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RE: ISDN questions. posted 10/11/2005
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Hi Dustin,

It doesn't matter whether you configure End to End keep alive. The physical
interface will never go down unless it lose communition with the switch. So
even if you have all DLCI status to down, that interface still in the
upstate.

Below is my test lab

R4 - R5 over Frame-relay and ISDN backup. 

Rack1R4#show run int s0/0 
Building configuration...

Current configuration : 592 bytes
!
interface Serial0/0
 ip address 176.1.145.4 255.255.255.0
 encapsulation frame-relay
 backup interface bri0/0
 ip ospf hello-interval 2
 ip ospf priority 0
 no fair-queue
 frame-relay map ip 176.1.145.5 405 broadcast
 frame-relay interface-dlci 405
  class DLCI-405
 no frame-relay inverse-arp

Rack1R4#show frame pvc | i INTERFACE
DLCI = 405, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0

Rack1R4#show backup
Primary Interface   Secondary Interface   Status
-----------------   -------------------   ------
Serial0/0           BRI0/0                normal operation



Now add the EEK

Rack1R4#show run map-class
Building configuration...

Current configuration:
!
map-class frame-relay DLCI-405
 frame-relay end-to-end keepalive mode request
End

I purpsosely not configuring the EEK on R5 so the status of the DLCI should
be down

Rack1R4#show frame pvc 405 | i STATUS
DLCI = 405, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE (EEK DOWN), INTERFACE =
Serial0/0


The bri0/0 still in standby mode and the physical still up

Rack1R4#show backup
Primary Interface   Secondary Interface   Status
-----------------   -------------------   ------
Serial0/0           BRI0/0                normal operation


Rack1R4#show int s0/0 | i line protocol
Serial0/0 is up, line protocol is up

So I guess the backup interface on the physical command is not really useful
in the real world and the lab may tricked you with it.

Hope this helps.

Anh Tran



-----Original Message-----
From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf Of
dusth@xxxxxxxxxxx
Sent: Monday, 10 October 2005 11:53 PM
To: Anh P Tran; 'Arun Arumuganainar'; 'Lee Donald'; 'Stefan Grey';
ccielab@xxxxxxxxxxxxxx
Subject: RE: ISDN questions.

So if you have backup interface configure under the physicall frame
interface, it's a better idea to configure end-to-end keepalive?
Dustin

-------------- Original message -------------- 

> Hi All,
> 
> In addition to Arun note, with frame-relay the only feasible way to 
> use backup is using the sub-interface.
> 
> Point-to-Point : as long as the DLCI status go to Inactive or Deleted 
> the sub-int will go down With multi-point however, all dlci's under 
> that interface must go to Inactive or deleted.
> 
> With the main interface, it will be up regardless of the status of 
> DLCIs as it is talking via LMI to the switch.
> 
> Regards,
> 
> Anh Tran
> 
> -----Original Message-----
> From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf 
> Of Arun Arumuganainar
> Sent: Saturday, 8 October 2005 1:14 AM
> To: Lee Donald; 'Stefan Grey'; ccielab@xxxxxxxxxxxxxx
> Subject: Re: ISDN questions. 
> 
> Lee is correct . 
> 
> For "Backup interface" command to work you need to have your primary 
> interface in down-down state and not admin down state .
> 
> However to verify this . You can do the following . 
> 
> 1) Give shut on the remote side . Or
> 2) give no keepalive on the remote side . 
> 
> Pls. Note : If you are running Frame Relay both the techniques will 
> not work unless and until FR switch is co-operating . In CCIE lab 
> scenario if the above methods did not bring your interface down then 
> pls. resort to End-to-end Keep alive .
> 
> Pls. Note : Here is key is to make your router think remote side or 
> the serial link is down . If that works , then your configuration will 
> certainly work when network really goes down !!!
> 
> Thanks and Regards
> Arun
> ----- Original Message -----
> From: "Lee Donald" 
> To: "'Stefan Grey'" ;
> Sent: Friday, October 07, 2005 8:30 PM
> Subject: RE: ISDN questions. 
> 
> 
> > Stefan,
> > 
> > The isdn interface will remain in standby mode until the the ser0/0 
> > is
> down,
> > not admin down. 
> > 
> > Pull the plug out! 
> > 
> > Regards
> > 
> > Lee. 
> > 
> > 
> > 
> > -----Original Message-----
> > From: Stefan Grey [mailto:examplebrain@xxxxxxxxxxx]
> > Sent: Friday, October 07, 2005 3:47 PM
> > To: ccielab@xxxxxxxxxxxxxx
> > Subject: ISDN questions. 
> > 
> > Just don't understand. 
> > 
> > 
> > R1 - R2. Between them int ISDN. 
> > 
> > 1. When I configure backup between them. 
> > Interface s0/0
> > backup interface dialer 0. 
> > 
> > dialer 0 is getting to the standby mode. 
> > When I type
> > interface s0/0
> > shut
> > dialer 0 is still in standby mode. 
> > a) Why?? As I understand it should get out from standby mode
> automatically?? 
> > 
> > Shouldn't it?? 
> > 
> > b) Theoretically if we want to backup both serial links on R1 and R2. 
> > R1: 
> > int s0/0
> > backupinterface dialer 0
> > 
> > R2: 
> > int s0/0
> > backup interface dialer 0
> > 
> > if for example we shut down only the interface of s0/0 of R1. Should 
> > the connection be up between both routers. Could we by backup 
> > interface functions in this way backup 2 links.
> > 
> > Thanks a lot. 
> > 
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