Issue trunking vlan's from one sg200 switch to another.

kassant7
kassant7 used Ask the Experts™
on
I am still learning vlans. I have the concept down and was overjoyed when I thought I understood it enough to use it.

Using a single switch I can create 2 vlans (10&200), separate the traffic and everything is good. When I try to "trunk" those vlan's to another switch things break down. These are cisco Sg200 switches.

On switch 2 (SW2) we have port 2 going to a unifi access point. Switch 2 port 1 goes to switch 1 port 4. Switch 1 port 1 goes to router that provides dhcp & routing for the vlans. It looks like this;

[ap] eth1----eth2 [SW2] eth1-----eth4 [SW1] eth1---eth2 [router] eth1----[modem]

I think the issue may be tagging, but when it doesnt work using wireshark doesnt help.

The vlans exist on both switches. On SW2 ports 1&2 are trunk ports tagged 10&200. On SW1 ports 8 & 4 &1 are trunk ports tagged 10&200. If I move the AP to SW1 eth8, things works like they should. SSID 2 &3 use vlan 10&200 respectively. When i move the AP to SW2 eth2 it doesn't work.

I thought trunk ports carried the vlans from switch to switch. I thought the interfaces had to be tagged so the next switch would know what vlan to put them in. Apparently i have something wrong since it doesn't work properly.

Where have i gone wrong?
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Distinguished Expert 2018

Commented:
What is your setting for trunk mode?
Maybe both sides are in dynamic auto.

switchport mode dynamic auto
– This command makes the interface willing to convert the link to a trunk link if the neighboring interface is set to trunk or desirable mode. Otherwise, the link will become a non-trunking link.

more about trunking:
https://learningnetwork.cisco.com/servlet/JiveServlet/previewBody/14792-102-1-57313/Dynamic%20Trunking%20Protocol.PDF

Can you paste configuration of switches here?

Author

Commented:
How do I get configuration of switch to paste?

Looks like by default, all the ports are in trunk mode. I can switch to general or access, but they all say trunk.
Distinguished Expert 2018

Commented:
Usually you can in terminal window select code and copy with ctrl + C, after copying you can paste code to notepad or any other text editor.
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Author

Commented:
I have never use the terminal window. I use the web interface.

How do i access via terminal window and get the settings for you?
Distinguished Expert 2018

Commented:
Forget about web interface if you are learning Cisco.

1. You need rollover cable (console cable) -connect it to console port
console-cable.gif2. Terminal software (PuTTy, Tera Term, or some other)
3. Set config for terminal sotware:
   9600 baud
 
8 data bits
   
No parity
   
1 stop bit
4. start typing commands

in this case you need just two:
enable (to enter privileged mode)
show running config

then you can copy paste your switch config (both switches)
:)

Author

Commented:
I have one of those cables, but no console port on the switch. Just eth1-8.

Cant we use putty and ssh to the Ip address, or telnet? It's 2014, surely we have more capabilities than a serial connection.
Distinguished Expert 2018

Commented:
Sure we can use telnet or ssh.

But usually when you buy new cisco equipment device don't have ip address so you can't access device on any way except serial link :)

Maybe you have one of those devices with only web interface, but you can give device IP address and allow telnet and set telnet password so you can try login into device.

Author

Commented:
They already have IP addresses. They are static and I can access the web GUIm which is what ive been using to modify the vlans.

What is the next step?
Distinguished Expert 2018

Commented:
enable telnet on switch
get putty set ip address of switch and choose telnet :port 23
and click open

if device have command line enabled - device will ask you for password

Author

Commented:
no telnet/cli on this sg200.
Distinguished Expert 2018

Commented:
OK.
What should be next?

If I can't see configuration...hm...
You said that VLAN 10 and 200 are allowed on trunk.
ADD native VLAN to trunk. DOT1Q trunking can have problem on some switches if native VLAN is not allowed.

Author

Commented:
I can take screen shots!

vlan1 is also allowed on the trunk ports. I will take a SC.
Distinguished Expert 2018

Commented:
ok

Author

Commented:
Default settings

Author

Commented:
Default settings with pic
sg200-117-w.jpg
Distinguished Expert 2018

Commented:
That picture means nothing to me.

I can only see that ports are set as Trunk, native VLAN is 1, and that there is ingress filter on trunk.
You have already told me that you set ports as trunk.  And if that is only think to set everything should work OK.
By default between two switches you should use crossover cable, but every modern switch has auto sensing on port so that either should not be a problem.

Lats try to make it simple:
Check are all vlans allowed on trunks (to eliminate problem with filtering VLAN-s)
try to remove ingress filter (same reason as above)

create needed VLAN-s on both switches

Author

Commented:
where do i check are all vlans allowed on trunks?
both vlans are created on both switches

Author

Commented:
On switch 1, the AP is on port 8. I set the port to general and turned ingress filter off. I didn't see where you could turn the filter off any other way.

The vlan on the AP works. I didnt have to tag the interface or do anything else except turn the ingress filter off.

On switch 2, the AP is on port 2. I turned the ingress filter off for that port as well. SW2 is connected to SW1 on port 4. The vlan on the AP doesnt work.

If i turn the ingress filter off on port4, what issues do we run into with the rest of the traffic coming from SW2?
Commented:
I thought id give an update. We got it working.

On the final switch(es) the ports had to be set as access with ingress filtering off. We also have to change the port vlan to TP instead of UP to make it work properly.

Thanks for everyone's help!

Author

Commented:
Worked well after figuring out port settings.

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