broke connection on route change - Suse

This is a discussion on broke connection on route change - Suse ; Hi all. I set up a VPN using two SUSE 10.0 Each SuSE box has two dsl connection to the other SuSE box. Dsl1 is the primary connection and dsl0 is the backup link. So, each box has three ethernet ...

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Thread: broke connection on route change

  1. broke connection on route change

    Hi all.

    I set up a VPN using two SUSE 10.0
    Each SuSE box has two dsl connection to the other SuSE box. Dsl1 is
    the primary connection and dsl0 is the backup link. So, each box has
    three ethernet cards: one for dsl1, another for dsl0 and another is
    the internal interface.

    Each PC on any LAN has the internal IP of the SuSE box as gateway, so
    I can reach any PC of any LAN from any PC of the other LAN.

    So, the basic connection works.

    In order to manage the primary link (dsl1) and the backup one (dsl0),
    I did two routes on the SuSE box:

    route add -net x.y.z.0/24 dev dsl1
    route add -net x.y.z.0/24 metric 1 dev dsl0

    so it uses dsl0 if dsl1 is not available.

    Now the problem is that I have remote clients that connect to telnet
    sessions on a server.
    So this happens:

    1) the client connects to server on the primary connection. The route
    is:
    client (telnet session) --> SuSE --> dsl1 --> remote Server (port 23)

    2) the primary link fails. The route becomes:
    client (telnet session) --> SuSE --> dsl0 --> remote Server (port 23)

    From the time 1 to the time 2 the session telnet is resetted, even if
    it takes just 1 second.

    I don't think it's a timeout problem, because I did this test:
    1) from a local PC I connected to a telnet session
    2) I unplugged the ethernet cable
    3) after 20 seconds I plugged in the ethernet cable
    4) the session telnet was not resetted

    So it is the switch from one route to another that breaks the
    connection

    Maybe it can be a firewall problem, but if I do

    SuSEfirewall2 stop

    the routing does not work at all.

    Even if i set
    FW_STOP_KEEP_ROUTING_STATE="yes"
    when I shut down the firewall it keeps active connections, but I can't
    create new connections.

    So I cannot test the VPN without the firewall.

    So, how it is possible to change the route without break the
    connection?

    Thanks to all.

  2. Re: broke connection on route change

    On Tue, 09 Sep 2008 00:11:39 -0700, TT typed this message:

    > Hi all.
    >
    > I set up a VPN using two SUSE 10.0
    > Each SuSE box has two dsl connection to the other SuSE box. Dsl1 is the
    > primary connection and dsl0 is the backup link. So, each box has three
    > ethernet cards: one for dsl1, another for dsl0 and another is the
    > internal interface.
    >
    > Each PC on any LAN has the internal IP of the SuSE box as gateway, so I
    > can reach any PC of any LAN from any PC of the other LAN.
    >
    > So, the basic connection works.
    >
    > In order to manage the primary link (dsl1) and the backup one (dsl0), I
    > did two routes on the SuSE box:
    >
    > route add -net x.y.z.0/24 dev dsl1
    > route add -net x.y.z.0/24 metric 1 dev dsl0
    >
    > so it uses dsl0 if dsl1 is not available.
    >
    > Now the problem is that I have remote clients that connect to telnet
    > sessions on a server.
    > So this happens:
    >
    > 1) the client connects to server on the primary connection. The route
    > is:
    > client (telnet session) --> SuSE --> dsl1 --> remote Server (port 23)
    >
    > 2) the primary link fails. The route becomes: client (telnet session)
    > --> SuSE --> dsl0 --> remote Server (port 23)
    >
    > From the time 1 to the time 2 the session telnet is resetted, even if it
    > takes just 1 second.
    >
    > I don't think it's a timeout problem, because I did this test: 1) from a
    > local PC I connected to a telnet session 2) I unplugged the ethernet
    > cable
    > 3) after 20 seconds I plugged in the ethernet cable 4) the session
    > telnet was not resetted
    >
    > So it is the switch from one route to another that breaks the connection
    >
    > Maybe it can be a firewall problem, but if I do
    >
    > SuSEfirewall2 stop
    >
    > the routing does not work at all.
    >
    > Even if i set
    > FW_STOP_KEEP_ROUTING_STATE="yes"
    > when I shut down the firewall it keeps active connections, but I can't
    > create new connections.
    >
    > So I cannot test the VPN without the firewall.
    >
    > So, how it is possible to change the route without break the connection?
    >
    > Thanks to all.


