The EtherChannel allows you to group (aggregate) several ports into one.
The phrase "Link Aggregate" often comes up in French technical jargon (Aggregation – Grouping elements). I would use the terminology "EtherChannel" because all CISCO documentation is in English and it is important to become familiar with English terminology.
Knowing that a good sketch is better than a long speech, let's go straight back to the subject:
We have a link between two switches at 100Mbps. Our switch only has ports in Fast Ethernet (100 Mbps).
We need a 400Mb/s connection. We just have to add three links between these switches!
Unfortunately my links don't want to go up… What for? Because our equipment considers this to be a network loop! The STP protocol retains only a functional interface. How do I do that?
Setting up etherChannel 🙂
The EtherChannel allows you to group physical interfaces into a group. This group will be seen as a virtual interface by our switch.
To put it simply, we have 8 Ports (4 right and 4 left) it must be:
– All identical (Ethernet or Fast Ethernet or GigaBitEthernet etc…)
– Equal number on both sides of our Etherchannel.
– The ports that want to aggregate the same switch is in the same "Channel-group"
If one of the links falls, the EtherChannel continues on 3 links!
The EtherChannel is limited to 8 interfaces
There are two Etherchannel protocols:
PAgP (Port Aggregation Protocol)
– CISCO Owner
– Two modes: (Auto / Desirable)
LACP (Link Aggregation Control Protocol)
– IEEE 802.3ad Standard
– Two modes: (Active/Passive)
Switch (config-if) channel-group 1 mode? active Enable LACP unconditionally auto Enable PAgP only if a PAgP device is detected desirable Enable PAgP unconditionally on Enable Etherchannel only passive Enable LACP only if a LACP device is detected
PAgP Configuration (CISCO)
Switch (config)#interface FastEthernet range 0/1 -4 Switch (config-range)#channel-group 1 mode [ on | Desirable | Auto ] Switch (config-range) #exit Switch (config)#interface port-channel 1 Switch (config-if)#description VERS-SWITCH-B Switch (config-if)#switchport trunk mode Switch (config-if)#switchport trunk encapsulation dot1q
LACP Configuration (IEEE)
Switch (config)#interface FastEthernet range 0/1 -4 Switch (config-range)#channel-group 1 mode [ on | Active | Passive ] Switch (config-range)#channel-protocol lacp Switch (config-range) #exit Switch (config)#interface port-channel 1 Switch (config-if)#description VERS-SWITCH-B Switch (config-if)#switchport trunk mode Switch (config-if)#switchport trunk encapsulation dot1q
The default protocol is pagP. To use the LACP protocol, we just have to tell our equipment with the lacp channel-protocol command
In order to balance the load on the physical interfaces participating in the EtherChannel, our Switches can distribute the frames to send according to several parameters:
– src-mac — MAC source address — Bits
– dst-mac — Mac destination address — Bits
– src-dst-mac — MAC address source and destination — XOR
– src-ip — IP source address — Bits
– dst-ip — IP address destination — Bits
– src-dst-ip —IP source and destination address (Default) — XOR
– src-port —Port source — Bits
– dst-port — Port destination — Bits
– src-dst-port —Source and destination port — XOR
The load balancing method changes this as follows:
Switch (config) port-channel load-balance src-dst-ip
Hoping this article has been helpful to you! Don't hesitate to let me know!!
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