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1 Boson NetSim Lab Manual

SWITCH Lab: EtherChannel Negotiation

Protocols Part II: LACP

ObjectiveYou will plan, implement, and verify Layer 2 EtherChannel con gurations in this lab by con guring EtherChannel

between two switches using the PAgP negotiation protocol.

Lab TopologyThe Topology diagram below represents the NetMap in the Simulator:

CSW1DSW1

PC1

ASW1

Gi0/1

Gi0/2

Gi0/1

Gi0/2

Fa0/1

Fa0/10

Fa0/1

Fa0/10

Fa0/11

Command Summary

Command Description

channel-group port-channel-number mode

{on | auto [non-silent] | desirable [non-

silent] on | active | passive}

assigns an Ethernet interface to an EtherChannel group

channel-protocol {lacp | pagp} con gures the EtherChannel negotiation protocol for the

interface

interface range fastethernet slot/starting-

port - ending-port

con gures a range of interfaces

interface type number changes from global con guration mode to interface

con guration mode

lacp port-priority priority-value con gures the LACP priority for the interface

lacp system-priority priority-value con gures the LACP priority for the system

show cdp neighbors displays information about directly connected neighbors

show etherchannel [channel-group-number]

{detail | load-balance | port | port-channel |

summary | protocol}

displays EtherChannel information for a channel

show interfaces [type number] displays the interfaces Data Link layer status; when the

type and number parameters are included, displays detailed

information about the speci ed interface

show interfaces trunk displays port and module interface-trunk information

show ip interface brief displays a brief summary of interface status and con guration

show running-con g displays the active con guration le

switchport mode {access | dynamic {auto |

desirable} | trunk}

con gures the virtual LAN (VLAN) membership mode of a port

switchport trunk encapsulation dot1q con gures trunk for 802.1Q encapsulation

Lab ID: 8.8K1112A195.SWP.1


Lab Tasks

Task 1: Plan EtherChannel Con gurations

This task involves planning Layer 2 EtherChannel con gurations using negotiation protocols. In this lab, you will

be assigning physical interfaces to a channel group and using LACP to form an EtherChannel between ASW1

and DSW1.

1. What command could you issue to determine the number of links that are available to form an

EtherChannel? ______________________________________________________________________

2. Which protocol is de ned in the IEEE 802.3ad standard, and when should it be used? ______________

3. Which modes does LACP support? List any factors that would determine which mode you would use.

__________________________________________________________________________________

__________________________________________________________________________________

4. How many interfaces can be bundled in an EtherChannel using LACP? What happens to additional

interfaces once this limit is met? ________________________________________________________

__________________________________________________________________________________

5. Can more than one EtherChannel protocol be used in the same EtherChannel? ___________________

6. What happens to the physical interfaces when you make a change to a port-channel interface? ______

__________________________________________________________________________________

Task 2: Review Initial Con gurations

This task involves performing Layer 2 EtherChannel con gurations.

1. Determine the number of links that can be con gured as part of the port-channel group.

2. Observe the line and protocol state of each interface on ASW1 and DSW1.

3. Verify that an active trunk link exists between ASW1 and DSW1. Which trunk encapsulation type are both

switches using? _____________________________________________________________________

4. When the lab is loaded, all 20 interfaces have identical con gurations. Why is this important to know?

__________________________________________________________________________________

Task 3: Con gure EtherChannel by Using LACP

This task involves con guring the appropriate interfaces to use LACP as the EtherChannel negotiation protocol.

1. Con gure the FastEthernet 0/1 - 10 interfaces of ASW1 and DSW1 to use LACP as the EtherChannel

negotiation protocol.


2. Con gure the FastEthernet 0/1 - 10 interfaces on ASW1 and DSW1 as members of channel-group 1 by

using the passive mode.

3. Verify that the new, automatically created Port-Channel 1 interface exists on ASW1 and DSW1.

4. Determine the administrative mode of the newly created port-channel interface.

5. Con gure the Port-Channel 1 interface to trunk unconditionally using 802.1Q as the trunk encapsulation.

6. Use the show etherchannel summary command to view details about the channel group. Are

FastEthernet 0/1 - 10 bundled in the port channel? If not, why? ________________________________

__________________________________________________________________________________

7. Con gure FastEthernet 0/1 - 10 on ASW1 to use LACP active mode.

8. Use the show ip interface brief command to verify that the line and protocol state of Port-Channel 1 are

both up.

