Show interface switching

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show interface switching

  • Process
    • These are the processed switched packets.
    • These packets can be packets arriving locally to router (including the control plane packets, like OSPF hello packets)
    • These packets can be packets for which local router doesn't have a entry in CEF table
  • Fast
    • These are fast switched packets (e.i CEF), e.i packets cef switched by local SUP/RP processor
    • In case of distributed system like 7600, these are packets that arrive locally and handled by SUP
    • These can be packets going to the local null0 bucket (or any static route pointing to local router) (look into #Process Switching vs CEF Switching Example)
      • These packets are fast switched because there is an entry in the CEF table, but these packets die locally and so therefore they are handled by SUP
      • This the reason you will find that this counter increments along with Process counter
  • Auton/SSE
    • These are DCEF switched packets, e.i packets switched by line card's processor (DFC Card)
    • NOTE: This is only valid in a distributed system with DFC card, like 7600
    • When traffic is DCEF switched, only this counter increments and Fast (CEF Switched) counter doesn't increment
! Process - Process Switched
! Fast - CEF Switched
! Auton - DCEF Switched

R1#show int t5/3 switching
TenGigabitEthernet5/3
          Throttle count          0
        Drops         RP          0         SP          0
  SPD Flushes       Fast          0        SSE          0
  SPD Aggress       Fast          0
 SPD Priority     Inputs     742085      Drops          0

     Protocol       Path    Pkts In   Chars In   Pkts Out  Chars Out
           IP    Process        787      88544        837     109983
            Cache misses          0
                    Fast          0          0          0          0
               Auton/SSE      10035    1184130      10035    1184130
         CLNS    Process    2340133 9935309778    2340203 10061734792
            Cache misses          0
                    Fast          0          0          0          0
               Auton/SSE          0          0          0          0
          ARP    Process        627      37620        628      70336
            Cache misses          0
                    Fast          0          0          0          0
               Auton/SSE          0          0          0          0
          CDP    Process     155934   65180412     155933   73756309
            Cache misses          0
                    Fast          0          0          0          0
               Auton/SSE          0          0          0          0
R1#

Process Switching vs CEF Switching Example

! Network: 1.0.0.1-R1-R2-R3-3.0.0.1
! OSPF Running
! $INT_R1_TO_R2: Interface on R1 connected to R2
! $INT_R2_TO_R1: Interface on R2 connected to R1

R1#ping 3.0.0.1 repeat 1000
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

! The above traffic will increment Auton/SSE on R2
! However, you will note that Process packets are incrementing
! very slowly. This is due to OSPF Hello Packets arriving R2
R2#show interface switching $INT_R2_TO_R1
     Protocol       Path    Pkts In   Chars In   Pkts Out  Chars Out
           IP    Process        787      88544        837     109983
            Cache misses          0
                    Fast          0          0          0          0
               Auton/SSE  $INCREASES    1184130      10035    1184130

R2(config)#ip route 2.2.2.2 255.255.255.255 null 0
R1(config)#ip route 2.2.2.2 255.255.255.255 $INT_R1_TO_R2
R1#ping 2.2.2.2
U.U.U.U
! The above traffic increments Fast Switch and Process Switch almost equally
R2#show interface switching $INT_R2_TO_R1
     Protocol       Path    Pkts In   Chars In   Pkts Out  Chars Out
           IP    Process   $INCREASES   88544        837     109983
            Cache misses          0
                    Fast    $INCREASES      0          0          0
               Auton/SSE       1111    1184130      10035    1184130

References

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