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I configured "no switchport" with IP address on my 4948 and all is
well when I have something plugged into that interface. (I can ping
the interface address from nodes attached to the VLANs on the switch
and whatever is attached to the L3 interface). BUT, when I unplug
nodes directly connected to the L3 port, I can't ping the L3 port IP
for some reason. Is there something I need to do so that it remains up
even if there are no physical connections to the L3 port?

berkid had written this in response to
http://www.telecom-gear.com/cisco/L3...948-61123-.htm :
unix wrote:





--

Its not possible for phisycal interface to remain up even if its unpluged.
I don't understand why do you need that exactly, but maybe a loopback
interface can solve your problem or using a loopback interface and the ip
unnumbered loopback 0 command on the L3 interface.


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On 27 Apr, 15:55, berkdan_at_freemail_dot...@foo.com (berkid) wrote:
> berkid had written this in response tohttp://www.telecom-gear.com/cisco/L3-interface-on-4948-61123-.htm*:
>
> unix wrote:

> Its not possible for phisycal interface to remain up even if its unpluged..
> I don't understand why do you need that exactly, but maybe a loopback
> interface can solve your problem or using a loopback interface and the ip
> unnumbered loopback 0 command on the L3 interface.

It is I think possible to have a physical interface up
even if nothing is connected.

int x
no keepalive

Hmmm. I just tried on an 877. Did not work on the
switch ports. They are unusual though.

Not usually something you would ever want to do though.
For example RIP could advertise unreachable networks.

On Apr 27, 11:00*am, bod43 <Bo...@hotmail.co.uk> wrote:
> On 27 Apr, 15:55, berkdan_at_freemail_dot...@foo.com (berkid) wrote:
>
> > berkid had written this in response tohttp://www.telecom-gear.com/cisco/L3-interface-on-4948-61123-.htm*:
>
> > unix wrote:
> > Its not possible for phisycal interface to remain up even if its unpluged.
> > I don't understand why do you need that exactly, but maybe a loopback
> > interface can solve your problem or using a loopback interface and the ip
> > unnumbered loopback 0 command on the L3 interface.
>
> It is I think possible to have *a physical interface up
> even if nothing is connected.
>
> int x
> *no keepalive
>
> Hmmm. I just tried on an 877. Did not work on the
> switch ports. They are unusual though.
>
> Not usually something you would ever want to do though.
> For example RIP could advertise unreachable networks.

Let me clarify. Let's say my L3 port is assigned 10.10.10.11 and I
have a PC directly connected to that interface with ip
10.10.10.12. From a VLAN on that switch, I can ping 10.10.10.11 and
10.10.10.12. When I unplug the PC, I can't ping the L3 interface
address any more. There has to be a way to keep it up since it's just
a virtual ip similar to VLAN ip address that we define when we want to
enable VLAN routing. Makes sense?

On 28 Apr, 05:27, unix <unix...@yahoo.com> wrote:
> On Apr 27, 11:00*am, bod43 <Bo...@hotmail.co.uk> wrote:
>
>
>
> > On 27 Apr, 15:55, berkdan_at_freemail_dot...@foo.com (berkid) wrote:
>
> > > berkid had written this in response tohttp://www.telecom-gear.com/cisco/L3-interface-on-4948-61123-.htm*:
>
> > > unix wrote:
> > > Its not possible for phisycal interface to remain up even if its unpluged.
> > > I don't understand why do you need that exactly, but maybe a loopback
> > > interface can solve your problem or using a loopback interface and the ip
> > > unnumbered loopback 0 command on the L3 interface.
>
> > It is I think possible to have *a physical interface up
> > even if nothing is connected.
>
> > int x
> > *no keepalive
>
> > Hmmm. I just tried on an 877. Did not work on the
> > switch ports. They are unusual though.
>
> > Not usually something you would ever want to do though.
> > For example RIP could advertise unreachable networks.
>
> Let me clarify. Let's say my L3 port is assigned 10.10.10.11 and I
> have a PC directly connected to that interface with ip
> 10.10.10.12. * *From a VLAN on that switch, I can ping 10.10.10.11 and
> 10.10.10.12. When I unplug the PC, I can't ping the L3 interface
> address any more. There has to be a way to keep it up since it's just
> a virtual ip similar to VLAN ip address that we define when we want to
> enable VLAN routing. Makes sense?

Yes. berkid and I got it first time round too

This is the design behaviour. Why would you want anything else?

Use berkids solution which will looks pretty good to me
if it's what you want. I mentioned the no keepalive
not because I think it might be intrinsically better but because
it might for some reason suit you better. It does work on
some interfaces but I forget the details. I don't have access to a
4948 (or a 4500 which amounts to the same thing) to play with.

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