Dialer Interfaces

Discussion in 'Cisco' started by Darren Green, Jan 27, 2005.

  1. Darren Green

    Darren Green Guest

    One of my colleagues is configuring a 1721 with 1 x ADSL (Dialer 0) and ISDN
    Backup (Dialer 10).

    When the ADSL fails we would like to failover to ISDN.

    We have a static route (192.168.X.X 255.255.0.0 Dialer 0) and a default
    route (0.0.0.0 0.0.0.0 Dialer 10)

    Assuming the ADSL fails, how do you make sure that the 192.168.X.X route is
    removed from the routing table so that the default route vial Dialer 10 is
    used.

    Hope that makes sense.

    Regards
    --
    Darren Green
    Darren Green, Jan 27, 2005
    #1
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  2. Darren Green

    SysAdm Guest

    "Darren Green" <> wrote in message
    news:ctbgj1$efq$...
    > One of my colleagues is configuring a 1721 with 1 x ADSL (Dialer 0) and

    ISDN
    > Backup (Dialer 10).
    >
    > When the ADSL fails we would like to failover to ISDN.
    >
    > We have a static route (192.168.X.X 255.255.0.0 Dialer 0) and a default
    > route (0.0.0.0 0.0.0.0 Dialer 10)
    >
    > Assuming the ADSL fails, how do you make sure that the 192.168.X.X route

    is
    > removed from the routing table so that the default route vial Dialer 10 is
    > used.

    <snip>

    take a look at the "Backup Interface" command.

    eg.
    int dialer10
    backup delay 5 20
    backup interface dialer0

    SysAdm
    SysAdm, Jan 28, 2005
    #2
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  3. Darren Green

    Darren Green Guest

    Thanks SysAdmin.

    I am familiar with this command. From what my colleague said, the problem
    seems to be that the Dialer Interface is logical and therefore if the ADSL
    port fails the Dialer 0 interface still stays up, hence the route doesn't
    get removed from the routing table.

    He needs this to happen to stop the route going into a black hole before the
    ISDN kicks in. There is no routing protocol just static / default routing.

    Regards

    Darren.


    "SysAdm" <widge_it@_remove_btinternet.com> wrote in message
    news:ctc3m1$nnj$...
    >
    > "Darren Green" <> wrote in message
    > news:ctbgj1$efq$...
    > > One of my colleagues is configuring a 1721 with 1 x ADSL (Dialer 0) and

    > ISDN
    > > Backup (Dialer 10).
    > >
    > > When the ADSL fails we would like to failover to ISDN.
    > >
    > > We have a static route (192.168.X.X 255.255.0.0 Dialer 0) and a default
    > > route (0.0.0.0 0.0.0.0 Dialer 10)
    > >
    > > Assuming the ADSL fails, how do you make sure that the 192.168.X.X route

    > is
    > > removed from the routing table so that the default route vial Dialer 10

    is
    > > used.

    > <snip>
    >
    > take a look at the "Backup Interface" command.
    >
    > eg.
    > int dialer10
    > backup delay 5 20
    > backup interface dialer0
    >
    > SysAdm
    >
    >
    Darren Green, Jan 28, 2005
    #3
  4. You are right !!! The backup interface command wont do any good when
    configured on Dialer interface. The dialer interface always remains in
    UP state and the ISDN will never fire. Actually two solutions exist

    1. If you are using Cisco 1700/2600/3600 with ADSL WIC with PPPoE/PPPoA
    or any form of bridging, then you can configure backup interface
    command under ATM X/Y interface. This is a physical interface and
    reflects status of ADSL connection.

    2. You can use dynamic routing protocol to sense the ADSL connectivity.
    OSPF is the best option.

    Regards
    Jay :eek:)
    Jayesh Sharma, Jan 28, 2005
    #4
  5. In article <ctbgj1$efq$>,
    Darren Green <> wrote:
    >One of my colleagues is configuring a 1721 with 1 x ADSL (Dialer 0) and ISDN
    >Backup (Dialer 10).
    >
    >When the ADSL fails we would like to failover to ISDN.
    >
    >We have a static route (192.168.X.X 255.255.0.0 Dialer 0) and a default
    >route (0.0.0.0 0.0.0.0 Dialer 10)
    >
    >Assuming the ADSL fails, how do you make sure that the 192.168.X.X route is
    >removed from the routing table so that the default route vial Dialer 10 is
    >used.
    >
    >Hope that makes sense.
    >
    >Regards
    >--
    >Darren Green


    Since dialer interfaces never go down, you need to use "ping based
    routing" to detect when ADSL has failed and change the default route.
    Search www.cisco.com for "ping based routing" and/or "response time
    recorder" (RTR). This is non-trivial if you are also doing NAT,
    because while the RTR facilities will change the route, they will not
    clear the translation table, so unless the same translations are used
    for both routes, you have a major challenge (there is a workaround,
    but it is incredibly ugly--you might want to consider using a SOHO
    router instead, where ping based routing and NAT failover are part
    of the standard package, look at the LinkSys RV042, but keep in mind
    that the SOHO routers don't support ISDN like a 17xx does.

