Ether Channel - Layer 2

- Bundeling multiple physical link into logincal link is called ether channel and logical link is called port-channel.
- Interface no. is thet when we create bundeling, the group number given is called interface number.
- 8 link maximum can be bundle.
- There are multiple benefits of ehter channel. When bundeling is done throughput is increased, resilency (when primary link goes down secondary comes up at the same time without taking any time) and load balancing is done automatically.

Ether channel
There are few requirement to form Ether Channel, parameters must match on all port of same switch, it does not check for neighbour.

- Speed must match
- Duplex must match
- Ether standard must be same
- Allowed vlan must match
- Native vlan must match
- If port are access then, must be member of same vlan

There are 2 Method to configure Ether Channel
1. Static

- Static mode is also called ON mode
- Ether channe, is not negotiated
- Statically configured
- No packets are exchanged
- Link can be buldle upto 8

2. Dynamic
Dynamic method further have 2 way to configure ether chhannel
A. PAGP
- Cisco Properity
- it has 2 sub mode Silent and Nonsilent
- can bundle 8 link
- system priority is 32768
- It has 2 mode Auto(packet send) & Desirable(wait for packet)

B. LACP
- Open standard
- it has 2 mode Active(lacp packet send and initation) & Passive (no packet send and wait for packet and initation)
- can bundle 16 link where 8 link work at a time and 8 as backup
- system priority is 32768


Ether Channel Configuration

Ether channel
Sw1(Config)#interface range int [f0/0-4]
Sw1(config)#switchport mode trunk
Sw1(config)#channel-group [1] mode [Auto]

In above f0/0-4 is interface range that you want to bundle
1 is the channel-group number which represents the interface number
Auto is the mode of etherchannel. You can choose from ON mode(static), auto/desirable(PAGP) and active/passive(LACP)

Sw2(Config)#interface range int [f0/0-4]
Sw2(config)#switchport mode trunk
Sw2(config)#channel-group [1] mode [desirable]


Ether Channel Mis-Configuration guard

Port-channel or logical interface has a Mac address and while sending Data it uses single MAc address of Logical interface which can be any single physical interface MAC address. In cisco it is default enabled.

While configuring port-channel, if one switch is configured ether channel and another is not, Switch 1 will send all control plain traffic with same Mac and it will think that it will receive all traffic with same MAc address but in switch 2 no ether channel is configured so switch 1 will receive with different MAc address. So, while happening this Switch1 will put it'same alll port into Error-disalbe mode.

So, it is preferred to be configured etherchannel after shutdown neighbour's interface.


Ether Channel Load Balancing and Algorithm / Click here. . .