Communicating between 2 VLANs

Discussion in 'Cisco' started by Norman Zhang, Aug 7, 2004.

  1. Norman Zhang

    Norman Zhang Guest

    Hi,

    I've a C3550 switch that is segmented into 2 VLANs. I liked to able to
    route packets between 2 VLANs. Default gateway on C3550 is 192.168.11.1
    and IP routing is enabled. However I can't seem to be able to ping from
    192.168.99.1 to 192.168.11.5. Could someone please give me a few pointers.

    Regards,
    Norman

    internet
    |
    *---* *---*
    | | | | 192.168.11.5/26
    *---* *---* gw: 192.168.11.1
    | 192.168.11.1/26 |
    |--------------------*
    | 192.168.11.4/26 (VLAN2)
    *---*
    | | gw: 192.168.11.1
    *---*
    | 192.168.99.1/24 (VLAN1)
    |
    |
    *---* 192.168.99.2/24
    | | gw: 192.168.99.1
    *---*
    Norman Zhang, Aug 7, 2004
    #1
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  2. are you using a router connected to the switch? the router is used to route
    packets between vlans


    "Norman Zhang" <> wrote in message
    news:H0%Qc.63754$T_6.29723@edtnps89...
    > Hi,
    >
    > I've a C3550 switch that is segmented into 2 VLANs. I liked to able to
    > route packets between 2 VLANs. Default gateway on C3550 is 192.168.11.1
    > and IP routing is enabled. However I can't seem to be able to ping from
    > 192.168.99.1 to 192.168.11.5. Could someone please give me a few pointers.
    >
    > Regards,
    > Norman
    >
    > internet
    > |
    > *---* *---*
    > | | | | 192.168.11.5/26
    > *---* *---* gw: 192.168.11.1
    > | 192.168.11.1/26 |
    > |--------------------*
    > | 192.168.11.4/26 (VLAN2)
    > *---*
    > | | gw: 192.168.11.1
    > *---*
    > | 192.168.99.1/24 (VLAN1)
    > |
    > |
    > *---* 192.168.99.2/24
    > | | gw: 192.168.99.1
    > *---*
    slipstream_242, Aug 7, 2004
    #2
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  3. Norman Zhang

    none Guest

    VLANs divide a network as if you had two or more switches.

    *---* *---*
    | | | |
    *---* *---*
    VLAN1 VLAN2

    You need a router if you want traffic to pass between the VLANs.

    Some high end switches have router modules in them or as an option that can
    be used to route between the VLANS using one box.


    "Norman Zhang" <> wrote in message
    news:H0%Qc.63754$T_6.29723@edtnps89...
    > Hi,
    >
    > I've a C3550 switch that is segmented into 2 VLANs. I liked to able to
    > route packets between 2 VLANs. Default gateway on C3550 is 192.168.11.1
    > and IP routing is enabled. However I can't seem to be able to ping from
    > 192.168.99.1 to 192.168.11.5. Could someone please give me a few pointers.
    >
    > Regards,
    > Norman
    >
    > internet
    > |
    > *---* *---*
    > | | | | 192.168.11.5/26
    > *---* *---* gw: 192.168.11.1
    > | 192.168.11.1/26 |
    > |--------------------*
    > | 192.168.11.4/26 (VLAN2)
    > *---*
    > | | gw: 192.168.11.1
    > *---*
    > | 192.168.99.1/24 (VLAN1)
    > |
    > |
    > *---* 192.168.99.2/24
    > | | gw: 192.168.99.1
    > *---*
    none, Aug 7, 2004
    #3
  4. Norman Zhang wrote:

    > I've a C3550 switch that is segmented into 2 VLANs. I liked to able to
    > route packets between 2 VLANs. Default gateway on C3550 is 192.168.11.1
    > and IP routing is enabled. However I can't seem to be able to ping from
    > 192.168.99.1 to 192.168.11.5. Could someone please give me a few pointers.


    Cisco provieds excessive and excellent dosumentation for their hardware
    on their web site.

    Why don't you go there and read that ? There is a really long chapter
    "Configuring IP unicast Routing" for your switch, in the Catalyst 3550
    Switch Software Configuration Guide, which has drawings, examples,
    step-by-step instructions etc. (That same guide is also on the CD
    you got with the switch)

    Go read that. Build a configuration. Then come back and tell what
    did not work. Tell what you did.

