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New Member

DDR on serial line - problem with reconnection

Dear Sir!

I've point-to-point link between two routers with such configuration:

R1---R2

R1:

hostname R1

username R2 password cisco

int s0

ip address 1.1.1.1 255.255.255.0

encapsulation ppp

ppp authentication chap

dialer in-band

dialer map ip 1.1.1.2 name R2 broadcast

dialer-group 1

ppp direction callout

dialer-list 1 protocol ip permit

R2:

hostname R2

username R1 password cisco

int s0

ip address 1.1.1.2 255.255.255.0

encapsulation ppp

ppp authentication chap

dialer in-band

dialer map ip 1.1.1.1 name R1 broadcast

dialer-group 1

dialer-list 1 protocol ip permit

Q1: I've check it: DDR works & I can ping 1.1.1.1 from R2 or can ping 1.1.1.2

from R1, but I can't ping 1.1.1.1 from R1 or 1.1.1.2 from R2.

Why?

Q2: When I no generate any traffic during some time, then DDR disconnects

the call (after dialer idle-timeout = 120s default, as I suppose).

After that I can't, for example, ping 1.1.1.2 from R1 or ping 1.1.1.1 from R2.

Why DDR not make the call automatically?

Using what IOS command, can I make the DDR call manually?

Best regards,

Nick

2 REPLIES
Bronze

Re: DDR on serial line - problem with reconnection

1. If you want to ping yourself (which doesn't make a lot of sense, it doesn't tell you anything more than when you ping the remote) you need to add a dialer map with your own address. And host addresses off the serial network address need their own dialer map to be reachable.

2. DDR does not call automatically; it requires interesting traffic. If you want the line to be up all the time, use an idle timer of 0. If you want to dial without the requirement for interesting traffic, you would have to use Dialer Watch (as a hack of sorts, since this would not be for a backup situation).

Note that you should remove the command "ppp direction callout"; the router will figure out the direction automatically.

New Member

Re: DDR on serial line - problem with reconnection

Mark!

As concern of my Q2:

1. If I remove the command "ppp direction callout" in the example above, "the router will connect for a moment and then disconnect" - as Cisco says - and no DDR connection will establish - as I check up in my lab.

2. Of course, there are "interesting" traffic, when I ping 1.1.1.2 from R1.

But the problem:

Q3: When the line are in idle-state, when interesting traffic arrives on R1's interface s0, DDR not make a call in the scheme above (DDR on synchronous serial). Why?

May be, it's Cisco IOS bug?

Q4:Why DDR not make the call automatically in the scheme above?

Q5: How can I make the call manually in such example?

Best regards,

Nick

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