use cisco 837 as an ethernet router?

Discussion in 'Cisco' started by Arnoud Helmantel, Aug 7, 2005.

  1. Hello there,

    At the moment (and the near future) I can keep using my 837 as my ADSL
    router, but in the more distant future (a few months from now) it is
    likely that my ISP will offer ADSL2/+ connections, which will render my
    837 more or less useless.
    Is it possible to use the LAN ports of my router as an ethernet router
    and use another modem in bridge mode to connect to the Internet?

    For example, can I use FastEthernet1 as a WAN port and the others as LAN
    ports?

    thanks,

    Arnoud


    --
    Please use my first and last name in the address & remove '.invalid'
    Mijn voor- en achternaam gebruiken in het adres zonder '.invalid'
    Arnoud Helmantel, Aug 7, 2005
    #1
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  2. In article <1h0xphq.15t79c1848q9wN%>,
    Arnoud Helmantel <> wrote:
    :Is it possible to use the LAN ports of my router as an ethernet router
    :and use another modem in bridge mode to connect to the Internet?

    As of a year or two ago, Cisco started supporting "DMZ" on the 83x,
    in which one of the 4 LAN ports could be severed from the switch
    group into a different subnet.

    I have no information as to whether the second LAN so formed is
    equvilent to the others or is somewhat restricted.
    --
    "I want to make sure [a user] can't get through ... an online
    experience without hitting a Microsoft ad"
    -- Steve Ballmer [Microsoft Chief Executive]
    Walter Roberson, Aug 7, 2005
    #2
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  3. Hi,

    in my eyes this is a rather bad idea.
    The internals of the Cisco 83x-Routers are as follows:


    +-----------+ +--------------------+
    ----| 5 Port | | Router with |---- DSL etc...
    ----| Switch |-----| 10mbps Ethernet, |
    ----| 100mbps | | ADSL etc... |
    ----| | | |
    +-----------+ +--------------------+
    4x FE

    The "router" itself has only one 10mbps ethernet-interface.
    Behind the router, but on the same circuit-board is a 5-port switch.
    Four of the switchports are connected to the RJ45-ports on the back of
    the router, however the fifth port is soldered to the "router" 10mbps
    interface.
    Therefore: as long as you use the switch as a "switch", no problem.
    But as soon as you want LAN traffic to be "routed", you run into
    serious performance issues because everything has to go in and out
    on the same 10mbps ethernet interface.


    Apart from that: yes, there is a DMZ-Port-Feature (look for "DMZ-Port"
    in the Feature navigator), which is supported by recent IOS versions.
    In my eyes quite a nice feature, I use it at home to separate my
    WLAN-Segment from my LAN... as long as you dont need to much
    performance, no problem.


    Regards,
    Axel



    Walter Roberson wrote:
    > In article <1h0xphq.15t79c1848q9wN%>,
    > Arnoud Helmantel <> wrote:
    > :Is it possible to use the LAN ports of my router as an ethernet router
    > :and use another modem in bridge mode to connect to the Internet?
    >
    > As of a year or two ago, Cisco started supporting "DMZ" on the 83x,
    > in which one of the 4 LAN ports could be severed from the switch
    > group into a different subnet.
    >
    > I have no information as to whether the second LAN so formed is
    > equvilent to the others or is somewhat restricted.
    =?ISO-8859-1?Q?Axel_G=E4rtner?=, Aug 7, 2005
    #3
  4. Axel Gärtner <> wrote:

