09-28-2017 01:54 PM - edited 03-08-2019 12:12 PM
I have two 3560s that are trunked together with five vlans allowed. Each vlan is assigned an IP address. Ping works between the two 3560s for each vlan. There is an identical setup for two 3650s and ping works. But if the trunk is between a 3560 and a 3650 ping does not work. What am I missing?
3560 config
interface GigabitEthernet0/23
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 100,110,200,210,700
switchport mode trunk
!
interface GigabitEthernet0/24
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 100,110,200,210,700
switchport mode trunk
!
interface Vlan100
ip address 10.0.0.1 255.255.255.128
!
interface Vlan110
ip address 10.50.0.1 255.255.255.128
!
interface Vlan200
ip address 10.10.0.1 255.255.255.128
!
interface Vlan210
ip address 10.60.0.1 255.255.255.128
!
interface Vlan700
ip address 10.80.0.1 255.255.255.224
3650 config
interface GigabitEthernet1/0/23
switchport trunk allowed vlan 100,110,200,210,700
switchport mode trunk
!
interface GigabitEthernet1/0/24
switchport trunk allowed vlan 100,110,200,210,700
switchport mode trunk
The vlan section is the same for all devices
09-28-2017 03:01 PM
09-28-2017 03:11 PM
09-29-2017 08:21 AM
Do you have an access port in the up state in each of those VLANs on either of the switches? If you don't have a device active in the VLAN the SVI won't be up, and therefore, not pingable.
Check to see if your protocol is up on the VLANs. If protocol is down, then try assigning a port to one of the vlans (switchport access vlan ##) and connect a device to it.
DS1-0694-M1#show ip int brief | in Vlan Interface IP-Address OK? Method Status Protocol
Vlan1 unassigned YES NVRAM administratively down down Vlan10 10.1.1.1 YES NVRAM up up Vlan100 10.1.2.1 YES NVRAM up up
10-03-2017 06:46 AM
Finally figured it out thanks to everyones suggestions on what to look at. First I must apologize since the posted configurations worked. It is when a port-channel was added to make the two connections act at one that it lost connectivity. The additional configuration is:
interface port-channel 1
switchport trunk encapsulation dot1q ! this is only on the 3560
switchport trunk native vlan 98
switchport trunk allowed vlan 10,11,20,21,70
switchport mode trunk
Ports 23 and 24 for both 3560 and 3650 had the following line added
channel-group 1 mode desirable
If two 3560s were used or two 3650s there was no issues and connectivity was as it should be. The problem arose when one 3560 was used and one 3650. Then there was no connectivity. The solution was to put one device in auto negotiate mode by removing "switchport mode trunk" from port-channel 1, gig 0/23 and gig 0/24.
I found the command "show int trunk" the most useful in debugging this problem. It showed if the trunk even existed or not.
If this is a little vague to you, it is intentional sort-of. The setup is in a classified area and it is painful to get data in and out of it. Sorry. I can try to explain better if anyone needs it.
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