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DHCP not working on SG200-26P


Hi All,

we have 3 SG200-26P.

SW01 Port 26 -> SW02 Port 25

SW02 Port 26 -> SW03 Port 25

The problem only extist on SW03.
We can't get an DHCP adress on the connected device.
Only when I disable the port, save config and reenable the port, save config,
I'll get an IP on that port.
All ports are affected.

There are 2 VLANs, the problem exist on both.


I already searched the forum, without success.


There is no option to connect the switches SW02 and SW03 direct to SW01,
because of the cabeling inside the building.


FW on all switches:

Boot on all switches:


The link is up with 1000Mbit/s right now, I connect a device.


Any ideas?


cheers Martin

6 Replies 6

Georg Pauwen
VIP Master VIP Master
VIP Master



hard to say. What does the port configuration look like ? You could try to configure the 'desktop' macro on the ports, which includes important commands such as 'spanning-tree portfast'...

Hi Georg,
thanks for your reply.
As I think, the port configuration is standard.
Admin Stat UP
SNMP Traps enabled
Auto Negot. Enabled
Auto Adv. Enabled
Preference Mode Slave
Flow Control Disable

VLAN Interface
Interface VLAN Mode General
Admin PVID 1
Frame Type Admit all
Ingress Filter Enable
Administraive VLAN 1UP, 2T
How do I configure the 'desktop' makro, or what do you mean?
The crazy thing is, when I disable an reanable the port, with configuration save ...
the device get an IP address from our DHCP-Server.
I already tried to have the port in only one VLAN, player around with some settings.
In one oft he communities I got the hint to disable CBP ... no success.
Cheers Martin



check page 153 of the attached admin guide for instructions on how to configure an interface with a smartport macro. Use the 'desktop' macro:


Workflow2: To configure an interface as a static Smartport, perform the following steps:

Tyson Joachims
Rising star
Rising star

A few things I would verify:

1. Is SW02 Port 26 & SW03 Port 25 both configured as trunks and allowing both VLANs?

interface gigabitethernet26
 description Link_to_SW03_Port25
 switchport mode trunk
 switchport trunk allowed vlan add 10,20
 no macro auto smartport

2. Does SW03 have both VLANs configured?

vlan database
vlan 10,20

3. Is the interface connected to the computer an access port in the correct VLAN?

interface gigabitethernet8
 spanning-tree portfast
 switchport mode access
 switchport access vlan 10
 no macro auto smartport

I generally stay away from the macro's as they tend to introduce an unstable element for me. You'll notice that in all my interface configurations, I turn off macros.

If you could post the output of a "show run" for SW02 and SW03, that would assist in troubleshooting. Please be sure to remove any usernames and passwords from the configuration before posting.

Hello Tyson,

thanks for your post.
As the SG200-26P has no SSH capability, I can only check that by WebInterface.
- I disabled SmartPort on Port 25 & 26 (smartport.png)

- Both VLANs are available on all switches.

- The ports are configured as trunk (802.1q Trunking) or you talk about port bonding?


You'll find some screenshots attached.


What I really don't understand, when I connect a device to a port, the device will not get an DCHP address.
Only when I disable the port, save config, enable the port, save config the client gets the DHCP configuration.
When I configure the device with a manual IP address, no communication with the network happen.




Rising star
Rising star


Which is the SW03 port your device is connected to? Can you please configure that port as "Trunk 1T,2UP" and check.

Best regards,


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