Cisco Tips: Etherchannel

Cisco Tips: Etherchannel

// Etherchannel is basically grouping 2 (SwitchB& SwitchC) or more physical
// (data - network)
// channels into 1 logical channel.


                              // Channels ( ~~~)
//    -------------------                                     -------------------
//    [  SwitchB ]    ~~~~~~~~~~       [  SwitchC ]
//    -------------------    ~~~~~~~~~~      ------------------- 


=====================================
// SwitchB

SwitchB> enable

SwitchB# configure terminal
Enter configuration commands, one per line. Ends with CNTL/Z.

// select fastEthernet 0/1 & 0/2

SwitchB(config) # interface range fastEthernet 0/1 - 2

// Create Etherchannel 1
// This Ehterchannel number needs to be the same on local switch (SwitchB)
// but can be different on the neighbour switch  (SwitchC)

// LACP is the IEEE 802.3ad spec
// PAgP is Cisco proprietary spec

SwitchB(config-if-range)# 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

// Port channel is Etherchannel

SwitchB(config-if-range)# channel-group 1 mode active
Creating a port channel interface Port channel 1

========================================

// SwitchC

SwitchC> enable

SwitchC# configure terminal

SwitchC(config) # interface range fastEthernet 0/1 - 2

// You can also use a different channel number (E.g.: 2 ) or
// even use the passive command (instead of active command)

SwitchC(config-if-range)# channel-group 1 mode active

// Etherchannel is up
*Mar 1 00:32:30 %LINEPROTO-5-UPDOWN: Line protocol on Interface  Port-channel1, changed state to up




SwitchC(config-if-range)# exit

SwitchC(config)# exit

SwitchC# show ip interface brief

// Logical Etherchannel Port-channel1

Interface          IP-Address  OK?  Method  Status  Protocol
Port-channel1  unassigned  YES  unset     up         up

SwitchC# show spanning-tree vlan 1

VLAN0001
   Spanning tree enabled protocol ieee
  
// Po1 Etherchannel is in Forwarding state

Interface     Role     Sts    Cost    Prio.Nbr    Type
---------------     --------    -----    -------    --------------     -------
Po1              Root    FWD  12       128.65       P2p

SwitchC# show etherchannel summary

// S - Layer2
// U - In use
// P - bundled in port-channel

Group   Port-Channel    Protocol   Ports
----------   ---------------------    --------------   ---------------------------------
1           Po1 (SU)           LACP        Fa0/1 (P)    Fa0/2 (P)

// See all info about port-channel 1

SwitchC# show interfaces port-channel 1