PAGP and LACP Protocol - Ether Channel with Computer Network

Here I am going to discussion about Ether-Channel standards name as PAgP and LACP protocol. So, first of all I am giving you some details for what is Ether-Channel.

What is Ether-Channel?

Ether-channel port channel is the way to connect two different switches with two or more links and make them bundled in such a way that it looks like to be a single link.It is used to provide high speed links and redundancy. Maximum of 8 links can be aggregated to form a single logical link.

Ether Channel

PAgP Protocol:

PAgP is a Cisco proprietary negotiation protocol. Port Aggregation Protocol is used to achieve the same goal as LACP. also it is used for the automated, logical aggregation of Ethernet switch ports, Which known as an Ethernet Channel.

This protocol over Static configuration is that is one, it does a configuration check on participating interfaces, as well as confirms that the neighboring interfaces are also using PAgP. That means that it guarantees that interfaces that don’t have similar configurations will not participate, and we won’t get an accidental switching loop.

There are below modes of PAgP:

Auto mode:
It passively negotiates PAgP aggregation. If the remote end of the link is also configured with Auto mode, a PAgP EtherChannel will not form. Auto side is waiting for negotiation to start from the other end.

Desirable mode:

With this mode the negotiation will be initiated by sending the special frames to form Ether-channel with the other end.

ON mode:

In this mode, the interface will be a part of EtherChannel but no negotiation takes place.

OFF mode:

No EtherChannel configured on the interface.

LACP Protocol:

LACP is a Standards-based (IEEE 802.3ad) negotiation protocol. Link Aggregation Control Protocol, is used to dynamically build an Ether-channel.

Link aggregation protocols. Before the standardization of LACP, Cisco developed an option called Port Aggregation Protocol (PAgP) on some Cisco switches. Other vendors have similar pre-standard protocols.

Importantly, LACP typically applies to strategies that bundle individual links of Ethernet connections, and not wireless transfers.

Link aggregation is a way of bundling a bunch of individual (Ethernet) links together so they act like a single logical link.

If you have a switch with a whole lot of Gigabit Ethernet ports, you can connect all of them to another device that also has a bunch of ports and balance the traffic among these links to improve performance.

Another important reason for using link aggregation is to provide fast and transparent recovery in case one of the individual links fails.

Terminology of Link Aggregation:

• The active monitoring protocol that allows devices to include or remove individual links from the LAG is called Link Aggregation Control Protocol (LACP).
  
• A group of ports combined together is called a link aggregation group, or LAG. Different vendors have their own terms for the concept. A LAG can also be called a port-channel, a bond, or a team.
  
• The rule that defines which packets are sent along which link is called the scheduling algorithm.

Active:

The active end of the group sends out a LACP frame and initiates the negotiation to form the Ether-channel. Both ends could be active and the result would be the same.

Passive:

Passive Mode does not initiate the negotiation. It just responds to LACP packets initiated by other end. So if both ends were passive, the Ether-channel would not be formed.

ON:

In this mode, the interface will be a part of EtherChannel but no negotiation takes place.

OFF:

No EtherChannel configured on the interface.