SG 300 hanging when assigning IP to new VLAN on SG 300 Switches

[srikar.prabhala]

I have a new SG 300 Switch. When I try to configure a new vlan and assign an IP GUI/SSH hangs up. But when I turn off dhcp relay on vlan1 and try to create a new vlan and assign ip it's working fine. Any reason behind that? Thank you!!

[Georg Pauwen]

Hello,

odd indeed. I can only imagine that if you create a new Vlan, with DHCP Relay enabled, it tries to autmatically assign an IP address to the new Vlan. Does this also happen with 'DHCP Auto Configuration' turned off (Administration > File Management > DHCP Auto Configuration) ?

[srikar.prabhala]

Thank you for your reply!! It's a brand new switch with only VLAN1 configured and dhcp relay turned on it at interface level. Tried disabling 'DHCP Auto Configuration' and it's still same.

***Not working Scenario***

Default Settings:

interface vlan1 

ip address 192.168.1.254 255.255.255.0

DHCP Relay On->

Trying to add a new VLAN:

interface vlan2

ip address 10.1.1.1 255.255.255.0 (When i press enter at this point device is getting hung)

***Working Scenario******

Default settings:

interface vlan1 

ip address 192.168.1.254 255.255.255.0

DHCP Relay on->

Settings I changed to make it work:

interface vlan1

no ip dhcp relay

do wr

Adding new VLAN:

interface vlan2

ip address 10.1.1.1 255.255.255.0 ( Working fine after pressing enter)

After this tried enabling DHCP relay globally and added another VLAN and assigned IP it's working fine. For some reason it's getting hung only when dhcp relay is turned on at VLAN1 interface level.

Thank you!!

[Georg Pauwen]

Hello,

odd behaviour. Usually, on a full IOS device, you would turn on debugging to find out what is going on, but this switch does not really have any debug commands. Maybe you can hook up a sniffer such as Wireshark and check at the packet level what is happening.

Is this switch running the latest firmware (release 1.4.11.5) ?

[balaji.bandi]

These small business switch, they intentioned to auto enable DHCP for the new VLAN as per the document i see and understand.

So when you disable DHCP it works because there is no relay, good to know for the other users who have same issue may be this is learn lesson for them, when they creating VLAN,

May be this was not the case when you do SSH or Console.

[paul driver]

Hello

So, you’re having problems when creating an additional  l3 vlan on the switch and then ssh'ing to the same switch correct.
Im not sure what dhcp relay has anything to do with it at this time other than does the switch support multiple L3 interfaces or is it just a L2 switch?

Having never had any exposure to these models can you confirm if dhcp relay is enabled globally?
I would say for a more deterministic approach the dhcp relay needs to be manually applied to each specific L3 interface for it to be used successfully if that is its applicable on this switch model.