Updating Edge Router - Cisco 3825 (revision 1.2)

[stownsend]

We have a Cisco 3825 Router from Maybe 2010 or Earlier.   Its currently being used to Connect the Corp Office to the internet at 50MB. We are looking to Upgrade to 100MB connection.  The Internet Connection is an Ethernet Handoff. We have two Public Class C Address Spaces.  We Currently use VLANs on the Corp Public Interface that connect to a Layer 3 Switch.  

What would be my Upgrade Path for this unit?  I was looking at the ISR 4331, though was not sure if that was the route to take. 

Here is the Info from the Current Router:

CPU utilization for five seconds: 2%/0%; one minute: 2%; five minutes: 2%

          111111 1 11             1 1111    1        1     1 111 11           

      638901171191810987686464656707110099871786693670548890912181198846397836

  100                                                                         

   90                                                                         

   80                                                                         

   70                                                                         

   60                                                                         

   50                                                                         

   40                                                                         

   30                                                                         

   20        *                                                                

   10 * ******************* * ******************** **** ************** * *** *

     0....5....1....1....2....2....3....3....4....4....5....5....6....6....7..

               0    5    0    5    0    5    0    5    0    5    0    5    0  

                   CPU% per hour (last 72 hours)

                  * = maximum CPU%   # = average CPU%

Cisco 3825 (revision 1.2) with 226304K/35840K bytes of memory.

Cisco IOS Software, 3800 Software (C3825-IPBASEK9-M), Version 15.1(3)T, RELEASE SOFTWARE (fc1)

2 Gigabit Ethernet interfaces

6 Serial interfaces (Not Used)

DRAM configuration is 64 bits wide with parity enabled.

479K bytes of NVRAM.

62720K bytes of ATA System CompactFlash (Read/Write)

[Joseph W. Doherty · Accepted solution]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages wha2tsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Your 3825 isn't working very hard supporting your 50 Mbps, is it?

Is your 100 Mbps total traffic, or 100 Mbps duplex traffic?

If the 100 Mbps is for total bandwidth, the basic 4331 should be fine (as might the 4321 upgraded to 100 Mbps).

If the 100 Mbps is for duplex, a performance upgraded 4331 should be fine.

Since your actual CPU loading, as posted, is so low, even for 100 Mbps duplex, you might consider licensing just basic performance, and later upgrade performance, if needed.

[stownsend]

That usage Graph was for our Current 50MB Connection. I believe it is 50MB Full-Duplex. 

I did start the post without looking at the CPU Graph thinking that it was a 6 +Year old Router that was repurposed for the internet connection.   

I suppose I could also see about updating the ISO to something more current too, I'm sure there are a few Fixes and performance tweaks in newer versions.

Thank you!

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages wha2tsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Cisco documents the 3825 as supporting (fastpath) 350 Kpps (235 Mbps) forwarding of minimum size packets.  Average packets sizes are usually much more than minimum, increasing throughput, but production configs require more CPU cycles, and some packets are process switched (over 10x slower).  Usually, you're okay allowing for about 1/4 of the PPS rating's bandwidth for duplex traffic.  I.e. a 3835 should usually handle about 50 Mbps, which seems to be true in your case.

Again, as your posted CPU utilization appears so low (what's the 36 hour stats?), you might be okay even with your 3825 on a 100 Mbps link.

PS:

Newer IOS versions rarely increase performance, but fixes are important, especially those security related.  Depending on your needs, new IOS version can provide some very useful new features.