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Ip unnumbered loopback0

 
 
AM
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      09-12-2005
As only sometime there are devices connected to Ethernet0 of my router, that interface is often down. I have a VPN built
using LAN behind router but I can not use any service available on the router using that interface. So I can not
connect through the tunnel to the router or use SNMP over the tunnel.

I specified loopback0 with the address of the Etrhernet and I gave the command "ip unnumbered loopback0" to the ethernet.
This was the response

Point-to-point (non-multi-access) interfaces only

and I can not see the above statement in the ethernet 0 section.

Is it correct? Will NAT process work correctly for workstation behind the router?

Thanks,

Alex.
 
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Cen
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      09-12-2005
ip unnumbered command can only be used for point to point link (e.g.
serial)
Ethernet is NOT one of them, as it is a multiaccess media therefore it
cannot borrow the address from loopback


"AM" <(E-Mail Removed)> wrote in message
news:BcjVe.219$(E-Mail Removed)...
> As only sometime there are devices connected to Ethernet0 of my router,
> that interface is often down. I have a VPN built using LAN behind router
> but I can not use any service available on the router using that
> interface. So I can not connect through the tunnel to the router or use
> SNMP over the tunnel.
>
> I specified loopback0 with the address of the Etrhernet and I gave the
> command "ip unnumbered loopback0" to the ethernet.
> This was the response
>
> Point-to-point (non-multi-access) interfaces only
>
> and I can not see the above statement in the ethernet 0 section.
>
> Is it correct? Will NAT process work correctly for workstation behind the
> router?
>
> Thanks,
>
> Alex.



 
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AM
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      09-13-2005
Cen wrote:
> ip unnumbered command can only be used for point to point link (e.g.
> serial)
> Ethernet is NOT one of them, as it is a multiaccess media therefore it
> cannot borrow the address from loopback
>


So how to have ethernet0's address available even if Ethernet0 is down? Or there are no possibilities to do that?

Alex.
 
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Nick Ersdown
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      09-13-2005
You could try using 'no keepalive' under the E0 interface. The interface
will always stay up even if the cable is disconnected.

Regards,

Nick Ersdown
Your real-time, not too serious, view of the latest global IT security
issues.
www.ar53.com


"AM" <(E-Mail Removed)> wrote in message
newsivVe.969$(E-Mail Removed)...
> Cen wrote:
>> ip unnumbered command can only be used for point to point link (e.g.
>> serial)
>> Ethernet is NOT one of them, as it is a multiaccess media therefore it
>> cannot borrow the address from loopback
>>

>
> So how to have ethernet0's address available even if Ethernet0 is down? Or
> there are no possibilities to do that?
>
> Alex.



 
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Vincent C Jones
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      09-13-2005
Except then any other devices on the Ethernet will be unable to
reach the router using the E0 IP address because for them it is
still local. Ditto for any devices which reach that Ethernet to
get to the router via any other routers on that Ethernet.

A far better solution for network management is to configure the
services which must remain up to use the Loopback IP address so that
it can be reached as long as any path remains to the router. For
local devices which are too dumb to use a default gateway to get
to the service, proxy ARP is your friend.

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

In article <dg61jb$1ac$1$(E-Mail Removed)>,
Nick Ersdown <(E-Mail Removed)> wrote:
>You could try using 'no keepalive' under the E0 interface. The interface
>will always stay up even if the cable is disconnected.
>
>Regards,
>
>Nick Ersdown
>
>"AM" <(E-Mail Removed)> wrote in message
>newsivVe.969$(E-Mail Removed)...
>> Cen wrote:
>>> ip unnumbered command can only be used for point to point link (e.g.
>>> serial)
>>> Ethernet is NOT one of them, as it is a multiaccess media therefore it
>>> cannot borrow the address from loopback
>>>

>>
>> So how to have ethernet0's address available even if Ethernet0 is down? Or
>> there are no possibilities to do that?
>>
>> Alex.

 
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AM
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      09-13-2005
Vincent C Jones wrote:
> Except then any other devices on the Ethernet will be unable to
> reach the router using the E0 IP address because for them it is
> still local. Ditto for any devices which reach that Ethernet to
> get to the router via any other routers on that Ethernet.


I must add one more subnet for each VPN tunnel I built

Alex.
 
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AM
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      09-13-2005
Nick Ersdown wrote:

> You could try using 'no keepalive' under the E0 interface. The interface
> will always stay up even if the cable is disconnected.


This tip doesn't work

Alex.
 
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Walter Roberson
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      09-13-2005
In article <iADVe.2088$(E-Mail Removed)>, AM <(E-Mail Removed)> wrote:
:Vincent C Jones wrote:
:> Except then any other devices on the Ethernet will be unable to
:> reach the router using the E0 IP address because for them it is
:> still local. Ditto for any devices which reach that Ethernet to
:> get to the router via any other routers on that Ethernet.

:I must add one more subnet for each VPN tunnel I built

By "tunnel" do you mean "peer" or "security association" ?

All the security associations going to a given peer could be routed
through a common IP address, the route to which being was what was
varying.
--
Ceci, ce n'est pas une idée.
 
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AM
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      09-13-2005
Walter Roberson wrote:

> In article <iADVe.2088$(E-Mail Removed)>, AM <(E-Mail Removed)> wrote:
> :Vincent C Jones wrote:
> :> Except then any other devices on the Ethernet will be unable to
> :> reach the router using the E0 IP address because for them it is
> :> still local. Ditto for any devices which reach that Ethernet to
> :> get to the router via any other routers on that Ethernet.
>
> :I must add one more subnet for each VPN tunnel I built
>
> By "tunnel" do you mean "peer" or "security association" ?


IPsec SA, that where I specify which traffic coming from and going to must be encrypted. I must add also traffic coming
from my LAN to the loopback interface. And I have 30... humpf... Just to standardize all connections, otherwise I need
only one chabge.

Alex.
 
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