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Interface Stats: cache misses

richard.raehal
Level 1
Level 1

I have a Cisco 2801 router.  It was configured by someone else and I am currently documenting the system.  I am looking at VLAN's, performance, and othe rmetrics to get a baseline for our network.  I am new to using Cisco routers in a production environment.  All of my major work until recently was in a Cisco based school lab.

One of the complaints I receive from my users is that the remote access is very slow.  When I run the "show interfaces switching" command I get this output for the VPN interface:

FastEthernet0/3/0 Denver SSL

          Throttle count          0

           Drops         RP          0         SP          0

           SPD Flushes       Fast          0        SSE          0

           SPD Aggress       Fast          0

           SPD Priority     Inputs      17292      Drops          0

Protocol  IP

      Switching path    Pkts In   Chars In   Pkts Out  Chars Out

      Process              2710671  463145378    8592539  806405734

      Cache misses     2318572          -          -          -

      Fast                    293912469 2182947899  300944488 3412479371

      Auton/SSE          0          0          0          0

Under cache missing I see 2318572 packets.  The total number of packets in is 2710671.  Does the chache misses number indicate a packet switching problem that can be causing my slow VPN connection?  We are using a Sonicwall SRA 4200 for remote access.  All of the remote access traffic is over port 443 for the SSL VPN.  I am still readin about the different type of switching process versus fast versus SSE versus etc...

I can connect to the VPN server and run spped tests.  The speed tests will show a maximum speed of 3Mbps (Dual T1) if I run the tests when the services are not being utilized so I do not think my issue is spped realted.  I can copy a file form the network and receive a download at 8-10KB per second when the line speed allows 340KB per second.  I am thinking baout htis problem incorrectly?

The issue with slow response started when we installed the Sonicwall VN and reconfigured router 8 months ago.  Our company was sold.  The old remote acces used a Juniper VPN system in another state and it still seems faster than what we have now.

2 Replies 2

Richard Burts
Hall of Fame
Hall of Fame

Richard

If you are reading about process versus fast versus SSE versus etc then you are reading very old documentation

In IOS for quite some time Cisco has adopted CEF switching and it is a very good, v ery efficient replacement for these other switching methods.

I know what cache misses represent in the environment of fast switching but not in the environment of CEF. So my first question to you would be to ask you to verify whether CEF switching is enabled on this router or not.

HTH

Rick

HTH

Rick

I do have CEF switching enabled.  Here are the settings for that interface. 

  IP fast switching is enabled

  IP fast switching on the same interface is disabled

  IP Flow switching is enabled

  IP CEF switching is enabled

  IP CEF Flow Fast switching turbo vector

  IP multicast fast switching is enabled

  IP multicast distributed fast switching is disabled

  IP route-cache flags are Fast, Flow cache, CEF, Subint Flow

This is the document I was reading to help my understanding regarding how the switching works:

http://www.cisco.com/en/US/docs/ios/12_3/switch/command/reference/swi_s1.html

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