LACP lab doesn't works properly

[write2irfan]

I am preparing lab for CCNP Switch exam.

If I trace the packet , i found that ARP messages are passing from SwitchA to Switch B , but from SwitchB to SwitchA doesnt passes.

Host in SwitchB is no getting access to DHCP at router connected to SwitchA f0/1

SwitchB

show etherchannel summary

1      Po1(SU)           LACP   Fa0/3(P) Fa0/4(P) Po1(I)

SwitchA

show etherchannel summary

1      Po1(SU)           LACP   Fa0/3(P) Fa0/4(P)

below is my configuration

SwitchA
vtp domain DOMAIN
vtp mode transparent
!
spanning-tree mode rapid-pvst
spanning-tree vlan 11-13,21-23 priority 8192
!
vlan 11
!
vlan 12
!
vlan 13
!
vlan 21
name Marketing
!
vlan 22
name Sales
!
vlan 23
name Engineering
!
vlan 99
name TrunkNative
!
interface FastEthernet0/1 (connected with router )
switchport mode trunk
!
interface FastEthernet0/2 ( connected to a server which can get ip through DHCP in router)
switchport access vlan 21
switchport mode access
!
interface FastEthernet0/3
switchport trunk native vlan 99
switchport trunk allowed vlan 1,21-23,99
channel-protocol lacp
channel-group 1 mode active
switchport mode trunk
!
interface FastEthernet0/4
switchport trunk native vlan 99
switchport trunk allowed vlan 1,21-23,99
channel-protocol lacp
channel-group 1 mode active
switchport mode trunk
!
interface Port-channel 1
switchport trunk native vlan 99
switchport trunk allowed vlan 1,21-23,99
switchport mode trunk
!
interface Vlan1
no ip address
!

SwitchB
!
!
vtp domain DOMAIN
vtp mode transparent
!
spanning-tree mode rapid-pvst
!
vlan 21
name Marketing
!
vlan 22
name Sales
!
vlan 23
name Engineering
!
vlan 99
name TrunkNative
!

interface FastEthernet0/3
switchport trunk native vlan 99
switchport trunk allowed vlan 1,21-23,99
channel-protocol lacp
channel-group 1 mode passive
switchport mode trunk
!
interface FastEthernet0/4
switchport trunk native vlan 99
switchport trunk allowed vlan 1,21-23,99
channel-protocol lacp
channel-group 1 mode passive
switchport mode trunk
!
!
interface FastEthernet0/9
switchport access vlan 21
switchport mode access
spanning-tree portfast
!
interface FastEthernet0/10
switchport access vlan 21
switchport mode access
spanning-tree portfast
!
interface FastEthernet0/13
switchport access vlan 22
switchport mode access
spanning-tree portfast
!
interface FastEthernet0/14
switchport access vlan 22
switchport mode access
spanning-tree portfast
!
interface FastEthernet0/15
switchport access vlan 23
switchport mode access
spanning-tree portfast
!
interface FastEthernet0/16
switchport access vlan 23
switchport mode access
spanning-tree portfast
!

!
interface Port-channel 1
switchport trunk native vlan 99
switchport trunk allowed vlan 1,21-23,99
channel-group 1 mode passive
switchport mode trunk
!
interface Vlan1
ip address 192.168.1.11 255.255.255.0
!
ip default-gateway 192.168.1.1
!

[kcnajaf · Accepted solution]

Hi Irfan,

It looks like you have a wrong configuration on SwitchB. You dont put the channel group command under the actual port-channel interface itself. So please modify the configuraton as below and test the result for DHCP.

SwitchB

config terminal

interface Port-channel 1

no channel-group 1 mode passive

exit

Hope that helps

Regards

Najaf

Please rate when applicable or helpful !!!

[write2irfan]

Dear Najaf,

Great finding, IDHCP is working fine. Now i have a question Why LAB says make Switch B Interface port-cha 1 passive ?

[kcnajaf]

Hi Irfan,

If the Lab says that you to make interface as passive then this configuration has to be applied on the physcial interface and not on the port-channel interface, which would then be applied to the actual port-channel interface.

Hope that helps.

Regards

Najaf

Please rate when applicable or helpful !!!