Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

SG300-28P - Recycling?

Hi there.

First of all apologies if this makes no sense at all. I'm not sure I understand it myself to be honest.

About 3 years ago we moved premises to a larger warehouse. As part of the move we invested in new Cisco routers and a meshed wifi network.

I set all the Cisco routers up and a 3rd Party Contractor did the meshed wifi network.

When he was setting it all up he mentioned something along the lines of "Be careful with Cisco routers, they can cycle your IP pool".

At first I just nodded and smiled as I figured it had nothing to do with us. We use DHCP on the server so I figured it didn't relate to us. DHCP isn't configured for the switches at all.

However, over the past 3 years we occasionally get the odd network freeze. It's like everything stops for about 30 to 60 seconds and then comes back again. Normally it's not a problem but during busy periods (like Christmas and Bank Holidays), we have a lot of network traffic and that's when it's noticeable.

I haven't really thought much of it until I visited a clients site to install a new till system. They mentioned they'd just upgraded all their switches from 3Com to Cisco and during a very busy period on Friday, the exact same thing was happening to the network. The machines that had DHCP assigned addresses would suddenly have a network "freeze" of about 30 to 60 seconds and then it would go back to normal.

We have an external IT company that now look after our network as my duties have moved on in the company, but when I mentioned it to them the MD of that company said "That's funny. We had another client saying they had heard the same thing".

Is there an issue with Cisco switches and IP addresses that are assigned through DHCP from a server rather than through the switches, and if so, is there a way to get them all to live happily together?

Hope any of this makes sense.



Hello northgame,I can't say

Hello northgame,

I can't say that I have heard of this issue so a few things I would do is setup a syslog and enable all logs on the switch.  Then for a kind of getting a live idea of traffic flow on the network is I would set up pings using -t -l 1500 command and ping all the critical hops and devices (servers, switches, gateway, modem, open dns servers).  The reason for the ping test is to see how where in the network I have packet loss to help isolate where the problem may be at.

Hope this helps,


Michael D.

If this post is helpful please rate or mark as correct.

CreatePlease login to create content