9. Use the show etherchannel summary command to view details about the channel group. List any

interfaces that are not in a bundled state. What state are these interfaces in and why? ______________

__________________________________________________________________________________

10. Determine the LACP port priority for interfaces in the channel group.

Task 4: Con gure LACP Priorities

1. On ASW1, change the LACP port priority of FastEthernet 0/9 to 100.

2. Use the show etherchannel summary command on ASW1 to display details about the channel group. Is

FastEthernet 0/9 in a bundled state? _____________________________________________________

3. On ASW1, use the show etherchannel port command to display details about each interface that is a

member of a channel group, including the device ID of its partner. Repeat this step on DSW1. What is the

signi cance of the partner device ID? ____________________________________________________

__________________________________________________________________________________

4. Change the LACP system priority of ASW1 to 100.

5. Use the show etherchannel summary command on ASW1. Is FastEthernet 0/9 in a bundled state?

Have any interfaces changed to hot standby? ______________________________________________


Lab Solutions

Task 1: Plan Ethernet Con gurations

This task involves planning EtherChannel con gurations.

1. You should issue the show cdp neighbors command to determine the number of links that are available

to form an EtherChannel. EtherChannel requires a minimum of 2 links between devices.

2. Link Aggregation Control Protocol (LACP) is de ned in the Institute of Electrical and Electronics

Engineers (IEEE) 802.3ad standard. Because LACP is a standards-based protocol, it can be used

between Cisco and non-Cisco switches. Conversely, Port Aggregation Protocol (PAgP) is a Cisco

proprietary protocol and can only be used to create EtherChannels between Cisco switches. Either one

of these protocols will allow a switch to learn its partners capabilities and dynamically group identically

con gured interfaces into a single logical link.

3. LACP can be con gured in either active or passive mode. Active mode places an interface into a state

where it will initiate negotiation with its partner by sending out LACP packets. Passive mode places

an interface into a state where it will respond to LACP packets but not initiate any negotiation. Placing

an interface in passive mode will minimize LACP traf c; however, if both ends of a link are con gured

in passive mode, no negotiation can take place and the interface will not be bundled. The table below

describes the different modes of LACP and PAgP:

4. Both PAgP and LACP support up to 8 active links between devices in a negotiated channel. LACP allows

a maximum of 16 ports to be con gured in a channel, but only 8 can be active at any given time. Non-

active links in an LACP bundle are placed in hot standby mode, and if any active link becomes inactive,

one of the hot standby links will change to active mode and take its place in the channel.

LACP uses the port priority and port ID values to determine which hot standby port will become active.

The LACP port priority is set to 32768 by default for all interfaces; however, you can change this value

to specify which hot standby links become active rst. A lower LACP priority value will place an interface

ahead of others when active ports are being selected. If hot standby ports are con gured with the same

LACP port priority then ports with lower port numbers will be selected rst.


5. All ports in an EtherChannel must be con gured to use the same protocol: either PAgP or LACP, not both.

Additionally, all ports must be con gured with the same speed and duplex settings. Ports in an LACP

channel that are con gured for half-duplex mode are placed in a suspended state and not used in the

channel.

6. When you make a change to a port-channel interface, the changes are implemented on all physical

interfaces. Conversely, if you make a con guration change on a physical interface that is part of the

channel group, the change is not implemented on any of the other physical interfaces in the channel

group or the groups port-channel interface. Making a change to a physical interface might unbundle it

from the port channel and place it in a stand-alone state.

Task 2: Review Initial Con gurations

This task involves implementing the planned EtherChannel con gurations and enabling LACP as the negotiation

protocol.

1. By issuing the show cdp neighbors command on ASW1, you can determine that ports FastEthernet

0/1 - 10 form links to the FastEthernet 0/1 - 10 ports on DSW1. These 20 ports form 10 links that can be

con gured to form a channel group between ASW1 and DSW1. Below is sample output from ASW1:

ASW1#show cdp neighbors

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

S -Switch, H - Host, i - IGMP, r - Repeater

Device ID Local Intrfce Holdtme Capability Platform Port ID

DSW1 Fas0/1 129 T S 3550 Fas 0/1

DSW1 Fas0/2 129 T S 3550 Fas 0/2

DSW1 Fas0/3 129 T S 3550 Fas 0/3

DSW1 Fas0/4 129 T S 3550 Fas 0/4

DSW1 Fas0/5 129 T S 3550 Fas 0/5

DSW1 Fas0/6 129 T S 3550 Fas 0/6

DSW1 Fas0/7 129 T S 3550 Fas 0/7

DSW1 Fas0/8 129 T S 3550 Fas 0/8

DSW1 Fas0/9 129 T S 3550 Fas 0/9

DSW1 Fas0/10 129 T S 3550 Fas 0/10


2. You can infer from the output of the show cdp neighbors command that FastEthernet 0/1 - 10 are up

and connected to their respective DSW1 ports; however, to verify the line and protocol state, you should

use the show ip interface brief command. Below is a sample output from ASW1:

ASW1#show ip interface brief

Interface IP-Address OK? Method Status Protocol

Vlan 1 unassigned YES unset up up

FastEthernet0/1 unassigned YES unset up up











FastEthernet0/12 unassigned YES unset down down

3. You can issue the show interfaces trunk command to observe the trunk state and encapsulation type of

each port. All of the ports should display that they have negotiated 802.1Q encapsulation. Sample output

is shown below:

ASW1#show interfaces trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 desirable 802.1q trunking 1










4. It is important to know that all 20 interfaces have identical con gurations when the lab is loaded because

ports that form a channel group must have identical con gurations.


Task 3: Con gure EtherChannel by Using LACP

1. You should issue the following commands to con gure LACP as the negotiation protocol on the interfaces

that form the links between ASW1 and DSW1:

ASW1(config)#interface range fastethernet 0/1 10

ASW1(config-if-range)#channel-protocol lacp

DSW1(config)#interface range fastethernet 0/1 10

DSW1(config-if-range)#channel-protocol lacp

2. You should issue the following commands to add the interfaces of ASW1 and DSW1 to channel-group 1

and enable LACP passive mode:

ASW1(config-if-range)#channel-group 1 mode passive

DSW1(config-if-range)#channel-group 1 mode passive

3. You should issue the show interfaces port-channel 1 command to verify that the Port-Channel 1

interface exists on ASW1 and DSW1. Below is sample output from ASW1:

ASW1#show interfaces port-channel 1

Port-channel1 is down, line protocol is down

Hardware is EtherChannel, address is 000C.3267.4215 (bia 000C.3267.4215)

MTU 1500 bytes, BW 1000 Kbit, DLY 100 usec,

reliability 255/255, txload 1/255, rxload 1/255

Auto-duplex, Auto-speed

Encapsulation ARPA, loopback not set

ARP type: ARPA, ARP Timeout 04:00:00

Last input 02:29:44, output never, output hang never

Last clearing of show interface counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queuing strategy: fifo

Output queue :0/40 (size/max)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

269 packets input, 71059 bytes, 0 no buffer

Received 6 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

7290 packets output, 429075 bytes, 0 underruns

0 output errors, 3 interface resets

0 output buffer failures, 0 output buffers swapped out


4. You should issue the show interfaces port-channel 1 switchport command to determine the

administrative mode con gured on ASW1 and DSW1. The following is sample output from ASW1:

ASW1#show interfaces port-channel 1 switchport

Name: Po1

Switchport: Enabled

Administrative mode: dynamic desirable

Operational mode: trunk

Administrative Trunking Encapsulation: dot1q

Operational Trunking Encapsulation: dot1q

Negotiation of Trunking: On

Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Voice VLAN: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001

Protected: false

Appliance trust: none

5. Once you create a Port-Channel interface, all interfaces in the channel group are con gured from

the port-channel interface for the group. You should issue the following commands to change the

administrative mode to form a trunk unconditionally and force the encapsulation to 802.1Q on the Port-

Channel 1 interface of the switches:

ASW1(config)#interface port-channel 1

ASW1(config-if)#switchport trunk encapsulation dot1q

ASW1(config-if)#switchport mode trunk

DSW1(config)#interface port-channel 1

DSW1(config-if)#switchport trunk encapsulation dot1q

DSW1(config-if)#switchport mode trunk


6. Below is sample output of the show etherchannel summary command for both ASW1 and DSW1. From

this output, you can observe that the ags (DS) associated with the Port-Channel 1 interface indicate

that the port channel is down (D) and running in Layer 2 mode (S). The FastEthernet 0/1 - 10 interfaces

can be observed to be running in a stand-alone state (I). This means that the physical interfaces are

not bundled in the port channel and are sending traf c independently. In step 2, you con gured the ports

on ASW1 and DSW1 to use LACP passive mode. This means that neither end of the EtherChannel will

initiate sending LACP packets and successful EtherChannel negotiation cannot occur. Sample output is

shown below:

ASW1#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(DS) LACP Fa0/1(I) Fa0/2(I) Fa0/3(I) Fa0/4(I)

Fa0/5(I) Fa0/6(I) Fa0/7(I) Fa0/8(I) Fa0/9(I) Fa0/10(I)

DSW1#show etherchannel summary









d - default port


number of aggregators: 1


---------------------------------------------------------------

1 Po1(DS) LACP Fa0/1(I) Fa0/2(I) Fa0/3(I) Fa0/4(I)

Fa0/5(I) Fa0/6(I) Fa0/7(I) Fa0/8(I) Fa0/9(I) Fa0/10(I)


7. In order to successfully negotiate an EtherChannel using LACP, at least one end of the link should be

con gured to use active mode. You should issue the following commands on ASW1 to enable active

mode for interfaces FastEthernet 0/1 - 10:

ASW1(config)#interface range fastethernet 0/1 - 10

ASW1(config-if-range)#channel-group 1 mode active

8. You can verify that the line and protocol states of the Port-Channel 1 interface are both up using the

show ip interface brief command. Below is sample output from ASW1:

ASW1#show ip interface brief

Interface IP-Address OK? Method Status Protocol

Vlan 1 unassigned YES unset up up












FastEthernet0/12 unassigned YES unset down down

Port-channel1 unassigned YES unset up up

9. The output of the show etherchannel summary command should now indicate that the Port-Channel

1 interface is up. The (P) ag associated with the FastEthernet 0/1 - 8 interfaces indicates that these

interfaces are now bundled in the port channel. The (H) ag associated with FastEthernet 0/9 and

FastEthernet 0/10 indicates that these interfaces are in a hot standby state. The (US) ags for the Port-

Channel 1 interface indicate that the port channel is in use (U) and operating in Layer 2 mode (S). LACP

allows up to 8 ports to be active and the rest are placed in hot standby.










d - default port




---------------------------------------------------------------

1 Po1(US) LACP Fa0/1(P) Fa0/2(P) Fa0/3(P) Fa0/4(P)

Fa0/5(P) Fa0/6(P) Fa0/7(P) Fa0/8(P) Fa0/9(H) Fa0/10(H)

(continued on next page)


(continued from previous page)

DSW1#show etherchannel summary









d - default port




---------------------------------------------------------------



10. You should issue the show etherchannel port command to determine that all of the interfaces are

con gured with the default LACP port priority (32768), which causes LACP to select active interfaces

based on the lowest port number. The following is partial sample output from DSW1:

DSW1#show etherchannel port

Channel-group listing:

----------------------

Group: 1

----------

Ports in the group:

-------------------

Port: Fa0/1

------------

Port state = Up Mstr In-Bndl

Channel group = 1 Mode = Passive Gccchange = 0

Port-channel = Po1 GC = 0x00000101 Psuedo port-channel = Po1

Port index = 1 Load = 0x00 Protocol = LACP

Flags: S - Device is sending Slow LACPDUs F - Device is sending fast

LACPDUs.

A - Device is in active mode. P - Device is in passive mode.

Local information:

LACP port Admin Oper Port Port

Port Flags State Priority Key Key Number State

Fa0/1 SP bndl 32768 0x3 0x3 0x2 0x3C




Partners information:


Port Flags Priority Dev ID Age key Key Number State

Fa0/1 SA 32768 000C.3388.4866 20s 0x0 0x3 0x2 SA

Age of the port in the current state:

Port: Fa0/2

------------






LACPDUs.


Task 4: Con gure LACP Priorities

1. Use the following commands to change the LACP port-priority of FastEthernet 0/9 on ASW1. By

con guring a port priority lower than the other interfaces you can make sure that FastEthernet 0/9 is

selected as an active interface and not placed in hot standby. You can verify your con guration by issuing

the show etherchannel port command.

