3640 replacement

tomiczekl · ‎11-07-2008

Hi everybody,

I'm searching for a solution to replace two old 3640 router's that have a too high CPU load (average 60 - 70%)for new services. They both have 15 Subinterfaces, and are connected with a 34mbit ATMcircuit on the main interface (each).

The new router's should have at least the following interfaces:

- 2 FastEthernet/IEEE 802.3 interface(s)

- 1 Serial(sync/async) network interface (s)

- 1 ATM network interface(s)

I have searched the cisco page and spoke to some colleagues, all told me a 38xx or 72xx should have enough ressources but not which model exactly.

Please respond and tell me which model you would take, and why.

Thanks in advance,

best regards

Lukas

CCNA

Giuseppe Larosa · ‎11-07-2008

Hello Lukas,

first of all I would check what processes are using the CPU

try by using

sh proc cpu sorted [1min]

if they are IP input or other traffic related processes what you need is a box with a better CPU.

If you haven't enabled cpu intensive processes like NAT or CBAC a Cisco 3845 could be enough to host two FEs, a module with A/S interfaces and a NM 34 Mpbs and have space for a second ATM NM

But if the ATM E3 link is very used you could think of moving to C7206VXR with NPE-G1/2 in order to have more space to grow and more cpu.

In other threads have been observed with tests that a C3845 cannot use more then two ATM E3 network modules at the same time the third is left not operational by IOS itself.

Hope to help

Giuseppe

tomiczekl · ‎11-07-2008

Thanks Giuseppe & Joseph,

I allready checked the cpu usage and only found traffic and ip related processes in major use.

I will check the show tech again, i think i will find out there wheter it's an E3 or not, but for sure i'll need only one ATM interface. The next larger link would be 155 mbit (~135 in use) and therefor is suppose i would need the 7206VXR model.

let me know if you agree on the need of the 7206vxr in case of an upgrade to an E4 link if possible.

thanks for your help!

best regards

lukas

Giuseppe Larosa · ‎11-07-2008

Hello Lukas,

if you will need to go to STM-1 155 Mbps Cisco 7206VXR should be a better choice

Hope to help

Giuseppe

tomiczekl · ‎11-07-2008

Giuseppe,

do you know if the STM-1 155 Mbps Cisco 7206VXR is compatible to european ATM Services and Frame-relay over ATM?

Joseph W. Doherty · ‎11-07-2008

If you look at the attachment, you'll see a 3640 is rated at 50 to 70 Kpps for Fast/CEF switching. If you look at the other routers, you can scale as you think is necessary. For instance, a 2821 should half your current CPU for the same load, a 2851 by two thirds, etc.

PS:

Normally, 3845, or better, is recommended for full T3 (and your 34 is less), but Cisco's recommendatations are, I believe, very conservative.

tomiczekl · ‎11-07-2008

Thanks Giuseppe & Joseph,

The 2821 are good (in many scenarios), but not the right descision for the scenario i have here (lot of ospf routing, QoS, etc...).

I will check the show tech again, i think i will find out there wheter it's an E3 the 3640 has or not, but for sure I'll need only one ATM interface! The next larger link would be E4 155 mbit (~135 in use) and therefor I suppose i would need the 7206VXR model.

let me know if you agree on the need of the 7206vxr in case of an upgrade to an E4 link if possible.

thanks for your help!

best regards

lukas

Joseph W. Doherty · ‎11-08-2008

Both the 3825 and 3845 support NM-1A-OC3-POM, OC-3/STM-1 but the "SP Services" image is required. Neither could fully drive 155 Mbps (duplex) for 64 bytes packets, although I suspect for "normal" traffic, the 3845 might be able to. If actual traffic demand doesn't push the link to full capacity, either might suffice.

Of course, the 7200/7300 series G1/G2/NSE engines can provide more performance. Unknown whether you need 7206VXR, that depends on number of slots you need. 7204VXR, 7304 and 7201/7301 can provide similar or same performance, since performance depends mostly on installed engine.

Difficult to determine performance needs for things like "(lot of ospf routing, QoS, etc...)" although if you expect OSPF routing to be that demanding, I would suggest re-examination of your OSPF design.

tomiczekl · ‎11-10-2008

thanks joseph!

sorry for my messagedelay.

now i think i know that only a 72xx or higher series will bring the need. Do you only mean with slot's the space for interface controllers (such as gigabit/fastethernet, serial, ATM E3, etc...), or something else?

best regards

lukas

Joseph W. Doherty · ‎11-10-2008

"Do you only mean with slot's the space for interface controllers (such as gigabit/fastethernet, serial, ATM E3, etc...), "

Yes