Comments

  • Hi Ehtu,

    If you look this documentation page, CEF also supports ip load-balacing per-packet. I made some test as well:

    http://www.cisco.com/en/US/products/hw/modules/ps2033/prod_technical_reference09186a00800afeb7.html#wp16220

    Here is my test:

    R1#show run int s0/0
    Building configuration...

    Current configuration : 141 bytes
    !
    interface Serial0/0
     ip address 192.168.0.1 255.255.255.0
     ip access-group 100 in
     ip load-sharing per-packet
     serial restart-delay 0
    end

    R1#show run int s0/1
    Building configuration...

    Current configuration : 141 bytes
    !
    interface Serial0/1
     ip address 192.168.1.1 255.255.255.0
     ip access-group 101 in
     ip load-sharing per-packet
     serial restart-delay 0
    end

    !

    R1#show access-lists
    Extended IP access list 100
        10 permit ip any any (51 matches)
    Extended IP access list 101
        10 permit ip any any (51 matches)
    !

    R2#ping 1.1.1.1 so lo0 re 10

    Type escape sequence to abort.
    Sending 10, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
    Packet sent with a source address of 2.2.2.2
    !!!!!!!!!!
    Success rate is 100 percent (10/10), round-trip min/avg/max = 12/28/88 ms

    !

    R1#show access-lists
    Extended IP access list 100
        10 permit ip any any (69 matches)
    Extended IP access list 101
        10 permit ip any any (69 matches)

    It shows packets are equally forwarded to both interfaces.

    Any comments guys?

    [:D]

  • nnn , your verification is great !  i always used  show ip cef exact route xyz command

  • Hi nnn,

       I agree with you, however, in your eample you use process switching, cause router generated packets use process switching mechanism. You need three routers to show it up with CEF switching (R1---R2---2links----R3) and ping from R1 to R3, show up that R2 can do per-packet load-sharing with CEF switched packets.

    Good luck with your studies!

  • And as rightly said , we should only trust cef labs on real gear !!

  • Hi all

     

    following the link

    http://ieoc.com/forums/p/6135/133708.aspx

    brain said and i quote :

    but i guess cef can do load balancing with ip load-sharing per-packet command ?

    he coulda meant "by default"

    by default >> according to doyle...cef and fastswitching do per destination load balancing for IPV4

    IPV6 CEF supports ONLY per destination load sharing

    LOCALLY generated traffic is ALWAYS process switched....

     

    i HIGHLY doubt people like  BrianMc Gahan are ever wrong about simple stuff like this...i honestly think he didn't complete his thought...

     

     

  • And as rightly said , we should only trust cef labs on real gear !!

    See my this example again:

    Topology: R1 - two links- R2 - R3

     

    R2(config-if)#do show run int fa0/0

    Building configuration...

     

    Current configuration : 149 bytes

    !

    interface FastEthernet0/0

     ip address 192.168.0.2 255.255.255.0

     ip access-group 100 out

     ip load-sharing per-packet

     duplex auto

     speed auto

    end

    !


    R2(config-if)#do show run int fa1/0

    Building configuration...


    Current configuration : 149 bytes

    !

    interface FastEthernet1/0

     ip address 192.168.1.2 255.255.255.0

     ip access-group 101 out

     ip load-sharing per-packet

     duplex auto

     speed auto

    end

    !


    R2(config-if)#do show access-list

    Extended IP access list 100

        10 permit ip any any (118 matches)

    Extended IP access list 101

        10 permit ip any any (195 matches)

    R2(config-if)#do show access-list

    Extended IP access list 100

        10 permit ip any any (126 matches)

    Extended IP access list 101

        10 permit ip any any (203 matches)

    R2(config-if)#do show access-list

    Extended IP access list 100

        10 permit ip any any (138 matches)

    Extended IP access list 101

        10 permit ip any any (215 matches)

    !


    R2#show ip cef exact-route 3.3.3.3 1.1.1.1

    3.3.3.3         -> 1.1.1.1        : FastEthernet0/0 (next hop 192.168.0.1)

    R2#show ip cef exact-route 3.3.3.3 1.1.1.1

    3.3.3.3         -> 1.1.1.1        : FastEthernet1/0 (next hop 192.168.1.1)

    R2#show ip cef exact-route 3.3.3.3 1.1.1.1

    3.3.3.3         -> 1.1.1.1        : FastEthernet0/0 (next hop 192.168.0.1)

    R2#show ip cef exact-route 3.3.3.3 1.1.1.1

    3.3.3.3         -> 1.1.1.1        : FastEthernet1/0 (next hop 192.168.1.1)

    R2#show ip cef exact-route 3.3.3.3 1.1.1.1

    3.3.3.3         -> 1.1.1.1        : FastEthernet0/0 (next hop 192.168.0.1)

    R2#show ip cef exact-route 3.3.3.3 1.1.1.1

    3.3.3.3         -> 1.1.1.1        : FastEthernet1/0 (next hop 192.168.1.1)

    R2#show ip cef exact-route 3.3.3.3 1.1.1.1

    3.3.3.3         -> 1.1.1.1        : FastEthernet0/0 (next hop 192.168.0.1)

    R2#show ip cef exact-route 3.3.3.3 1.1.1.1

    3.3.3.3         -> 1.1.1.1        : FastEthernet1/0 (next hop 192.168.1.1)

    R2#show ip cef exact-route 3.3.3.3 1.1.1.1

    3.3.3.3         -> 1.1.1.1        : FastEthernet0/0 (next hop 192.168.0.1)

    !


    R3#telnet 1.1.1.1 /so lo0

    Trying 1.1.1.1 ... Open



    User Access Verification


    Password:

    !


    R2(config-if)#do show access-list

    Extended IP access list 100

        10 permit ip any any (145 matches)

    Extended IP access list 101

        10 permit ip any any (222 matches)



    In this my test R2 equally distributing IP packets over two links, you can count packets on ACL output. I think CEF does support per-packet load sharing.




    Any queries guys?



    HAPPY STUDY

    [:D]

     

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