5.1.4 Lab - Tuning EtherChannel (Answers)

5.1.4 Lab – Tuning EtherChannel (Answers)

Topology

Objectives

Part 1: Build the Network and Configure Basic Device Settings
Part 2: Tune LACP-based EtherChannels
Part 3: Explore EtherChannel Load Balancing

Background / Scenario

The open standard Link Aggregation Control Protocol (LACP) is extremely flexible and offers robust options for maintaining an EtherChannel bundle. By default, LACP allows up to 8 active members and as many as 8 standby members in a single bundle. The minimum and maximum number of links can be controlled through configuration. In addition, the timing of LACP packets can be modified.

Both LACP and Cisco’s Port Aggregation Protocol (PAgP) support a wide variety of load-balancing algorithms, which help to maintain even distribution of the traffic load across an EtherChannel bundle.

In this lab, you will explore the tuning options for LACP, as well as the load-balancing options for EtherChannel in general.

Note: This lab is an exercise in tuning and optimizing EtherChannel and does not necessarily reflect networking best practices.

Note: The switches used with CCNP hands-on labs are Cisco 3650 with Cisco IOS XE release 16.9.4 (universalk9 image). Other routers and Cisco IOS versions can be used. Depending on the model and Cisco IOS version, the commands available and the output produced might vary from what is shown in the labs.

Note: Ensure that the switches have been erased and have no startup configurations. If you are unsure contact your instructor.

Instructor Note: Refer to the Instructor Lab Manual for the procedures to initialize and reload devices.

Required Resources

2 Switches (Cisco 3650 with Cisco IOS XE release 16.9.4 universal image or comparable)
1 PC (Windows with a terminal emulation program, such as Tera Term)
Console cables to configure the Cisco IOS devices via the console ports
Ethernet cables as shown in the topology

Part 1: Build the Network and Configure Basic Device Settings

In Part 1, you will set up the network topology and then tune and optimize EtherChannel.

Step 1: Cable the network as shown in the topology.

Attach the devices as shown in the topology diagram, and cable as necessary.

Step 2: Configure basic settings for each switch.

a. Console into each switch, enter global configuration mode, and apply the basic settings using the startup configurations below for each device.

Switch D1

hostname D1
banner motd # D1, Tuning EtherChannel #
spanning-tree mode rapid-pvst
line con 0
 exec-timeout 0 0
 logging synchronous
 exit
interface range g1/0/1-24, g1/1/1-4, g0/0
 shutdown
 exit
interface range g1/0/1-4
 switchport mode trunk
 no shutdown
 exit

Switch D2

hostname D2
banner motd # D2, Tuning EtherChannel #
spanning-tree mode rapid-pvst
line con 0
 exec-timeout 0 0
 logging synchronous
 exit
interface range g1/0/1-24, g1/1/1-4, g0/0
 shutdown
 exit
interface range g1/0/1-4
 switchport mode trunk
 no shutdown
 exit

b. Set the clock on each switch to UTC time.

c. Save the running configuration to startup-config.

Part 2: Tune LACP-based EtherChannels

An EtherChannel bundle using LACP as its negotiation protocol can have as many as 16 assigned members, with 8 active ports passing traffic, and the other 8 ports on standby. The switches involved in a LACP bundle negotiate a master/slave relationship and the designated master switch makes the decisions on which members are active and which are in “hot standby” mode when the number of members in the bundle exceeds 8.

The minimum and maximum number of ports allowed to be involved in a port channel can be managed through configuration as well.

In this part of the lab, you will do just that. For the group of links connecting D1 and D2, you will set up an EtherChannel bundle using LACP as the negotiation protocol, with a minimum of 2 links and a maximum of 3. As a part of this configuration, you will control which switch is the master. Next, you will enable LACP fast packets, reducing the time out period from 30 seconds to 1 second.

Step 1: Configure master switch criteria.

