Dialer Interfaces - trying to understand

[vv0bbLeS]

Hello all,

Trying to get a better understanding of Dialer Interfaces. I know these can be used with protocols such as PPP, but I still have some questions like:

• What is the point of using Dialer interfaces, i.e. what can they do that other interface types can't ?
• Are Dialer interfaces just a holdover from the old telephony days, and we've just found new ways to use them today ? Or are they still considered a "modern" type of interface ?
• This may be answered from the above question answers, but can Dialer interfaces be used with other protocols besides PPP ?
• Can Dialer Groups be used without Dialer Interfaces ?
  • ( I've seen Dialer Groups configured on Cellular interfaces before, but there was no Dialer Interface configured on the router. )

Thanks in advance!

[Georg Pauwen · Accepted solution]

Hello,

--> What is the point of using Dialer interfaces, i.e. what can they do that other interface types can't ?

Dialer interfaces support PAP/CHAP auuthentication, which is frequently used in order to authenticate towards an ISP. Physical interfaces cannot do authentication

--> Are Dialer interfaces just a holdover from the old telephony days, and we've just found new ways to use them today ? Or are they still considered a "modern" type of interface ?

Dialer interfaces are still very much in use. They indeed originated in the 'old' (ISDN) days

--> This may be answered from the above question answers, but can Dialer interfaces be used with other protocols besides PPP ?

Dialer interfaces can do PPP/SLIP only

--> Can Dialer Groups be used without Dialer Interfaces ?
( I've seen Dialer Groups configured on Cellular interfaces before, but there was no Dialer Interface configured on the router. )

Dialer groups can be configured on physical interfaces (cellular/async) as well.

[Giuseppe Larosa · Accepted solution]

Hello @vv0bbLeS ,

>> What is the point of using Dialer interfaces, i.e. what can they do that other interface types can't ?

Dialer interfaces had been introduced in the dial-up era and in ISDN access, they provide an abstraction layer from the physical interfaces that actually perform the dial-up. In the past this was useful for example to add additional B channels ( 64 kbps each) to a connection based on traffic usage for example.

Dialer interfaces have found usage for PPPoE or other forms like PPPoA or PPPoEoA in broadband access.

They have still use in this scenario.

>> Are Dialer interfaces just a holdover from the old telephony days, and we've just found new ways to use them today ? Or are they still considered a "modern" type of interface ?

As answered above they come from the old telephony days but they have found application in broadband access so they are still in use and not only legacy.

>> This may be answered from the above question answers, but can Dialer interfaces be used with other protocols besides PPP ?

As far as I know they are used only with PPP or other PPPoE or other broadband variants they would not make sense to be used with another encapsulation like for example cisco HDLC or Frame Relay.

>> Can Dialer Groups be used without Dialer Interfaces ?

Yes in legacy interfaces like BRI ISDN that have two B channels and one D channel or async serial

>> I've seen Dialer Groups configured on Cellular interfaces before, but there was no Dialer Interface configured on the router.

Yes a cellular interface is treated like an async serial and this should be the reason you can use dialer group on them

Hope to help

Giuseppe

[vv0bbLeS]

Excellent! Thank you both for your quick replies! I understand Dialer Interfaces much better now. Thanks again!