ASW1(config)#interface fastethernet 0/9

ASW1(config-if)#lacp port-priority 100

ASW1#show etherchannel port

Port: Fa0/9

------------


Channel group = 1 Mode = Active Gccchange = 0




LACPDUs.


Local information:



Fa0/9 SA hot-sby 100 0x3 0x3 0x10 0x3D







Fa0/9 SP 32768 000C.1380.3538 10s 0x0 0x3 0x10 SP

Age of the port in the current state:

2. The output of the show etherchannel summary command indicates that the FastEthernet 0/9 interface

is still in a hot standby state, even though you have changed the port priority so that it would be selected

to become active before the other interfaces. Sample output is shown below:










d - default port




---------------------------------------------------------------




3. LACP allows only one switch to make decisions about which interfaces are actively participating in the

EtherChannel. The LACP system priority and the device ID (switch MAC address) are used to determine

which switch is the decision maker. Both ASW1 and DSW1 are con gured with default LACP system

priority values (32768) so in this case the device with the lower device ID will be the decision maker. By

using the show etherchannel port command on ASW1, you can observe that the device ID of its partner

(DSW1) is 000C.1380.3538. The same command is used on DSW1 to observe that the device ID of

ASW1 is 000C.3388.4866. Since DSW1 has the lower device ID it will decide which interfaces are active,

regardless of the port priority con gurations on ASW1. Sample output is shown below:

ASW1#show etherchannel port


----------------------

Group: 1

----------

Ports in the group:

-------------------

Port: Fa0/1

------------


Channel group = 1 Mode = Active Gccchange = 0




LACPDUs.


Local information:



Fa0/1 SA bndl 32768 0x3 0x3 0x2 0x3D




Fa0/1 SP 32768 000C.1380.3538 24s 0x0 0x3 0x2 SP




DSW1#show etherchannel port


----------------------

Group: 1

----------

Ports in the group:

-------------------

Port: Fa0/1

------------






LACPDUs.


Local information:



Fa0/1 SP bndl 32768 0x3 0x3 0x2 0x3C




Fa0/1 SA 32768 000C.3388.4866 29s 0x0 0x3 0x2 SA

4. By changing the LACP system priority value on ASW1, you can make it the decision maker about active

ports in the EtherChannel. You should issue the following command on ASW1 to change the system

priority from 32768 (default) to 100:

ASW1(config)#lacp system-priority 100


5. The output of the show etherchannel summary command should now indicate that FastEthernet 0/9 is

bundled and FastEthernet 0/8 has been placed in hot standby. Sample output is shown below:










d - default port




---------------------------------------------------------------


Fa0/5(P) Fa0/6(P) Fa0/7(P) Fa0/8(H) Fa0/9(P) Fa0/10(H)


Sample Con guration Scripts

ASW1 ASW1 (continued)

ASW1#show running-config

Building configuration...

Current configuration : 1739 bytes

!

Version 12.3

service timestamps debug uptime

service timestamps log uptime

no service password-encryption

!

hostname ASW1

ip cef

!

ip subnet-zero

!

no ip domain-lookup

lacp system-priority 100

spanning-tree mode pvst

spanning-tree extend system-id

!

interface Port-channel1

switchport mode trunk

!

interface FastEthernet0/1


channel-protocol lacp

channel-group 1 mode active

!





!





!





!





!





!





!





!



lacp port-priority 100



!





!


!


!

interface Vlan 1

no ip address

no ip route-cache

!

ip classless

no ip http server


!

line con 0

line aux 0

line vty 0 15

!

no scheduler allocate

end

Copyright 19962012 Boson Software, LLC. All rights reserved. NetSim software and documentation are protected by copyright law.


DSW1 DSW1 (continued)

DSW1#show running-config

Building configuration...

Current configuration : 2318 bytes

!

Version 12.3

service timestamps debug uptime

service timestamps log uptime

no service password-encryption

!

hostname DSW1

ip cef

!

ip subnet-zero

!

no ip domain-lookup

spanning-tree mode pvst

spanning-tree extend system-id

!

interface Port-channel1

switchport trunk encapsulation dot1q


!





channel-group 1 mode passive

!






!






!






!






!






!






!






!






!






!


!


!

interface GigabitEthernet0/1



!

interface GigabitEthernet0/2



!

interface Vlan 1

no ip address

no ip route-cache

!

ip classless

no ip http server

!

line con 0

line aux 0

line vty 0 4

!

no scheduler allocate

end