CCIE Pursuit Blog

May 15, 2008

Lab Tip: Remembering IP Precedence Values

I’ve never bothered to memorize the Cisco descriptions of IP Precedence values (i.e. IP Precedence 4 is “flash-override”).  I’ve hit a couple of labs which ask you to manipulate traffic based on these descriptions.  For instance:

“Drop all flash traffic coming into r1 from VLAN 6.”

Some commands such as ‘random detect precedence’ only use the 0 – 7 values: 

r1(config-if)#random-detect precedence ?
  <0-7>  IP precedence
  rsvp   rsvp traffic

You could look this up in the DOC CD, but there’s a quick and dirty way to do this on the command line.

1) Create a class-map.
2) Type ‘match ip precedence ?’ to see the context-sensitive help.  This will give you a list of the IP Precedence values along with their descriptions.
3) Get what you need and remember to delete the class-map.

Rack13R6(config)#class-map FAKE
Rack13R6(config-cmap)#match ip precedence ?
  <0-7>           Enter up to 4 precedence values separated by white-spaces
  critical        Match packets with critical precedence (5)
  flash           Match packets with flash precedence (3)
  flash-override  Match packets with flash override precedence (4)
  immediate       Match packets with immediate precedence (2)
  internet        Match packets with internetwork control precedence (6)
  network         Match packets with network control precedence (7)
  priority        Match packets with priority precedence (1)
  routine         Match packets with routine precedence (0)

Rack13R6(config-cmap)#exit
Rack13R6(config)#no class-map FAKE

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6 Comments »

  1. Buddy, this is the kind of info that can save us many time during the lab!

    Thanks for this one also!

    Comment by Caue Wailemann — May 15, 2008 @ 9:26 am | Reply

  2. […] Lab Tip: Remembering IP Precedence Values « CCIE Pursuit like this – nice and easy way of getting at information that’s just not worth cramming… […]

    Pingback by Doug’s Ramblings » Blog Archive » links for 2008-05-15 — May 15, 2008 @ 5:47 pm | Reply

  3. […] Lab Tip: Remembering IP Precedence Values Posted by cciepursuit Filed in Cisco, Cisco Certification, IOS, Lab Tips, QoS Tags: CCIE, CCIE Lab, Certification, Cisco, Cisco Certification, DSCP, IP Precedence, QoS […]

    Pingback by Lab Tip: Finding Default WRED Values « CCIE Pursuit Blog — August 20, 2008 @ 10:22 am | Reply

  4. Life saver! haha just ran across this in the IEWB lab 2 (routine traffic) Thank you sir!

    Comment by CCIETalk.com — August 31, 2008 @ 12:15 pm | Reply

  5. Another way to do this :

    CAT1(config)#access-list 199 permit ip any any precedence ?
    Precedence value
    critical Match packets with critical precedence (5)
    flash Match packets with flash precedence (3)
    flash-override Match packets with flash override precedence (4)
    immediate Match packets with immediate precedence (2)
    internet Match packets with internetwork control precedence (6)
    network Match packets with network control precedence (7)
    priority Match packets with priority precedence (1)
    routine Match packets with routine precedence (0)

    Cheers~

    Comment by Gary — October 17, 2008 @ 1:18 am | Reply

  6. Or, even without creating a class map and having to delete it afterwards:

    Pretend you are writing an access-list:

    SW2(config)#access-list 101 permit ip any any precedence ?
    Precedence value
    critical Match packets with critical precedence (5)
    flash Match packets with flash precedence (3)
    flash-override Match packets with flash override precedence (4)
    immediate Match packets with immediate precedence (2)
    internet Match packets with internetwork control precedence (6)
    network Match packets with network control precedence (7)
    priority Match packets with priority precedence (1)
    routine Match packets with routine precedence (0)

    And here you have your values!

    Comment by Vladimir — April 16, 2009 @ 3:06 pm | Reply


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