Ether channel config

1.  Ether Channel
 Understanding EtherChannelConfiguration
 Types of Etherchannel
 Manual EtherChannel configuration
 EtherChannel – DynamicConfiguration
IEEE Link Aggregation Protocol (LACP) - Industry Standard
PortAggregation Protocol (PAGP)- Cisco Proprietary protocol
 Troubleshooting Ether Channel
Understanding Ether Channel
Port aggregation allows multiplephysicalports to be
bundled togetherto forma singlelogicalport.Theswitch and STP will treatthe
bundled ports as a singleinterface,eliminating thepossibility of a switching
loop.
EtherChannel is a portlink aggregation technologydeveloped by Cisco,which
provides fault-toleranthigh-speed linksbetween Switches,Routers,and Servers.
EtherChannel technology can beused to increasethebandwidth between two
devices thatsupportEther Channel technologyand Ether Channeltechnology
provides automaticrecovery for theloss of a link by redistributing theload across
the remaining links.

2. However, simply trunking twoor more ports between the switches will not
work, as this creates a switchingloop. One of two things willoccur:
 Spanning TreeProtocol (STP) will disableoneormoreportsto
eliminatetheloop.
 If STP isdisabled,theswitchingloopwill resultin an almost
instantaneous broadcaststorm, cripplingthenetwork
Thereare two issues with using only a single physical port for the trunk
connection:
 Theportrepresents a singlepointof failure.If theportgoesdown,
the trunk connectionis lost.
 Thus,theobviousbenefitsof addingredundancyto thetrunk
connectionarefaulttoleranceand increasedbandwidth, viaload
balancing
Portaggregation allows multiplephysical ports to be bundledtogetherto forma
singlelogicalport. Theswitch and STP will treatthebundled ports as a single
interface,eliminating thepossibility of a switching loop.
Cisco’s implementation of portaggregationis called Ether Channel.
EtherChannel supports Fast,Gigabit,and 10 GigabitEthernetports. Amaximum
of 8 activeportsaresupportedina singleEtherChannel.
Cisco IOS Release12.2SX supports a maximumof 128EtherChannels.You can
form an EtherChannel with up to eightcompatibly configured LAN ports on any
switching module.All LAN ports in each EtherChannelmustbethe samespeed
and mustall beconfigured as eitherLayer 2 orLayer 3 LAN ports.

3. Types of Ether channel
There are two methodsof configuring an EtherChannel:
 Manually
 Dynamically
Manually:
Manually configured EtherChannelports do notexchangeEtherChannel
protocol packets.A manually configured EtherChannel forms only when you
configureall ports in theEtherChannel compatibly.
Configurationof etherchannel manually:
Adding switch ports to a channel-group creates a logical port-channel interface.
This interfacecan be configured by referencing thechannelgroup number:
SWITCH A SWITCH B
SwitchA(config)# interface range gi0/1 – 4 SwitchB(config)# interface range gi0/1 - 4
Switch A(config-if)# channel-group1 mode on SwitchB(config-if)# channel-group 1 mode on
Changes madeto the logical port-channel interfaceareapplied to all physical
switch ports in thechannel-group:
Switch A(config)# interface port-channel 1
SwitchA(config-if)# switchport mode trunk
SwitchA(config-if)# switchport trunk allowed vlan 5-10
Switch A(config-if)# noshut
Switch B(config)# interface port-channel 1
SwitchB(config-if)# switchportmode trunk
SwitchB(config-if)# switchporttrunk allowedvlan5-10
Switch B(config-if)# noshut

4. EtherChannel – DynamicConfiguration
Cisco switches supporttwo dynamicaggregation protocols:
PAgP(PortAggregationProtocol) – Cisco proprietary aggregatin protocol.
LACP (Link AggregationControlProtocol) – IEEE standardized aggregation
protocol,originally defined in 802.3ad
PAgP(PortAggregationProtocol) PAgP is a Cisco-proprietary aggregation
protocol. PAgP supports theautomaticcreation of EtherChannelsby exchanging
PAgP packets between LAN ports. PAgP packets are exchanged only between
ports in autoand desirablemodes.
Desirable– activelyattempts to forma channel
Auto– waits fortheremote switch to initiatethechannel
A PAgP channel will formin thefollowingconfigurations
desirable >> desirable
desirable>> auto
SWITCH A SWITCH B
SwitchA(config)# interface range gi0/1 – 4 Switch B(config)# interface range gi0/1 - 4
Switch(config-if)#channel-protocol pagp Switch(config-if)#channel-protocol pagp
Switch A(config-if)# channel-group1 mode auto Switch B(config-if)# channel-group1 mode desirable
Switch A(config)# interface port-channel 1 switchB ----same like as above configuration.
SwitchA(config-if)# switchport mode trunk
SwitchA(config-if)# switchport trunk allowed vlan 5-10
Switch A(config-if)# noshut

5. EtherChannel – LACP
LACP is an IEEE standard aggregation protocol,and supports two modes.LACP
supports theautomaticcreation of EtherChannels by exchangingLACP packets
between LAN ports. LACP packets are exchanged only between ports
in passiveand activemodes.
Active–activelyattempts to form a channel
Passive– waits fortheremoteswitch to initiatethechannel
An LACP channel will formin thefollowingconfigurations:
Active== active
Active==passive
SWITCH A SWITCH B
SwitchA(config)# interface range gi0/1 – 4 Switch B(config)# interface range gi0/1 - 4
Switch(config-if)#channel-protocol lacp Switch(config-if)#channel-protocol lacp
Switch A(config-if)# channel-group1 mode active SwitchB(config-if)# channel-group 1 mode passive
Switch A(config)# interface port-channel 1
SwitchA(config-if)# switchport mode trunk
SwitchA(config-if)# switchport trunk allowed vlan 5-10
Switch A(config-if)# noshut
Switch B(config)# interface port-channel 1
SwitchB(config-if)# switchportmode trunk
SwitchB(config-if)# switchporttrunk allowedvlan5-10
Switch B(config-if)# noshut

6. Recall thata maximumof 8 active ports are supported in a singleEtherChannel.
LACP supports adding an additional8 ports into thebundlein a standbystate,to
replace an activeport if it goes down.
LACP assigns a numerical port-priority to each port, to determinewhich ports
become active in the EtherChannel.By default,thepriority is setto 32768,and a
lower priority is preferred. If there is a tiein port-priority,thelowest portnumber
is preferred.
To changetheLACP port-priorityto something otherthan default:
Switch(config)#interfacerangefa0/1-4
Switch(config-if)# lacpport-priority 100
Troubleshooting EtherChannel
To view status information on allconfiguredEtherChannels:
Switch# showetherchannel summary
Switch#showetherchannel portchannel
This exampleshows howto verifythe configurationof EtherChannel1
switch#showrunning interfaces port-channel1