    A newsgroup is not a replacement for documentation.

    Regards

    Christoph Weber-Fahr
    Christoph Weber-Fahr, Aug 7, 2004
    #4
  5. Norman Zhang

    JR Guest

    Pray tell, what is a newsgroup for?



    "Christoph Weber-Fahr" <> wrote in message
    news:cf2mdq$v80$06$-online.com...
    > Norman Zhang wrote:
    >
    > > I've a C3550 switch that is segmented into 2 VLANs. I liked to able to
    > > route packets between 2 VLANs. Default gateway on C3550 is 192.168.11.1
    > > and IP routing is enabled. However I can't seem to be able to ping from
    > > 192.168.99.1 to 192.168.11.5. Could someone please give me a few

    pointers.
    >
    > Cisco provieds excessive and excellent dosumentation for their hardware
    > on their web site.
    >
    > Why don't you go there and read that ? There is a really long chapter
    > "Configuring IP unicast Routing" for your switch, in the Catalyst 3550
    > Switch Software Configuration Guide, which has drawings, examples,
    > step-by-step instructions etc. (That same guide is also on the CD
    > you got with the switch)
    >
    > Go read that. Build a configuration. Then come back and tell what
    > did not work. Tell what you did.
    >
    > A newsgroup is not a replacement for documentation.
    >
    > Regards
    >
    > Christoph Weber-Fahr
    >
    >
    JR, Aug 8, 2004
    #5
  6. Norman Zhang

    PES Guest

    "JR" <> wrote in message
    news:NgfRc.316079$%...
    > Pray tell, what is a newsgroup for?
    >


    To help people help themselves.
    PES, Aug 8, 2004
    #6
  7. Norman Zhang

    Scooby Guest

    The 3550 is a layer 3 switch, which means it does route - all you need is to
    make sure ip routing is turned on, and you apparently have. I suspect that
    your traffic is getting to the destination, but the return traffic is not
    making it to you. Which would mean that you don't have the correct route on
    the 192.168.11.1 back to 192.168.99.1. Or, perhaps, there is an access-list
    getting in the way. But, I'd try a tracert both ways as a first step. A
    sniffer at different points in the network would help too.

    Hope that helps,

    Jim


    "slipstream_242" <> wrote in message
    news:yT3Rc.312$...
    > are you using a router connected to the switch? the router is used to

    route
    > packets between vlans
    >
    >
    > "Norman Zhang" <> wrote in message
    > news:H0%Qc.63754$T_6.29723@edtnps89...
    > > Hi,
    > >
    > > I've a C3550 switch that is segmented into 2 VLANs. I liked to able to
    > > route packets between 2 VLANs. Default gateway on C3550 is 192.168.11.1
    > > and IP routing is enabled. However I can't seem to be able to ping from
    > > 192.168.99.1 to 192.168.11.5. Could someone please give me a few

    pointers.
    > >
    > > Regards,
    > > Norman
    > >
    > > internet
    > > |
    > > *---* *---*
    > > | | | | 192.168.11.5/26
    > > *---* *---* gw: 192.168.11.1
    > > | 192.168.11.1/26 |
    > > |--------------------*
    > > | 192.168.11.4/26 (VLAN2)
    > > *---*
    > > | | gw: 192.168.11.1
    > > *---*
    > > | 192.168.99.1/24 (VLAN1)
    > > |
    > > |
    > > *---* 192.168.99.2/24
    > > | | gw: 192.168.99.1
    > > *---*

    >
    >
    Scooby, Aug 8, 2004
    #7
  8. Norman Zhang <> wrote in
    news:H0%Qc.63754$T_6.29723@edtnps89:

    > Hi,
    >
    > I've a C3550 switch that is segmented into 2 VLANs. I liked to able to
    > route packets between 2 VLANs. Default gateway on C3550 is
    > 192.168.11.1 and IP routing is enabled. However I can't seem to be
    > able to ping from 192.168.99.1 to 192.168.11.5. Could someone please
    > give me a few pointers.
    >
    > Regards,
    > Norman
    >


    Hi Norman

    What does "Show int desc" tell you... Are the VLANs up'n'runnin?
    Are the VLANs in your VLAN database (show vlan database)?