    > Hi,
    >
    > in my eyes this is a rather bad idea.
    > The internals of the Cisco 83x-Routers are as follows:
    >
    >
    > +-----------+ +--------------------+
    > ----| 5 Port | | Router with |---- DSL etc...
    > ----| Switch |-----| 10mbps Ethernet, |
    > ----| 100mbps | | ADSL etc... |
    > ----| | | |
    > +-----------+ +--------------------+
    > 4x FE
    >
    > The "router" itself has only one 10mbps ethernet-interface.
    > Behind the router, but on the same circuit-board is a 5-port switch.
    > Four of the switchports are connected to the RJ45-ports on the back of
    > the router, however the fifth port is soldered to the "router" 10mbps
    > interface.
    > Therefore: as long as you use the switch as a "switch", no problem.
    > But as soon as you want LAN traffic to be "routed", you run into
    > serious performance issues because everything has to go in and out
    > on the same 10mbps ethernet interface.
    >
    >
    > Apart from that: yes, there is a DMZ-Port-Feature (look for "DMZ-Port"
    > in the Feature navigator), which is supported by recent IOS versions.
    > In my eyes quite a nice feature, I use it at home to separate my
    > WLAN-Segment from my LAN... as long as you dont need to much
    > performance, no problem.
    >
    >
    > Regards,
    > Axel
    >


    It looks like you don't understand what I am trying to do, I am thinking
    if it is possible to create something like this:

    +-----------+ +--------------------+
    -1--| 4p switch | | Router |---- DSL (unused)
    LAN -2--| 100Mbps |<--->| |
    -3--| VLAN1 | | |
    +-----------+ | |
    WAN -4--| VLAN2 |<--->| |
    +-----------+ +--------------------+


    So basically the questions are:

    - is this even possible to do in IOS?
    - is the 83x capable of routing from VLAN1 to VLAN2 at decent speeds?
    ADSL2 can be up to 20/1Mbps I think. (routing over the "<--->"
    connections)

    My router:

    Cisco IOS Software, C837 Software (C837-K9O3SY6-M), Version 12.3(11)T,
    RELEASE SOFTWARE (fc2)

    Cisco C837 (MPC857DSL) processor (revision 0x500) with 44237K/4915K
    bytes of memory.
    Processor board ID AMB0833097L (1943130886), with hardware revision 0000
    CPU rev number 7
    1 Ethernet interface
    4 FastEthernet interfaces
    1 ATM interface
    128K bytes of NVRAM.
    12288K bytes of processor board System flash (Read/Write)
    2048K bytes of processor board Web flash (Read/Write)

    thanks,

    Arnoud


    --
    Please use my first and last name in the address & remove '.invalid'
    Mijn voor- en achternaam gebruiken in het adres zonder '.invalid'
    Arnoud Helmantel, Aug 7, 2005
    #4
  5. Arnoud Helmantel

    Uli Link Guest


    >
    > It looks like you don't understand what I am trying to do, I am thinking
    > if it is possible to create something like this:
    >
    > +-----------+ +--------------------+
    > -1--| 4p switch | | Router |---- DSL (unused)
    > LAN -2--| 100Mbps |<--->| |
    > -3--| VLAN1 | | |
    > +-----------+ | |
    > WAN -4--| VLAN2 |<--->| |
    > +-----------+ +--------------------+
    >
    >
    > So basically the questions are:
    >
    > - is this even possible to do in IOS?


    No. VLAN feature is not available on 83x platform.

    > - is the 83x capable of routing from VLAN1 to VLAN2 at decent speeds?
    > ADSL2 can be up to 20/1Mbps I think. (routing over the "<--->"
    > connections)


    Depends on what decent means. I think 12.3(14)T introduced using the E2
    port (switch port 4) as backup interface. You *can* connect your modem
    there.

    Ethernet FDX is limited to 10Mbps/10Mbps. For more, you'll need a
    FastEthernet interface.
    Since all packets have to go in and out the max throughput is to low for
    datarates requiring ADSL2.

    > My router:
    >
    > Cisco IOS Software, C837 Software (C837-K9O3SY6-M), Version 12.3(11)T,
    > RELEASE SOFTWARE (fc2)
    >
    > Cisco C837 (MPC857DSL) processor (revision 0x500) with 44237K/4915K
    > bytes of memory.


