Difference between Dialer-Watch and Dialer-Persistent in Cellular Configuration of Cisco Router e.g 881G?

[rameshprabhu]

This is my first ever question, Sorry if I missed anything to Add-in to describe about my Question.

[Philip D'Ath]

I think "watch" causes the interface to come up if a route disappears from the routing table, and "persistent" causes the interface to always be up regardless.

[rameshprabhu]

Hi Philip

 First of all thanks very much for answering my question.

you mean to say for "Persistent" the dialer would always dial regardless of route check?

[Philip D'Ath]

Yes.

[rameshprabhu]

Philip

 Why we need a Watch-list for Cellular Connection, Is it necessary?

Or simply the below config work?

!
interface Cellular0
 ip address negotiated
 ip virtual-reassembly in
 encapsulation slip
 dialer in-band
 dialer string lte
 dialer-group 1
 async mode interactive
 routing dynamic

!

dialer-list 1 protocol ip permit

thanks.

[Philip D'Ath]

It may be that 3G is very expensive, you you may only want to bring the interface online when the main interface has dropped.

If may be you have a private cellular WAN, and you only want to bring it online when the route to the WAN drops on the machine interface.

[rameshprabhu]

I have a private cellular WAN, and its the primary and I always wanted to keep it up regardless of any route check.

In that case will the above config work?

[Philip D'Ath]

It will stay up - as long as their is "ip" traffic flowing over it.

[rameshprabhu]

Here is my issue,

Does the cellular interface go down, if the router is standby or no IP traffic coming in?

[Philip D'Ath]

Yes.  A real simple solution which I have used before is to enable NTP, and configure NTP time synchronisation to run over the interface.  Then there will always be a trickle of traffic.

Another option is to bind it to a Dialer interface and make it "permanent". 

I prefer the NTP approach.  You can sync against your hub router.

[wireman84]

Could utilize a dialer interface:

!
interface Cellular0
ip address negotiated
ip virtual-reassembly in
encapsulation slip
dialer in-band
dialer string lte
async mode interactive
routing dynamic
dialer pool-member 1
!
interface Dialer1
ip address negotiated
dialer pool 1
dialer idle-timeout 0
dialer string lte
! Will pin the cellular connection without traffic
dialer persistent
no cdp enable