Configuring an LACP EtherChannel

The industry standard LACP is used for link aggregation between multiple network nodes to ensure redundancy and availiability. This lab will discuss and demonstrate the configuration and verification of LACP EtherChannel.

Real World Application & Core Knowledge

In the world of EtherChannel technology there are two types of dynamic channel-group protocols, Port Aggregation Protocol (PAgP) which is a Cisco Proprietary protocol and Link Aggregation Control Protocol (LACP) which is the IEEE standard.

LACP uses two types of port modes; active and passive. LACP active mode unconditionally forms a LACP dynamic ether-channel whereas passive will only accept LACP negotiation attempts from a device set to active.

LACP is commonly used for Server NIC teaming with Broadcom or Intel NIC’s that support 802.3ad (LACP). This ensure that the server has two connections to a switch rather it is a stacked switch for redundancy or a blade chassis whereas the links are on different blades. If one nic goes down, connectivity to the server is not lost.

In this lab you will familiarize yourself with the following commands;

Command	Description
channel-group # mode active	This command when executed in interface configuration mode sets the channel-group number and LACP mode to aggressively attempt to form a LACP EtherChannel. If negotiations fail, the EtherChannel will not pass traffic.
channel-group # mode passive	This command when executed in interface configuration mode sets the channel-group number and LACP mode to listen for LACP packets but not aggressively and unconditionally form an EtherChannel using LACP.
show etherchannel summary	This command when executed from user or privileged mode will display a summary of local EtherChannel(s) properties such as the channel-group number, ports in the channel group, and the role the ports the play.
show etherchannel detail	This command when executed from user or privileged mode will display detailed information relating to the EtherChannel(s) local to the device.

Lab Prerequisites

Establish a console session with devices R1, R2, SW1 and SW2 than configure the devices respected hostname(s).
Configure VLAN 10 on both SW1 and SW2 and assign R1 and R2’s switch ports to VLAN 10.
Assign the IP address 10.1.1.1/24 to R1’s FastEthernet0/0 interface and 10.1.1.2/24 to R2’s FastEthernet0/1 interface.

Lab Objectives

Configure SW1’s Fa0/10, Fa0/11 and Fa0/12 interfaces to aggressively attempt to form a LACP EtherChannel.
Configure SW2’s Fa0/10, Fa0/11 and Fa0/12 interfaces to form a PAgP EtherChannel only when a device attempts to negotiate a LACP EtherChannel only.
Verify that interfaces Fa0/10, Fa0/11 and Fa0/12 on SW1 formed a LACP EtherChannel correctly.
Verify IP communication over the newly formed LACP Ether-Channel by pinging R2’s Fa0/1 IP Address from R1.

The NM-16ESW used in the Free CCNA Workbook GNS3 Topology for SW1, SW2 and SW3 does not support the Ether-Channel Link Aggregation Control Protocol (LACP). This Lab instructional section is demonstrated using two Cisco Catalyst 3560 Series switches.

Lab Instruction

Step 1 . – Configure SW1’s Fa0/10, Fa0/11 and Fa0/12 interfaces to aggressively attempt to form a LACP EtherChannel.

For this you’ll use the channel-group # mode active command in interface or interface range configuration mode as shown below;

SW1 con0 is now available



Press RETURN to get started.



SW1>enable
SW1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)#interface range f0/10 - 12
SW1(config-if-range)#no shut
SW1(config-if-range)#channel-group 1 mode active
Creating a port-channel interface Port-channel 1
SW1(config-if-range)#end
SW1#

Step 2. – Configure SW2’s Fa0/10, Fa0/11 and Fa0/12 interfaces to form a PAgP EtherChannel only when a device attempts to negotiate a LACP EtherChannel only.

For this you’ll use the channel-group # mode passive command in interface or interface range configuration mode as shown below;

SW2 con0 is now available



Press RETURN to get started.



SW2>enable
SW2#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
SW2(config)#interface range f0/10 - 12
SW2(config-if-range)#no shut
SW2(config-if-range)#channel-group 1 mode passive
Creating a port-channel interface Port-channel 1
SW2(config-if-range)#end
SW2#

Step 3. – Verify that interfaces Fa0/10, Fa0/11 and Fa0/12 on SW1 formed a LACP EtherChannel correctly.

To verify the EtherChannel LACP configuration you can use either the show etherchannel summary or show etherchannel detail command in user or privileged mode as shown below;

SW1#show etherchannel summary
Flags:  D - down        P - bundled in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        U - in use      f - failed to allocate aggregator

        M - not in use, minimum links not met
        u - unsuitable for bundling
        w - waiting to be aggregated
        d - default port


Number of channel-groups in use: 1
Number of aggregators:           1

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------
1      Po1(SU)         LACP      Fa0/10(P)   Fa0/11(P)   Fa0/12(P)   

SW1#

Step 4. – Verify IP communication over the newly formed LACP Ether-Channel by pinging R2’s Fa0/1 IP Address from R1 as shown below;

R1#ping 10.1.1.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.2, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/2/4 ms
R1#

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