 MB will be transferred from switch 1 to switch 2. If there are four computers connected to switch 2 and all four computers are working properly, then the 100 Mbps will be divided among those four computers by 25 Mbps per computer. If all four computers want to get data from switch 1 server then the 100 Mbps will be divided and each computer will get 25 Mbps data.

Switch Speed with more Computers

If we add one more computer to switch 2 according to our requirements and that computer need above 50 Mbps speed, but the previous four computers were running at 25 Mbps speed. Now the 100 Mbps link cannot fulfill our requirements so, what do we do? The FastEthernet cannot transfer above 100 Mbps data transfer.

Switch Speed with more Computers

The solution can be like this if we add two links for connectivity between both switches 1 and 2, and both links are FastEthernet then the transfer rates will be 100 Mbps on one link. One link would carry100 Mbps and the second link will also carry 100 Mbps data from switch to switch 2. So we will combine both physical wires into logically one link and this process is called EtherChannel.

Switch Speed with two wires

The benefit of combining both links is that if there are two computers connected to a switch 2, then every computer will receive 100 Mbps speed. Half traffic will go through the above link and half will be through the below link to switch 2, but the Cisco switch will be considering both wires as one cable. So the packets will be forwarded according to this consideration.

The process of combining the physical cables into a logical one group and producing the data through a load balancer is called Ether Channel. Suppose we add more two cables between switches 1 and 2, then it will become the second group because the first group is already created.

Switch Speed with more than two wires

But one group will be blocked or on standby when the Spanning Tree Protocol will be performed. So, the blocked group will be automatically up/active on that condition if the active link fails or got some problems. But keep in mind it seems that there are two physical cables but logically it is one cable or one port that will be considered that is shaped into one group.

Switch Speed Active links

The next thing is how many ports a switch can support? For example, if we add two cables and combine them into one group? Or add four cables and combines them into one group, or 6 or 8 cables? We can only add a maximum of 8 cables and combine them logically into the group but with more than 8 cables we can’t combine cables into one group. It means one group can have only 8 interfaces.

In other words, EtherChannel could provide you with 8 interfaces per time and each cable carry 100 Mbps. There 8 physical cables become 1 and 800mbps data will be transferred from switch 1 to switch 2. If the computers require high-speed data then we can manage through this procedure.

Switch Speed with 8 wires

Port Channel

Suppose we have a group 1 that contains two cables and in Ether Channel, we will call it interface port channel-1. So the identity of the group will be identified through interface port-channel 1. The same procedure will be applied to group 2, but the channel will be 2 and so on if we need more groups. But one group will have only 8 cables only.

Port Channel Group

EtherChannel Negotiation Protocol

1. Port Aggregation Protocol (PAgP)

If there are two Cisco switches on both sides then we will configure PAGP (Port Aggregation Protocol) on both switches. It means there are two or more switches and those switches are from Cisco then we will configure PAGP. PAGP is Cisco Proprietary that will work on only Cisco switches.

PAgP Configuration on Switch

2. Link Aggregation Control Protocol (LACP)

If there are other switches with Cisco in our company to create Ether Channel then we will configure LACP (Link Aggregation Control Protocol). The IEEE introduces the LACP (Link Aggregation Control Protocol) using the standard 802.3AD, which is an open standard for all. It means it will work on Cisco switches as well as will work on other switches. In LACP we can combine the maximum of 16 cables into one group but the combination of 8 cables is best suitable.