cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
1623
Views
0
Helpful
3
Replies

Switch not sending dhcp discover messages to router

ericclapham
Level 1
Level 1

I have 6 Cisco SG200 switches on my network.  The three switches on the east side of the building are up and running fine with DHCP ( I know I know) but the three on the west side are all using the default IP address of 192.168.1.254.  A month ago only two were using the default but the third lost power and had to be rebooted and cannot obtain DHCP.  I am very new to networking so I had some help in doing some packet captures on the router and know that the 3 switches are not sending a discover message to the router.  

A few weeks ago I set up the same model switch in another building and right out of the box with no configuration (with the exception of a 30 second reset hold) the switch got its DHCP and my connected access points are all in direct connect to the internet. I am trying to read up on what settings I need to adjust but I keep telling myself that it shouldn't be this hard.  It should be easy like the other switch setup.  

Is there something very simple I am overlooking (this is my vote since I'm a newbie) or did I somehow just get lucky with the last switch?  Currently the switch is completely default with no gateway.  

I just purchased a CCENT/CCNA book yesterday and I wish I had started teaching myself a few months earlier.  Any help would be greatly appreciated. 

 

I did notice yesterday that the firmware that the switch shipped with back in 2011 is still the present firmware.  Would out of date firmware be a suspect in this mess?

3 Replies 3

Parvesh Paliwal
Level 3
Level 3

Are the switches with default configs ?

Is there a single DHCP server ? Is the DHCP on a router or other dedicated server is implemented ?

Is the scope available for dedicated subnet ?

 

-

Parvesh

I just started with the company a few weeks ago (first IT job) and the network was ran by an individual who was wearing many hats and could not contribute a great amount of time to networking.  All of the switches have default configs.  My first week here we powered up 2 other switches for another building and they came right up with DHCP.

A Meraki MX400 is running everything and is handing out DHCP.  

I just noticed that my subnet mask is a /30.  This network is 5 buildings with 12 switches.  I'm sorry, what do you mean by is the scope available for dedicated subnet?

If your MX400 is handing out DHCP and your getting a /30 I would say you need to find out how it is configured to better understand the network design. If you have 5 buildings and 12 switches I would expect you have some VLAN setup somewhere! Are your switches are connected using trunk links etc etc.

I would certainly recommend getting static IP addresses on your switches outside of any DHCP scope so you know where they are when you need to manage them.