3

I got two L3 switches (Cisco 3560) with no switcport ports connected to L2 switch (Cisco 2960). It used to work, but when I saved and restarted Packet Tracer -- all ports went into standalone mode. This is the configuration of ports:

Vlan-40-Main (L3):

interface Port-channel5
 no switchport
 ip address 192.168.100.7 255.255.255.0
!
interface FastEthernet0/1
 no switchport
 no ip address
 channel-group 5 mode active
 duplex auto
 speed auto
!
interface FastEthernet0/2
 no switchport
 no ip address
 channel-group 5 mode active
 duplex auto
 speed auto
!

Vlan-30-Main (L3):

interface Port-channel6
 no switchport
 ip address 192.168.100.6 255.255.255.0
!
interface FastEthernet0/1
 no switchport
 no ip address
 channel-group 6 mode active
 duplex auto
 speed auto
!
interface FastEthernet0/2
 no switchport
 no ip address
 channel-group 6 mode active
 duplex auto
 speed auto
!

Upper-Trunk2 (L2):

interface Port-channel1
 switchport mode trunk

interface Port-channel2
 switchport mode trunk

enter image description here

Group  Port-channel  Protocol    Ports
------+-------------+-----------+----------------------------------------------

1      Po1(SD)           LACP   Fa0/1(I) Fa0/2(I) 
2      Po2(SD)           LACP   Fa0/3(I) Fa0/4(I) 
3      Po3(SU)           LACP   Fa0/5(P) Fa0/6(P)
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1
  • 4
    This is a problem with Packet Tracer. PT is not a real simulator so it doesn’t faithfully duplicate how routers and switches operate.
    – Ron Trunk
    Commented Dec 29, 2021 at 13:29

1 Answer 1

Reset to default
3

You cannot connect a layer-3 channel to a layer-2 trunk channel because the layer-3 channel can only process the native VLAN unless you create subinterfaces for it. Remember that a layer-3 interface on a switch is basically the same as a router interface.

You need something like:

interface Port-channel5
 description Native VLAN
 no switchport
 encapsulation dot1Q <VLAN Number N> native
 ip address 192.168.100.7 255.255.255.0
!
interface Port-channel5.<VLAN Number X>
 description VLAN <VLAN Number X>
 encapsulation dot1Q <VLAN Number X>
 ip address <VLAN X IP address> <VLAN X Mask>
!
interface Port-channel5.<VLAN Number Y>
 description <VLAN Number Y>
 encapsulation dot1Q <VLAN Number Y>
 ip address <VLAN Y IP address> <VLAN Y Mask>
!
interface FastEthernet0/1
 no switchport
 no ip address
 channel-group 5 mode active
!
interface FastEthernet0/2
 no switchport
 no ip address
 channel-group 5 mode active
!
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7
  • I tried, but got invalid input error at port-channel subinterface number
    – EugeneKannou
    Commented Dec 29, 2021 at 15:40
  • You probably ran into a Packet Tracer limitation. We use port channel subinterfaces all the time. Packet Tracer is a tool to get you through the CCNA, and it does not support more advanced features of real IOS.
    – Ron Maupin ♦
    Commented Dec 29, 2021 at 15:41
  • Is there another way to do that? I have no choice to use another program :(
    – EugeneKannou
    Commented Dec 29, 2021 at 15:42
  • Either use something that supports more advanced features, or you can rent a rack of equipment (there are several vendors that do this) that you can access remotely to do configuration tests.
    – Ron Maupin ♦
    Commented Dec 29, 2021 at 15:45
  • The weird thing is that it works without subinterfaces until I restart the program...
    – EugeneKannou
    Commented Dec 29, 2021 at 15:45

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