Each switch connected using LACP has a system ID value. Those numbers are compared, and the switch with the lowest number is considered the master. The system ID value is a combination of a system priority that defaults to 32768 and the base MAC address. Unlike spanning tree, the priority value for LACP does not have be scaled by multiples of 4096.

a. Use the show lacp sys-id privileged EXEC command to see what the sys-id value is for D1 and D2. Based on the output shown below, we can deduce that D1 would be the bundle master if all default values remained unchanged.

D1# show lacp sys-id
32768, d8b1.9028.af80

D2# show lacp sys-id
32768, d8b1.905d.c300

b. On D2, modify the lacp sys-id by changing the system priority. Use the lacp system-priority value global configuration command to set the value to 1, and then verify that the value has been changed.

D2# config t
Enter configuration commands, one per line.  End with CNTL/Z.
D2(config)# lacp system-priority 1
D2(config)# exit

D2# show lacp sys-id
1, d8b1.905d.c300

Step 2: Configure bundle size and member preferences.

By default, interfaces are selected to be included in the active bundle based on their interface id. For a given configuration, the lower numbered interfaces are added to the bundle until the bundle has reached its maximum size. Any interfaces that remain are put in hot standby mode.

a. Issue the shutdown command for the interfaces connecting D1 and D2.

D2# config t
Enter configuration commands, one per line.  End with CNTL/Z.
D2(config)# interface range g1/0/1-4
D2(config-if-range)# shutdown

b. Configure the connections between D1 and D2 into a single LACP EtherChannel bundle. Use Channel Group number 12 and the Active mode. Configure the interfaces for LACP Fast.

D2(config-if-range)# channel-group 12 mode active
Creating a port-channel interface Port-channel 12

D2(config-if-range)# lacp rate fast

c. Issue the no shutdown command for the interfaces connecting D1 and D2.

D2(config-if-range)# no shutdown
D2(config-if-range)# exit

d. On D1 and D2, configure the port-channel 12 interface with a LACP minimum bundle size of 2 interfaces, and the maximum bundle size of 3 interfaces.

Note: The maximum value is only required on the master switch. Configuring it on both sides of the bundle is a best practice that may help with troubleshooting.

D2(config)# interface port-channel 12
D2(config-if)# port-channel min-links 2
D2(config-if)# lacp max-bundle 3
D2(config-if)# end

e. Verify that the EtherChannel bundle has formed and take note of the ports that are included versus the port that is in hot standby mode.

D2# 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

        A - formed by Auto LAG


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

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
12     Po12(SU)        LACP        Gi1/0/1(P)    Gi1/0/2(P)    Gi1/0/3(P)    
                                   Gi1/0/4(H)

f. Verify the mode, state and rate of LACPDU being sent for port members.

D2# show lacp internal
Flags:  S - Device is requesting Slow LACPDUs
        F - Device is requesting Fast LACPDUs
        A - Device is in Active mode       P - Device is in Passive mode

Channel group 12
                            LACP port     Admin     Oper    Port      Port
Port      Flags   State     Priority      Key       Key     Number    State
Gi1/0/1   FA      bndl      32768         0xC       0xC     0x102     0x3F
Gi1/0/2   FA      bndl      32768         0xC       0xC     0x103     0x3F
Gi1/0/3   FA      bndl      32768         0xC       0xC     0x104     0x3F
Gi1/0/4   FA      hot-sby   32768         0xC       0xC     0x105     0xF

Part 3: Explore EtherChannel Load Balancing

The load balancing method used to send traffic through an EtherChannel is a global setting on the switch. All EtherChannels on a given switch will use the method selected for that switch. The load balancing methods used at either end of an EtherChannel bundle do not have to match.

The available methods, as well as the default method used, varies by hardware platform. By default, Cisco Catalyst 3650 and Catalyst 2960 switches load-balance using the source MAC address.