    Good luck and have fun!
    --
    Vincent C Jones, Consultant Expert advice and a helping hand
    Networking Unlimited, Inc. for those who want to manage and
    Tenafly, NJ Phone: 201 568-7810 control their networking destiny
    http://www.networkingunlimited.com
    Vincent C Jones, Jan 28, 2005
    #5
  6. Darren Green

    SysAdm Guest

    "Vincent C Jones" <> wrote in message
    news:ctdv60$858$...
    > In article <ctbgj1$efq$>,
    > Darren Green <> wrote:
    > >One of my colleagues is configuring a 1721 with 1 x ADSL (Dialer 0) and

    ISDN
    > >Backup (Dialer 10).
    > >
    > >When the ADSL fails we would like to failover to ISDN.
    > >
    > >We have a static route (192.168.X.X 255.255.0.0 Dialer 0) and a default
    > >route (0.0.0.0 0.0.0.0 Dialer 10)
    > >
    > >Assuming the ADSL fails, how do you make sure that the 192.168.X.X route

    is
    > >removed from the routing table so that the default route vial Dialer 10

    is
    > >used.
    > >
    > >Hope that makes sense.
    > >
    > >Regards
    > >--
    > >Darren Green

    >
    > Since dialer interfaces never go down, you need to use "ping based
    > routing" to detect when ADSL has failed and change the default route.
    > Search www.cisco.com for "ping based routing" and/or "response time
    > recorder" (RTR). This is non-trivial if you are also doing NAT,
    > because while the RTR facilities will change the route, they will not
    > clear the translation table, so unless the same translations are used
    > for both routes, you have a major challenge (there is a workaround,
    > but it is incredibly ugly--you might want to consider using a SOHO
    > router instead, where ping based routing and NAT failover are part
    > of the standard package, look at the LinkSys RV042, but keep in mind
    > that the SOHO routers don't support ISDN like a 17xx does.



    thanks for that Vincent. to be honest I hadnt checked if the dialer goes
    down or not. I know that with Serial Int's the same thing occurs, but if
    you create sub-ints and they will go down/down if the main int goes down. I
    just didnt check to see if the same occured with a bri/dsl int and
    corresponding dialer ints.

    thks for the info
    SysAdm
    SysAdm, Jan 29, 2005
    #6
  7. Darren Green

    SysAdm Guest

    "Jayesh Sharma" <> wrote in message
    news:...
    > You are right !!! The backup interface command wont do any good when
    > configured on Dialer interface. The dialer interface always remains in
    > UP state and the ISDN will never fire. Actually two solutions exist
    >
    > 1. If you are using Cisco 1700/2600/3600 with ADSL WIC with PPPoE/PPPoA
    > or any form of bridging, then you can configure backup interface
    > command under ATM X/Y interface. This is a physical interface and
    > reflects status of ADSL connection.


    I didnt offer the option of ospf demand circuits as it looks as if his adsl
    cnx is to his service provider. I doubt they'd offer this service at their
    end -- maybe the OP could ask...

    In light of Vincents post, take a look at this
    http://www.cisco.com/en/US/tech/tk364/technologies_configuration_example09186a0080211f5c.shtml

    SysAdm
    SysAdm, Jan 29, 2005
    #7
  8. Have a look at the folowing article
    http://www.cisco.com/univercd/cc/td...123/123newft/123limit/123x/123xe/dbackupx.htm
    cheers, bernard
    Darren Green wrote:

    > One of my colleagues is configuring a 1721 with 1 x ADSL (Dialer 0) and
    > ISDN Backup (Dialer 10).
    >
    > When the ADSL fails we would like to failover to ISDN.
    >
    > We have a static route (192.168.X.X 255.255.0.0 Dialer 0) and a default
    > route (0.0.0.0 0.0.0.0 Dialer 10)
    >
    > Assuming the ADSL fails, how do you make sure that the 192.168.X.X route
    > is removed from the routing table so that the default route vial Dialer 10
    > is used.
    >
    > Hope that makes sense.
    >
    > Regards
    > --
    > Darren Green
    Bernard van de Koppel, Feb 6, 2005
    #8
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