1841 with AIM VPN module question ?

Answered Question
Dec 11th, 2007
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What is the difference between the onboard VPN module and adding an AIM module to an 1841 ?


If I do not install an AIM module I get

Cisco 1841 (revision 7.0) with 235520K/26624K bytes of memory.

Processor board ID FTX1127W1AH

2 FastEthernet interfaces

1 terminal line

1 Virtual Private Network (VPN) Modules


If I install the AIM I get the AIM light lit and the following

Cisco 1841 (revision 7.0) with 235520K/26624K bytes of memory.

Processor board ID FTX1127W1AH

2 FastEthernet interfaces

1 terminal line

2 Virtual Private Network (VPN) Modules


Therefore I am wondering do I even need to add the AIM card to this router or is one built in ?


Thanks


Darren

Correct Answer by Jon Marshall about 9 years 4 months ago

Hi Darren


Its a bit vague but from the Cisco product data sheet on the 1841 router


=============================================


AIM-Based VPN Acceleration

• Support for an optional dedicated VPN AIM can deliver two to three times the performance of embedded encryption capabilities.


=============================================


Full link:


http://www.cisco.com/en/US/products/ps5853/products_data_sheet0900aecd8016a59b.html


So they seem to be suggesting that you can more than double your performance with a separate AIM.


If your internal VPN encryption is enough for your needs then yes you don't need the extra VPN module, because it is still hardware accelerated.


HTH


Jon

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Collin Clark Tue, 12/11/2007 - 13:41
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Darren-


The AIM card is used for encryption/decryption of IPSec traffic. You should see a difference in CPU utilization with and without the card installed with encrypted traffic flowing. If not, make sure you are using IOS that supports the AIM VPN module. I'm still looking for a command that shows utilization of an AIM card. If I find one, I'll post it.


HTH and please rate.

Correct Answer
Jon Marshall Tue, 12/11/2007 - 13:45
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Hi Darren


Its a bit vague but from the Cisco product data sheet on the 1841 router


=============================================


AIM-Based VPN Acceleration

• Support for an optional dedicated VPN AIM can deliver two to three times the performance of embedded encryption capabilities.


=============================================


Full link:


http://www.cisco.com/en/US/products/ps5853/products_data_sheet0900aecd8016a59b.html


So they seem to be suggesting that you can more than double your performance with a separate AIM.


If your internal VPN encryption is enough for your needs then yes you don't need the extra VPN module, because it is still hardware accelerated.


HTH


Jon

Richard Burts Tue, 12/11/2007 - 14:01
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Darren


Jon is pointing in the right direction. The 1841 comes with some built in hardware assist for VPN encryption processing. Using the built in accelerator relieves load on the processor as compared to the CPU load if all the encryption processing were done in software. But the capacity of the built in accelerator is limited. If the processing requirements of your VPN traffic is limited then the built in accelerator would be enough. If the processing requirements of your traffic are greater then the additional accelerator module provides much more processing power than the built in accelerator.


Perhaps an analogy might help: lets think about buying a car that we can use to take a family vacation and that will carry our luggage for the vacation trip. If you have a small family or not much luggage then the trunk built into the car is adequate. But if you have a large family or if you travel with lots of luggage then you might need to purchase the optional luggage carrier to mount on the roof of the car.


HTH


Rick

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