    Bad luck: You have an old 83x with 48MB RAM max.
    For 12.3(14) or 12.4 you'll need 64MB, perhaps the small image (without
    PLUS) does work with 48MB and "memory-size iomem 5".
    Perhaps Cisco finds a way for adding a 32MB SIMM and get it recognized.

    --
    Uli
    Uli Link, Aug 7, 2005
    #5
  6. Uli Link <> wrote:

    > >
    > > It looks like you don't understand what I am trying to do, I am thinking
    > > if it is possible to create something like this:
    > >
    > > +-----------+ +--------------------+
    > > -1--| 4p switch | | Router |---- DSL (unused)
    > > LAN -2--| 100Mbps |<--->| |
    > > -3--| VLAN1 | | |
    > > +-----------+ | |
    > > WAN -4--| VLAN2 |<--->| |
    > > +-----------+ +--------------------+
    > >
    > >
    > > So basically the questions are:
    > >
    > > - is this even possible to do in IOS?

    >
    > No. VLAN feature is not available on 83x platform.


    Ah, too bad...

    > > - is the 83x capable of routing from VLAN1 to VLAN2 at decent speeds?
    > > ADSL2 can be up to 20/1Mbps I think. (routing over the "<--->"
    > > connections)

    >
    > Depends on what decent means. I think 12.3(14)T introduced using the E2
    > port (switch port 4) as backup interface. You *can* connect your modem
    > there.
    >
    > Ethernet FDX is limited to 10Mbps/10Mbps. For more, you'll need a
    > FastEthernet interface.
    > Since all packets have to go in and out the max throughput is to low for
    > datarates requiring ADSL2.


    But, the LAN ethernet ports on the 83x are FastEthernet interfaces. (see
    the previous post).

    > > My router:
    > >
    > > Cisco IOS Software, C837 Software (C837-K9O3SY6-M), Version 12.3(11)T,
    > > RELEASE SOFTWARE (fc2)
    > >
    > > Cisco C837 (MPC857DSL) processor (revision 0x500) with 44237K/4915K
    > > bytes of memory.

    >
    > Bad luck: You have an old 83x with 48MB RAM max.
    > For 12.3(14) or 12.4 you'll need 64MB, perhaps the small image (without
    > PLUS) does work with 48MB and "memory-size iomem 5".
    > Perhaps Cisco finds a way for adding a 32MB SIMM and get it recognized.


    Or perhaps time to simply get a Linksys ethernet router :-(

    Oh well, by selling the 837 I probably can buy four new Linksys routers
    :)

    thanks,

    Arnoud

    --
    Please use my first and last name in the address & remove '.invalid'
    Mijn voor- en achternaam gebruiken in het adres zonder '.invalid'
    Arnoud Helmantel, Aug 7, 2005
    #6
  7. On 07.08.2005 20:11 Arnoud Helmantel wrote


    > So basically the questions are:
    >
    > - is this even possible to do in IOS?


    yes, assign a 2ndary IP address on eth0 and route back to you new WAN
    gateway.

    > - is the 83x capable of routing from VLAN1 to VLAN2 at decent speeds?
    > ADSL2 can be up to 20/1Mbps


    Define decent.

    > I think. (routing over the "<--->" connections)
    >


    Physically there is only one connection. Hence traffic from/to the FE
    ports to/from the WAN have to cross this 10Mbps connection twice.
    Calculate yourself which max thruput you get and if it is "decent" for you.

    Buying a switch would imho make much more sense, but ymmv ...





    Arnold
    --
    Arnold Nipper, AN45
    Arnold Nipper, Aug 7, 2005
    #7
  8. Arnoud Helmantel

    Uli Link Guest

    Arnoud Helmantel schrieb:

    > But, the LAN ethernet ports on the 83x are FastEthernet interfaces. (see
    > the previous post).


    Yes, but when you enable Ethernet 2 it is a Ethernet towards the router.

    --
    Uli
    Uli Link, Aug 7, 2005
    #8
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