Comments within and below.
First, I noted that you used the backup interface command on a
physical interface. Have you considered the idea of using
dialer interfaces as the backup interface? When you do this,
it offers you a little bit more flexibility. For example, I
noted that your serial interface is a 128kbps link. You may
want to explore the possibility of using a dialer interface for
two purposes. One purpose would be to act as a backup
interface. Another purpose could be to use it for additional
bandwidth if your primary serial interface gets congested.
> Hello all.
> I have 2 routers connected using leased line.Now I am trying
to put a
> ISDN
> backup ,but the backup line does not come up.
> The status of ISDN line when the serial int. is up ,is
> BRI2/2 is standby mode, line protocol is down
> and should change to up upon going the serial line down but
it's status
> remain unchanged even the serial link goes down .
You are correct. The issue is one of troubleshooting.
Assuming you have a primary link filure, your backup interface
should go active (up and up) after a 5 second delay that you
configured. According to you this is not happening. You have
not mentioned what troubleshooting steps you have taken. When
you remove the backup interface command from the primary
interface, what is the output from "show isdn status"? Are
layers 1 and 2 good? Assuming they are good, when you place
the backup interface command back on the primary interface,
what happens when you do a "debug dialer and a debug ppp neg"
after the primary link has been made to fail. Assuming you had
a "dialer-list 1 protocol ip permit" statement near the end of
your config [note- you didn't post your entire config, so I am
guessing here] you should get a call placed to the other side.
More below...
> I have configued the serial int with
> backup interface BRI2/2
> backup delay 5 10
> commands . Also i tried to simulate the situation by putting
the modem
> at
> Router A off to trigger the backup ISDN call but it does not
happen and
> the
> ISDN status remain in standyby mode only.
> Can anybody help whether anyadditional command needs to be
put up in
> either
> Serial or Bri interfaces?
> I am giving here th configuration of both the routers,
> routerA#
>
> interface BRI2/2
> description "Backup connectivity "
> ip address 172.16.128.49 255.255.255.252
> no ip directed-broadcast
> encapsulation ppp
> dialer map ip 172.16.128.50 name routerB xxxxx
> dialer-group 2
> isdn switch-type basic-net3
I noted that you set your encapsulation to ppp. That is fine.
One of the many/several options for ppp is authentication. You
indicated in your dialer map statement that you will be doing
authentication by use of the "name" command. Unfortunately
however, you have not specified what method is to be used on
either end of the link. I would start with "ppp auth chap".
It ends to be more secure.
> interface Serial1/3
> description "Leased link to RouterB"
> bandwidth 128
> backup delay 5 10
> backup interface BRI2/2
> ip address 172.16.128.17 255.255.255.252
> no ip directed-broadcast
> no ip route-cache
> no ip mroute-cache
How are you actually testing this? Since you didn't supply a
full config, this is not readily apparent. For example, is
there a LAN on the other side of router B? If so, what is the
network address of the LAN interface? Where is the static (or
other) route that points to this network? When you test your
reachability, do you ping the other side of the WAN link, or
the other side of the LAN network on router B?
> RouterB#
> interface BRI1/2
> description "Backup connectivity for RouterA
> ip address 172.16.128.50 255.255.255.252
> encapsulation ppp
> no logging event subif-link-status
> dialer idle-timeout 3000
> dialer wait-for-carrier-time 60
> dialer map ip 172.16.128.49 name routerB YYYYYYY
> dialer-group 1
> no fair-queue
Here there is an additional problem. Look at the name command
two lines above. The host name following the name command
should be the target you are trying to authenticate, not
yourself. Also, since you didn't post your entire config, I
have no way of knowing whether you set the username/password
lists for both routers. They would look like this and appear
in the global config near the top:
user RouterA pass sameone
user RouterB pass sameone
Note the passwords are the same, also referred to as a "shared
secret".
>
> interface Serial0/0
> ip address 172.16.128.18 255.255.255.252
> logging event subif-link-status
> bandwidth 128
>
> hold-queue 75 in
>
>
> Thanks in advance for help
> Regards
>
> Bware
This post has gotten kind of long. I will see if I can post an
improved/enhanced config in a separate post, possibly later
today as time permits.
HTH,
Paul Werner
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