ISR 1921 - Dialer Persistent / Dialer Watch

[julrober]

My customer is having an issue (I can supply config if required) where they have a 1921 router with a LTE HWIC and the cellular connection is their only link. The issue is they want this to stay up permanently but it keeps dropping.

I suspect that they need the dialer persistent or the dialer watch list  feature and I have shared with them a number of links with one being

https://www.cisco.com/c/en/us/td/docs/routers/access/interfaces/software/feature/guide/ehwic-4g-ltesw-book.html#con_1334872

Looking at their configuration and their requirement, what is the recommended way of configuring the link to be always on please ?

Also looking at the configuration for the persistent feature above

chat-script lte "" "AT!CALL" TIMEOUT 20 "OK"

interface Cellular0/0/0

ip address negotiated

  encapsulation slip

dialer in-band

dialer pool-member 1

async mode interactive

routing dynamic

interface Dialer1

ip address negotiated

encapsulation slip

dialer pool 1

dialer idle-timeout 0

dialer string lte

dialer persistent

dialer-group 1

What is the difference between the dialer pool and dialer group in practice please , I did find this

9.
dialer pool pool-number
Specify the dialing pool to use for calls to this destination.
10.
dialer-group group-number
Assign the Dialer interface to a dialer group. This applies the interesting traffic definition to the interface

So does this mean that the dialer group command is not needed when using the dialer persistent feature as it doesn’t need interesting traffic ?

Some clarification would be great thank you so I can go back to my customer with a clear approach for them to adopt.

Any help is much appreciated

Kind Regards

Julia

[Cristian Matei]

Hi,

   1. The dialer pool number is what creates the bonding between the physical interface (cellular) and logical interface (dialer), and for this reason the specified number has to match between the Dealer and the physical interface.

   2. Dialer persistent allows the connection to be brought up without waiting for interesting traffic. Dialer group is an option matched by a dialer list, where you identify the interesting traffic which should trigger the connection to be brought up. But none of these options have to do with keeping the session up, but with bringing the session up, which is not your problem.

The session gets disconnected probably due to being idle. You could combine it with a Dialer, configure idle-timeout to be 0 (infinite), as you have it. If it doesn't work, try upgrading the IOS version, or as a workaround, configure an SLA to constantly send some traffic through the Dialer.

interface Cellular0/0/0

  ip address negotiated

  encapsulation slip

  dialer in-band

  dialer pool-member 1

  async mode interactive

  routing dynamic

!

interface Dialer1

ip address negotiated

encapsulation slip

dialer pool 1

dialer idle-timeout 0

dialer string lte

dialer persistent

no dialer-group 1

Regards,

Cristian Matei.

[julrober]

Thank you , answer is very helpful