D2# show etherchannel load-balance 
EtherChannel Load-Balancing Configuration:
        src-mac

EtherChannel Load-Balancing Addresses Used Per-Protocol:
Non-IP: Source MAC address
  IPv4: Source MAC address
  IPv6: Source MAC address

The full form of the command to show what interface the load-balancing algorithm will choose is show platform software fed etherchannel [switch switch-number] channel-group-number {group-mask | load-balance mac src-mac dst-mac [ip src-ip dst-ip [port src-port dst-port]]}. Select a channel-group and specify the source and destination address (in the form of a MAC, IP, or Port number) and the switch tells you what the exit port will be. The example that follows shows that traffic with the same source MAC always exits using the same interface.

D1# show platform software fed switch 1 etherchannel 12 load-balance mac 0050.0040.00af 0050.0040.00fa 
Dest Port: : GigabitEthernet1/0/1

D1# show platform software fed switch 1 etherchannel 12 load-balance mac 0050.0040.00af 0050.0040.00fb 
Dest Port: : GigabitEthernet1/0/1

D1# show platform software fed switch 1 etherchannel 12 load-balance mac 0050.0040.00bf 0050.0040.00fb
Dest Port: : GigabitEthernet1/0/2

Use this command on your switches to verify how the default load-balancing scheme is working, and then try out the other load-balancing mechanisms to see how the behavior changes.

End of document

Switch D1

D1# show run
Building configuration...

