07-05-2017 07:13 AM - edited 03-08-2019 11:12 AM
Hi All,
I am setting up two 2960 cisco switches, set up two vlans (Vlan 1 (default) Vlan 5). i configured gi1/0/1 to be a trunk port for both switches using :
en
conf t
int gi1/0/1
switchport mode trunk
switchport trunk allowed vlan 1-1000
and i have done this on both switches however the trunk port is not working. i used a crossover cable in port 1 on both switches. when i do
show int trunk
i dont get anything returned.
Can you please advice.
Many Thanks
Abdo
Solved! Go to Solution.
07-05-2017 08:36 AM
ok its configured wrong and has gone into err-disabled mode as per the interface status
the reason is you set portfast which is only for access ports , when the switch bpdu came in it went error the port to stop a loop as it thought it was access port , please remove everything but the below and you will need to bounce the port again , shut , then no shut each port , make sure each side just has the below
int g1/0/1
switchport mode trunk
switchport trunk allowed vlan 1-1000
### A quick way to do it is ....(conft)default int g1/01
That will set it back to original no config just for the port rather than having to type no for each line
07-05-2017 07:28 AM
Hi
you don't need a crossover the switches support mdix so a straight through will do fine
are the vlans added at layer 2 on each switch in the ... show vlan and both trunk ports are up/up each side
try the straight through instead see if it makes a diff your config is fine once the vlans are in place at layer 2
07-05-2017 07:38 AM
Thanks for the fast reply, and yes they are both layer 2 vlans, however can you clarifiy what you mean by "both trunk ports are up/up each side"
07-05-2017 07:44 AM
Hi
that the physical interface are showing up/up on each switch , each port that's set as a trunk , try a straight through it will prob come up
show ip int brief
GigabitEthernet1/0/16 unassigned YES unset up up
07-05-2017 07:52 AM
This is the results i get after typing sh ip int br:
GigabitEthernet1/0/1 unassigned YES unset administratively down down
07-05-2017 07:54 AM
ok that the issue port is manually down , needs to be brought up , make sure both sides are up/up then , run same command again after the no shut on each interface , then show int trunk
(conf t)
int g1/0/1
no shut
07-05-2017 08:00 AM
Ive run the above commands and now when i do:
sh ip int br
im getting:
GigabitEthernet1/0/1 unassigned YES unset down down
07-05-2017 08:04 AM
so when its down /down and not up/down , that means you have a physical layer 1 issue which is either port is shut , the cable is faulty or its not connected at other end , unlikely the port is faulty
make sure both sides are not admin like that last output , the far end where g1/0/1 other end of the trunk is not admin down either
change the cable to straight through standard cat5 /6 cable
You wont see ay trunk info until the ports are up/up each side at interface
07-05-2017 08:11 AM
i dont think it is a port issue because when i run
conf t
int gi1/0/1
switchport mode access
switchport access vlan 5
ex
it works. However when i change it to a trunk port i does not work.
07-05-2017 08:14 AM
physical switch port does not care when its access or set as trunk , it should come up physically either way once the cable is connected between the 2 switches
from both switches where the cable is connected between the ports and its set as trunk
can you post please the
sh run int x/x
and show int x/x
This will allow us to see if there something else causing it
07-05-2017 08:30 AM
07-05-2017 08:36 AM
Hi
A switchport cannot be as trunk or access mode at the same time (it will not affect the port status), but as Mark mentioned you should replace the cable.
07-05-2017 08:36 AM
ok its configured wrong and has gone into err-disabled mode as per the interface status
the reason is you set portfast which is only for access ports , when the switch bpdu came in it went error the port to stop a loop as it thought it was access port , please remove everything but the below and you will need to bounce the port again , shut , then no shut each port , make sure each side just has the below
int g1/0/1
switchport mode trunk
switchport trunk allowed vlan 1-1000
### A quick way to do it is ....(conft)default int g1/01
That will set it back to original no config just for the port rather than having to type no for each line
07-05-2017 08:48 AM
Thank you very much, that has solved my issue.
07-05-2017 08:49 AM
great , glad we could help
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