    Cheers Lars
    Lars Christensen, Aug 8, 2004
    #8
  9. Norman Zhang

    Norman Zhang Guest

    > The 3550 is a layer 3 switch, which means it does route - all you need is to
    > make sure ip routing is turned on, and you apparently have. I suspect that
    > your traffic is getting to the destination, but the return traffic is not
    > making it to you. Which would mean that you don't have the correct route on
    > the 192.168.11.1 back to 192.168.99.1. Or, perhaps, there is an access-list
    > getting in the way. But, I'd try a tracert both ways as a first step. A
    > sniffer at different points in the network would help too.


    Thanks Jim. You are correct, echo reply is dropped by 192.168.11.1. I
    have fixed the problem by adding a static route to 192.168.11.5.

    Regards,
    Norman
    Norman Zhang, Aug 11, 2004
    #9
  10. Norman Zhang <> wrote in message news:<xziSc.1284$fz2.162@edtnps89>...
    > > The 3550 is a layer 3 switch, which means it does route - all you need is to
    > > make sure ip routing is turned on, and you apparently have. I suspect that
    > > your traffic is getting to the destination, but the return traffic is not
    > > making it to you. Which would mean that you don't have the correct route on
    > > the 192.168.11.1 back to 192.168.99.1. Or, perhaps, there is an access-list
    > > getting in the way. But, I'd try a tracert both ways as a first step. A
    > > sniffer at different points in the network would help too.

    >
    > Thanks Jim. You are correct, echo reply is dropped by 192.168.11.1. I
    > have fixed the problem by adding a static route to 192.168.11.5.
    >
    > Regards,
    > Norman


    Norman,

    Sorry to state the obvious (and tell me to sod off if I am insulting
    your intelligence), but the devices on the two VLANs will have
    different default gateways and it was just that you only made mention
    of the one def g/w 192.168.11.1 in your original question.

    The devices on 192.168.11.0 network will have the 192.168.11.1 router
    as the def g/w and devices on the 192.168.99.0 network will have
    192.168.99.1 as the def g/w. I hope I have got the router addresses
    right - I was having trouble deciphering your diagram as is not
    formatted properly on the view I have of it.

    What was the exact static route that you added? I was also having
    trouble working out how that route solved the problem.

    Pete
    Pete Mainwaring, Aug 11, 2004
    #10
  11. Norman Zhang

    Norman Zhang Guest

    Hi Pete,

    > The devices on 192.168.11.0 network will have the 192.168.11.1 router
    > as the def g/w and devices on the 192.168.99.0 network will have
    > 192.168.99.1 as the def g/w. I hope I have got the router addresses
    > right - I was having trouble deciphering your diagram as is not
    > formatted properly on the view I have of it.


    Sorry. You need use fixed size (courier) fonts to see the diagram correctly.

    > What was the exact static route that you added? I was also having
    > trouble working out how that route solved the problem.


    I added

    route add 192.168.99.0 netmask 255.255.255.0 gw 192.168.11.4

    to host 192.168.11.5.

    Regards,
    Norman
    Norman Zhang, Aug 12, 2004
    #11
  12. Norman Zhang <> wrote in message news:<5uDSc.8259$X12.2386@edtnps84>...
    > Hi Pete,
    >
    > > The devices on 192.168.11.0 network will have the 192.168.11.1 router
    > > as the def g/w and devices on the 192.168.99.0 network will have
    > > 192.168.99.1 as the def g/w. I hope I have got the router addresses
    > > right - I was having trouble deciphering your diagram as is not
    > > formatted properly on the view I have of it.

    >
    > Sorry. You need use fixed size (courier) fonts to see the diagram correctly.
    >
    > > What was the exact static route that you added? I was also having
    > > trouble working out how that route solved the problem.

    >
    > I added
    >
    > route add 192.168.99.0 netmask 255.255.255.0 gw 192.168.11.4
    >
    > to host 192.168.11.5.
    >
    > Regards,
    > Norman


    Sorry Norman,

    Still can't get the diagram in a readable format even with fixed size
    font.

    I assume the default g/w on 192.168.11.5 isn't 192.168.11.4 - is that
    correct?

    Could you post the relevant bits of the c3550 config? Plus ipconfig
    displays for a couple of the devices on each of the two VLANs if
    possible?

    Thanks,

    Pete
    Pete Mainwaring, Aug 12, 2004
    #12
  13. Norman Zhang

    Norman Zhang Guest

    Norman Zhang, Aug 12, 2004
    #13
  14. Pete Mainwaring, Aug 13, 2004
    #14
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