    As I understand it, the problem isn't with the routing the problem is
    with the dsl connection. Your timeout test does not test the switch it
    just tests the current DSL connection, ie, the connection assumes bad or
    lost packets but continues to wait for acknowledgments.
    When the actual DSL connection is switched it establishes the new route
    which takes time.

    IOW, I think route 192.x.x.1 to 195.x.x.2 is can be severed but resumes
    when reconnected, but 192.x.x.1 to 195.x.x.5 is a new route entirely and
    should show and entirely different traceroute.

  3. Re: broke connection on route change

    On 9 Set, 22:50, noi ance wrote:
    > As I understand it, the problem isn't with the routing the problem is
    > with the dsl connection. *Your timeout test does not test the switch it
    > just tests the current DSL connection, ie, the connection assumes bad or
    > lost packets but continues to wait for acknowledgments. *
    > When the actual DSL connection is switched it establishes the new route
    > which takes time. *


    You're right, this is what happens.

    I have 2 routes:
    1) route add -net x.y.z.0/24 dev dsl1
    2) route add -net x.y.z.0/24 metric 1 dev dsl0

    Normally, it uses route 1)
    Even if dsl1 link is bad it does not switch to route 2) and so the
    connection is broke
    But, if I do ifdown dsl1, the route 1) is deleted and it begins to use
    route 2)
    In the meanwhile, remote terminals lose connection to server.

    So, the question is:

    Why it uses route 1) even if the link is bad?

    In fact, it uses route 2) only when route 1) is deleted because dev
    dsl1 goes down.

    >
    > IOW, I think route 192.x.x.1 to 195.x.x.2 is can be severed but resumes
    > when reconnected, but 192.x.x.1 to 195.x.x.5 is a new route entirely and
    > should show and entirely different traceroute.


    I did not understand, sorry.

    Thank You.

  4. Re: broke connection on route change

    On Tue, 09 Sep 2008 15:35:58 -0700, TT typed this message:

    > On 9 Set, 22:50, noi ance wrote:
    >> As I understand it, the problem isn't with the routing the problem is
    >> with the dsl connection. *Your timeout test does not test the switch it
    >> just tests the current DSL connection, ie, the connection assumes bad
    >> or lost packets but continues to wait for acknowledgments. When the
    >> actual DSL connection is switched it establishes the new route which
    >> takes time.

    >
    > You're right, this is what happens.
    >
    > I have 2 routes:
    > 1) route add -net x.y.z.0/24 dev dsl1 2) route add -net x.y.z.0/24
    > metric 1 dev dsl0
    >
    > Normally, it uses route 1)
    > Even if dsl1 link is bad it does not switch to route 2) and so the
    > connection is broke
    > But, if I do ifdown dsl1, the route 1) is deleted and it begins to use
    > route 2)
    > In the meanwhile, remote terminals lose connection to server.
    >
    > So, the question is:
    >
    > Why it uses route 1) even if the link is bad?
    >
    > In fact, it uses route 2) only when route 1) is deleted because dev dsl1
    > goes down.
    >
    > Thank You.



    Its not an elegant solution but I suggest you add 1 or 2 PCs on the
    network to use the route2 as primary with route 1 as secondary. That
    would establish and keep route2 open and reduce the dsl fallover time.


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