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Bronze

Performance on Cisco 3945 running IOS 15.3(3)

I have a very simple scenario with Cisco 3945 running IOS c3900-universalk9-mz.SPA.153-3.M.bin with two interfaces g0/0 (external) and g0/1 (internal).

I setup NAT on the router as follows:

ip cef

interface g0/0

  ip address 1.1.1.1 255.255.255.252

  ip nat outside

interface g0/1

  ip address 192.168.1.254 255.255.255.0

  ip nat inside

ip access-list extended nat

  permit ip 192.168.190.0 0.0.0.255 any

ip nat inside source list nat interface g0/0 overload

then I have a linux host with ip address 192.168.1.254 behind g0/1 with the gateway of the router 192.168.1.254.  I am able to push 950Mbps through the router without any issues.  So far so good.

No I decide to create an ACL and apply this ACL on interfage g0/0:

ip access-list extended External

  permit ip any any log

interface g0/0

  ip access-group External in

When I apply the ACL on the External interface, the throughput on the router goes from 950Mbps down to 160Mbps, an 80% drop in performance.  Why?

Anyone knows how to improve this?

Thanks,

4 REPLIES
Cisco Employee

Performance on Cisco 3945 running IOS 15.3(3)

Hi,

Is the log keyword. Log will force the packet being process switched, so performance will drop.

HTH,

Lei Tian

Bronze

Performance on Cisco 3945 running IOS 15.3(3)

Thanks.  That does work.  However, that does not explain the fact that I am not seeing performance issues on the ASR 1002 and I have about 2000 lines of ACL on the ASR external interface.

Super Bronze

Re: Performance on Cisco 3945 running IOS 15.3(3)

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Posting

The ASR is a different architecture, it has hardware forwarding.  (Note: the ASR 1K series, seems to be somewhat like the earlier 7300 series with NSE-100 or -150 or the 7200 series with NSE-1.)

Additionally, the prior 7200s, but not ISRs, had a "compiled ACL" feature that would improve performance for lengthy ACLs - don't know if the ASR 1K has that too.

Non-technically, 3945 vs. ASR 1002 is comparing apples to oranges. 

Cisco Employee

Re: Performance on Cisco 3945 running IOS 15.3(3)

Hi,

ASR is different platform. It uses hardware offload most if the features, just like 6500, 7600. If still not convinced, hope the following document help.
http://www.cisco.com/web/about/security/intelligence/acl-logging.html

HTH,
Lei Tian

Sent from Cisco Technical Support iPhone App

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