11.1 EtherChannel

EtherChannel
Etherchannel is a link aggregation technology used in switches. Negotiations required

for link aggregation are dynamically provided by protocols. Multiple ports can be
represented as a single port with Etherchannel technology used to increase bandwidth.
It is possible to combine up to 8 ports using this technology. Etherchannel technology
physically has more than one port, but logically there is only one port. Normally, if more
than one port is used between the switches, a loop occurs, but STP (Spanning Tree
Protocol) prevents this loop formation. With this technology, the ports will logically
appear as a single port, so STP will not do any blocking.
Etherchannel provides redundancy. Redundancy is the continuation of the transmission

over other connections if one of the connections does not work. One of the important
points to note is that the ports are set at equal speeds, and another is that the combined
ports are in the same virtual local area network (vlan). If ports are used as trunks, they
must have the same native vlan. Packets are forwarded from a specific port as a result
of the hashing algorithm used. Algorithm, source mac address, destination mac address
or both; It can use source ip address, destination ip address, or both, or tcp/udp port
numbers. The most important aspect of this technology is that it increases the
bandwidth. Bandwidth can increase up to 800 Mbit/s, 8 Gbit/s or 80 Gbit/s with the use
of maximum 8 active ports.
In Etherchannel, switches can enable link configurations to be done dynamically. Two

protocols are used for this: PAgP (Port Aggregation Protocol) and LACP (Link
Aggregation Control Protocol). PagP is a Cisco device-specific protocol, while LACP is
a device-independent standard protocol.
LACP and PAgP protocols
These two protocols are functionally the same. The work of the two protocols is very
similar. These protocols make multiple physical connections look like a single line.
LACP (Link Aggregation Control Protocol) is an industry standard protocol and
standardized with the IEEE 802.3ad code. It can run on devices of all network
manufacturers. PAgP (Port Aggregation Protocol) is a Cisco proprietary protocol and
only works on Cisco devices. In PAgP developed by Cisco, packets are exchanged
between two switchers over ports with Etherchannel capability. In this way, the port is
compared by learning the group capabilities and its neighborhoods are determined.
PAgP can be configured in two ways as active and passive mode. Switches configured
in active mode send PAgP packets to remote switches to establish Etherchannel.
Switches configured in passive mode will only start PAgP packet exchange if a remote
device requests an Etherchannel creation.
Line aggregation technology is commonly used between core layer devices or in server-
to-switch connections. Using it between main tier devices provides both overall speed
increase and redundancy. In case of a problem in one of the lines, one of the passive
lines can be switched to data communication without waiting. In the case of using STP,
a certain period of time must pass for the line to open, but during this time, data losses
that cannot be compensated at the main layer may occur.
PAgP packets go through the ports created for Etherchannel on the switches. With
these packets, neighbors are defined, port groups are learned, and the switch compares
with its own information. This protocol also regulates Etherchannel; that is, if a port's
vlan information, speed or duplex mode has changed, it reconfigures them for other
ports.
LACP, on the other hand, is a standards-based protocol alternative to PAgP. LACP

packets are sent over Etherchannel ports. Neighbors such as PAgP are defined, port
groups are learned and comparisons are made with their own information.
When configuring Etherchannel, a protocol must be determined and assigned to its own
port for a negotiation on the switch to be Etherchannel.
The System priority value can be between 1 and 65,535, by default it is 32,768. If this
value is not set in the switches, it is determined which one will do the job of determining
the roles by looking at the mac addresses. The one with the lowest mac address value
will be selected.
More than eight ports can be assigned to Etherchannel. When choosing, the lowest port
priority values are checked. The extra ones will stay in standby state and will be
activated in case of a problem with other ports. Port priority values can also take a value
between 1 and 65535. This value is 32768 by default. If these values are equal, the
selection is made by looking at the lowest port number.
The point to be noted in the configuration on the screen is that the ports between gig
2/15– 8 and gig 3/5– 8 are not assigned priority. Then the default values will be used.
The default value is 32768, and since this value is greater than 100, these ports will
remain in standby.
After running the "show etherchannel summary" command, the assigned ports for the
groups are displayed.
With the “show etherchannel port” command, the mode of the ports, the protocol used
and the status of the ports are displayed.
"show etherchannel detail" gives detailed information about Etherchannel

configuration.
"show {pagp| lacp} neighbor" shows each port's Etherchannel neighbors.

11.1 EtherChannel

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EtherChannel

Etherchannel is a link aggregation technology used in switches. Negotiations required

Etherchannel provides redundancy. Redundancy is the continuation of the transmission

In Etherchannel, switches can enable link configurations to be done dynamically. Two

LACP, on the other hand, is a standards-based protocol alternative to PAgP. LACP

"show etherchannel detail" gives detailed information about Etherchannel

"show {pagp| lacp} neighbor" shows each port's Etherchannel neighbors.

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