Current configuration : 9265 bytes
!
version 16.9
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
! Call-home is enabled by Smart-Licensing.
service call-home
no platform punt-keepalive disable-kernel-core
!
hostname D1
!
vrf definition Mgmt-vrf
 !
 address-family ipv4
 exit-address-family
 !
 address-family ipv6
 exit-address-family
!
no aaa new-model
switch 1 provision ws-c3650-24ts
!
login on-success log
!
license boot level ipservicesk9
!
diagnostic bootup level minimal
!
spanning-tree mode rapid-pvst
spanning-tree extend system-id
!
redundancy
 mode sso
!
transceiver type all
 monitoring
!
class-map match-any system-cpp-police-topology-control
  description Topology control
class-map match-any system-cpp-police-sw-forward
  description Sw forwarding, L2 LVX data, LOGGING
class-map match-any system-cpp-default
  description Inter FED, EWLC control, EWLC data
class-map match-any system-cpp-police-sys-data
  description Learning cache ovfl, High Rate App, Exception, EGR Exception, NFL SAMPLED DATA, RPF Failed
class-map match-any system-cpp-police-punt-webauth
  description Punt Webauth
class-map match-any system-cpp-police-l2lvx-control
  description L2 LVX control packets
class-map match-any system-cpp-police-forus
  description Forus Address resolution and Forus traffic
class-map match-any system-cpp-police-multicast-end-station
  description MCAST END STATION
class-map match-any system-cpp-police-multicast
  description Transit Traffic and MCAST Data
class-map match-any system-cpp-police-l2-control
  description L2 control
class-map match-any system-cpp-police-dot1x-auth
  description DOT1X Auth
class-map match-any system-cpp-police-data
  description ICMP redirect, ICMP_GEN and BROADCAST
class-map match-any system-cpp-police-stackwise-virt-control
  description Stackwise Virtual
class-map match-any non-client-nrt-class
class-map match-any system-cpp-police-routing-control
  description Routing control and Low Latency
class-map match-any system-cpp-police-protocol-snooping
  description Protocol snooping
class-map match-any system-cpp-police-dhcp-snooping
  description DHCP snooping
class-map match-any system-cpp-police-system-critical
  description System Critical and Gold Pkt
!
policy-map system-cpp-policy
!
interface Port-channel12
 switchport mode trunk
 switchport nonegotiate
 port-channel min-links 2
 lacp max-bundle 3
!
interface GigabitEthernet0/0
 vrf forwarding Mgmt-vrf
 no ip address
 shutdown 
 negotiation auto
!
interface GigabitEthernet1/0/1
 switchport mode trunk
 switchport nonegotiate
 channel-group 12 mode active
 lacp rate fast
!
interface GigabitEthernet1/0/2
 switchport mode trunk
 switchport nonegotiate
 channel-group 12 mode active
 lacp rate fast
!
interface GigabitEthernet1/0/3
 switchport mode trunk
 switchport nonegotiate
 channel-group 12 mode active
 lacp rate fast
!
interface GigabitEthernet1/0/4
 switchport mode trunk
 switchport nonegotiate
 channel-group 12 mode active
 lacp rate fast
!
interface GigabitEthernet1/0/5
 shutdown
!
interface GigabitEthernet1/0/6
 shutdown
!
interface GigabitEthernet1/0/7
 shutdown
!
interface GigabitEthernet1/0/8
 shutdown
!
interface GigabitEthernet1/0/9
 shutdown
!
interface GigabitEthernet1/0/10
 shutdown
!
interface GigabitEthernet1/0/11
 shutdown 
!
interface GigabitEthernet1/0/12
 shutdown
!
interface GigabitEthernet1/0/13
 shutdown
!
interface GigabitEthernet1/0/14
 shutdown
!
interface GigabitEthernet1/0/15
 shutdown
!
interface GigabitEthernet1/0/16
 shutdown
!
interface GigabitEthernet1/0/17
 shutdown
!
interface GigabitEthernet1/0/18
 shutdown
!
interface GigabitEthernet1/0/19
 shutdown
!
interface GigabitEthernet1/0/20
 shutdown
!
interface GigabitEthernet1/0/21
 shutdown
!
interface GigabitEthernet1/0/22
 shutdown
!
interface GigabitEthernet1/0/23
 shutdown
!
interface GigabitEthernet1/0/24
 shutdown
!
interface GigabitEthernet1/1/1
 shutdown
!
interface GigabitEthernet1/1/2
 shutdown
!
interface GigabitEthernet1/1/3
 shutdown
!
interface GigabitEthernet1/1/4
 shutdown
!
interface Vlan1
 no ip address
 shutdown
!
ip forward-protocol nd
ip http server
ip http authentication local
ip http secure-server
!
control-plane
 service-policy input system-cpp-policy
!
banner motd ^C D1, Tuning EtherChannel ^C
!
line con 0
 exec-timeout 0 0
 logging synchronous
 stopbits 1
line aux 0
 stopbits 1
line vty 0 4
 exec-timeout 0 0
 privilege level 15
 password cisco123
 logging synchronous
 login
line vty 5 15
 login
!
end

Switch D2

D2# show run
Building configuration...

