About marking and CEF

From: sabrina pittarel (sabri_esame@yahoo.com)
Date: Tue Aug 29 2006 - 02:30:32 ART


Hi,
 do I need to enable CEF when marking traffic?
 From Cisco documentation it seems it is required:
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Prerequisites for Marking Network Traffic
 
 b"In order to mark network traffic, Cisco Express Forwarding (CEF) must be configured on both the interface receiving the traffic and the interface sending the traffic.
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 but I can see it working even without CEF.
 
 Topology:
 
                       e0/1 e0/2 e0/0
 R1 --------------------- R3 -----------------------R2
 
 
 I'm pinging from R1 to R2. R3 e0/1 has a policy-map in ingress direction that marks all ingress traffic as af43.
 On R2 I have an access list that permits and logs traffic with DSCP af43.
 
 On R3:
 ---------
 
 R3#sh run int e0/1
 Building configuration...
 
 Current configuration : 125 bytes
 !
 interface Ethernet0/1
  description "to R1 e0/0"
  ip address 136.1.17.7 255.255.255.0
  service-policy input e0/1-in-pm <<<<<<<<<<<<<<<<<<<
 end
 
 R3#sh ser
 R3#sh policy-map e0/1-in-pm
   Policy Map e0/1-in-pm
     Class class-default
       set dscp af43 <<<<<<<<<<<<<<<<<<<<<<<<
 R3#sh policy-map int e0/1
  Ethernet0/1
 
   Service-policy input: e0/1-in-pm
 
     Class-map: class-default (match-any)
       5 packets, 570 bytes
       5 minute offered rate 0 bps, drop rate 0 bps
       Match: any
       QoS Set
         dscp af43
           Packets marked 5 <<<<<<<<<<<<<<<<
 R3#
 R3#sh ip cef
 %CEF not running
 Prefix Next Hop Interface
 
 
 
 On R2:
 
 R2#
 *Aug 29 05:26:05.931: %SEC-6-IPACCESSLOGDP: list 100 permitted icmp 136.1.17.1 -> 136.1.27.2 (0/0), 4 packets
 R2#
 R2#
 R2#sh run int e0/0
 Building configuration...
 
 Current configuration : 117 bytes
 !
 interface Ethernet0/0
  description "to SW1 e0/2"
  ip address 136.1.27.2 255.255.255.0
  ip access-group 100 in
 end
 
 R2#sh ip access
 R2#sh ip access-lists 100
 Extended IP access list 100
     10 permit ip any any dscp af43 log (5 matches)
 R2#
 
 Sabrina



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