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New Member

Extremely poor internet performance 1841


To add more to this,  somehow I missed it but I had quite a few CRC errors on the outside interface.  I switched the FastEthernet0/0 to speed auto, duplex auto and now I am getting about 45Mbps download speed.  I would still like to see the router get closer to 60 though,  is there anything I could tweak in the config that might increase the speed of this just a little bit?  Or is an 1841 only rated to about 45Mbps with all the firewall features turned on?

**End Edit**


A school I am doing some volunteer work for has a 60/4 coax internet service through Charter communication.  I just put in an older Cisco 1841 router and used my default standard config I use at many other sites.  For some reason I am only getting about 6 - 8 mbps download speeds with the router.  When I plug directly into the cable modem with my laptop I am getting the advertised speeds.

Attached is my config, it looks pretty standard to me and for the life of me I can not see why this router would be performing so poorly.  The CPU utilization is very low,  I have to be missing something though.

Thank you everyone


 Hi , Remove inspect rule and


Hi ,

 Remove inspect rule and check ,  

 ip inspect fw_inspect out

else apply inspect rule on LAN interface towards in direction .




New Member

I have tried this and I have

I have tried this and I have not seen any noticeable speed improvements.  Still sitting around roughly 7mbps speed.  I just can not believe the 1841 is so old that it can not handle the connection speeds.

Hi ,Router 1841 , should

Hi ,

Router 1841 , should supports upto 75,000 PPS

ISR 1841 75,000 38.40 No 

Check for Speed & duplex settings on your modem , Whether it negotiating with 100 Mbps speed & full  duplex  .




New Member

I'm having the same issue

I'm having the same issue with the 1841 I get about 12Megbit were I can get over 20 connected with a cheap old linksys router. If you look at the processor it's pegged at 100% after doing some research I found the 1841 has a slow CPU it's max is only 38meg that's not even natting. I assume when you nat the CPU is maxed out.  My IP input shows 70% while downloading a 500meg file. I'm going to try an ASA5200  


120   184159140    71050305       2591 66.79% 24.54%  6.34%   0 IP Input

  100 ********     ***********************************
   90 ********     ***********************************
   80 ********     ***********************************     *****
   70 ********     ***********************************************
   60 ************************************************************
   50 ************************************************************
   40 ************************************************************
   30 ************************************************************
   20 ************************************************************
   10 ************************************************************
               0    5    0    5    0    5    0    5    0    5    0
               CPU% per second (last 60 seconds)


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