Current configuration : 9210 bytes
!
version 16.9
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
! Call-home is enabled by Smart-Licensing.
service call-home
no platform punt-keepalive disable-kernel-core
!
hostname D2
!
vrf definition Mgmt-vrf
 !
 address-family ipv4
 exit-address-family
 !
 address-family ipv6
 exit-address-family
!
no aaa new-model
switch 1 provision ws-c3650-24ts
!
login on-success log
!
license boot level ipservicesk9
!
diagnostic bootup level minimal
!
spanning-tree mode rapid-pvst
spanning-tree extend system-id
!
lacp system-priority 1
!
redundancy
 mode sso
!
transceiver type all
 monitoring
!
class-map match-any system-cpp-police-topology-control
  description Topology control
class-map match-any system-cpp-police-sw-forward
  description Sw forwarding, L2 LVX data, LOGGING
class-map match-any system-cpp-default
  description Inter FED, EWLC control, EWLC data
class-map match-any system-cpp-police-sys-data
  description Learning cache ovfl, High Rate App, Exception, EGR Exception, NFL SAMPLED DATA, RPF Failed
class-map match-any system-cpp-police-punt-webauth
  description Punt Webauth
class-map match-any system-cpp-police-l2lvx-control
  description L2 LVX control packets
class-map match-any system-cpp-police-forus
  description Forus Address resolution and Forus traffic
class-map match-any system-cpp-police-multicast-end-station
  description MCAST END STATION
class-map match-any system-cpp-police-multicast
  description Transit Traffic and MCAST Data
class-map match-any system-cpp-police-l2-control
  description L2 control
class-map match-any system-cpp-police-dot1x-auth
  description DOT1X Auth
class-map match-any system-cpp-police-data
  description ICMP redirect, ICMP_GEN and BROADCAST
class-map match-any system-cpp-police-stackwise-virt-control
  description Stackwise Virtual
class-map match-any non-client-nrt-class
class-map match-any system-cpp-police-routing-control
  description Routing control and Low Latency
class-map match-any system-cpp-police-protocol-snooping
  description Protocol snooping
class-map match-any system-cpp-police-dhcp-snooping
  description DHCP snooping
class-map match-any system-cpp-police-system-critical
  description System Critical and Gold Pkt
!
policy-map system-cpp-policy
!
interface Port-channel12
 switchport mode trunk
 switchport nonegotiate
 port-channel min-links 2
 lacp max-bundle 3
!
interface GigabitEthernet0/0
 vrf forwarding Mgmt-vrf
 no ip address
 shutdown
 negotiation auto
!
interface GigabitEthernet1/0/1
 switchport mode trunk
 switchport nonegotiate
 channel-group 12 mode active
 lacp rate fast
!
interface GigabitEthernet1/0/2
 switchport mode trunk
 switchport nonegotiate
 channel-group 12 mode active
 lacp rate fast
!
interface GigabitEthernet1/0/3
 switchport mode trunk
 switchport nonegotiate
 channel-group 12 mode active
 lacp rate fast
!
interface GigabitEthernet1/0/4
 switchport mode trunk
 switchport nonegotiate
 channel-group 12 mode active
 lacp rate fast
!
interface GigabitEthernet1/0/5
 shutdown
!
interface GigabitEthernet1/0/6
 shutdown
!
interface GigabitEthernet1/0/7
 shutdown
!
interface GigabitEthernet1/0/8
 shutdown
!
interface GigabitEthernet1/0/9
 shutdown
!
interface GigabitEthernet1/0/10
 shutdown
!
interface GigabitEthernet1/0/11
 shutdown
!
interface GigabitEthernet1/0/12
 shutdown
!
interface GigabitEthernet1/0/13
 shutdown
!
interface GigabitEthernet1/0/14
 shutdown
!
interface GigabitEthernet1/0/15
 shutdown
!
interface GigabitEthernet1/0/16
 shutdown
!
interface GigabitEthernet1/0/17
 shutdown
!
interface GigabitEthernet1/0/18
 shutdown
!
interface GigabitEthernet1/0/19
 shutdown
!
interface GigabitEthernet1/0/20
 shutdown
!
interface GigabitEthernet1/0/21
 shutdown
!
interface GigabitEthernet1/0/22
 shutdown
!
interface GigabitEthernet1/0/23
 shutdown
!
interface GigabitEthernet1/0/24
 shutdown
!
interface GigabitEthernet1/1/1
 shutdown
!
interface GigabitEthernet1/1/2
 shutdown 
!
interface GigabitEthernet1/1/3
 shutdown
!
interface GigabitEthernet1/1/4
 shutdown
!
interface Vlan1
 no ip address
 shutdown
!
ip forward-protocol nd
ip http server
ip http authentication local
ip http secure-server
!
control-plane
 service-policy input system-cpp-policy
!
banner motd ^C D2, Tuning EtherChannel ^C
!
line con 0
 exec-timeout 0 0
 logging synchronous
 stopbits 1
line aux 0
 stopbits 1
line vty 0 4
 login
line vty 5 15
 login
!
end