Showing results for 
Search instead for 
Did you mean: 

UC560 Freeze on file download HIgh CPU

Level 1
Level 1


Hi all,

i have custormer where i installed UC560, recently ISP upgraded internet connection speed  to cca 100Mbps.

when user downloads files or runs speedtest. UC freezes. even phones becomes inresponsive. configuration have 20 phones.

I am avare that 100Mbps is maby too m uch for UC but why freeze and high cpu utilization and how to prevent it.

I apriciate any sugdestions.




6 Replies 6

Jason Blodgett
Level 1
Level 1

Hi Goran,

I'm having the same exact problem.  Our internet connection isn't quite that fast, somewhere around 50-60 Mbps, but I can't download much of anything without hearing about somebody's phone rebooting and re-registering.

I've been told my Cisco we should consider getting a different router, but we have a couple other small locations with UC540s and we're using the muti-site setup.  We're a smaller company and we don't necessarily want to go through the hassle and expense of putting a router in front of our UC560.  We haven't had them very long, and I have a hard time believing this device can't handle a handful of users.

Were you able to come up with a solution to your issue?

I would really appreciate any info.

Thank you,


Hi, Jason

thanx for your reply. I couldnt find any "normal" solution so I was forced to play with CLI and put rate limit on wan interface. I run number of tests and came to conclusion that 25mbps is maximum for resonable cpu utilization during download (about 80%) and stable work. In the mean time customer bought firewall apliance (witch they planed anyway) so UC now is only workin for phones and SIP trunk.

I sopose that you have that isue only on main site ?

What you have on ISP side (router or switch) and do you have (one ore more) static or dynamic public (wan) address?




Hi Goran,

That's good info to know.  I was told by Cisco support I might need another firewall and set it up with the UC the way you described.  I'm not totally sure what to get.  I want something that's easy to manage.  I'm not a whiz with all this networking stuff, but I typically can figure things out.

I can't say we've had the issue at other locations.  In fact I've tried running speed tests at the other locations, where they have 50 mbps connections, and the UC seems to handle it a lot better.  The CPU spikes pretty good, but it doesn't quite max out at 100%.  It'll hit 95% for a couple seconds then make it's way back down into the 80s.

We currently have a couple static public IP addresses.  I'm not sure what you mean by what I have on ISP side (router or switch).  We have our incoming (fiber) connection plugged into the WAN interface on the UC.  I have two Cisco switches.  Each of them are plugged into the Expansion slots on the UC.

What kind of firewall did your customers go with?  I have been looking different devices and I'm a little overwhelmed by it all.  One options I found I liked was pfsense.  I started tinkering around with it and set it up at my house.  It seems pretty nice.

Any suggestions?




I asked what you have on isp side becouse i wanted to propose solutions that mdube sugjested. that is certenly one way to go. I dont exactly know what brend of firewall my custormer instaled, becouse they bought/leased it from isp and they configured it. I usualy use Cisco ASA55xx for firewall solutions depending on customer needs.

If you dont need advanced firewall. you can go with some cisco small bussines router. but certenly have in mind maximum througput.



Hi Goran,

Sorry for the confusion.  We have a fiber line coming straight into our building and that is what plugs into the UC's WAN port.  I will take a look at the ASA55xx and see what would fit our needs.  Thank you for all your help.  I can now go to my supervisors with a little more information.  What irritates me the most about having this issue is we had this same fast fiber connection when we moved to the UC560.  It was suggested by whoever we were working with at the time and they made no mention of the bandwidth limits being so low.  I guess sometimes you really have to wonder what some of these guys really know.  Anyway, thanks again!

Best Regards,


Level 1
Level 1

Hello guys, just saw this thread.


Yes it is unfortunate but true, that the UC500 don't support very high Internet speeds. You will get roughly 20-30Mbps a best, depending on the load you have, rules, nating, etc.


Here's one thread talking about this 


Your best bet would be to have a router for Internet access. From there, multiple network infrastructure are possible for you.

1- Either they both (UC500 and other router) facing the Internet (need 2 public IPs),

2-UC500 behind router (bit more complicated to setup if you have multisite configurations as you won't be able to use CCA if the other router is not a SA520... which I recommend you stay away btw)

3-UC500 just plugged in the network to manage the phone network, computers linked to the router to have Internet access.