Cisco Support Community
Community Member

805 router, serial interfaces in general

I'm sort of new into broadband and I need some explanations. Please, can someone tell me what kind of modem can be connected on a 805 serial interface? For instance, if I have a multi-rate DSL modem, can I use that? 805 has 512k interface...

Another thing. What can be used on serial WIC-T cards? It goes up to 2M sync, I know, but can I connect any HDSL modem to it (are there any restrictions)? There are so many xDSL technologies...

Finally, this thing is really confusing to me. Let's use Zyxel U-336S as an example. It has these basic characteristics:

1) High speed V.34bis to 33.6Kbps

2) Asyn/Syn comunication

3) Serial DTE speed up to 460.8Kbps

4) Dial-up and leased line operation

So, it's a standard analog modem, but with a capability to work on leased lines. But, I don't understand the thing under 3). Does that mean it can go beyond 33.6Kbps with a sync mode, or the speed mentioned is the speed between THIS interface and local router? Can I connect that modem to 805, on a serial interface?

Thanks in advance!

Cisco Employee

Re: 805 router, serial interfaces in general

Serial interface on a 805 router is only a sync interface. Its not a sync/Async interface so you can't connect Analog modem (async) there. Also the DSL modem will not work either. Because dsl modem generally have ethernet port to connec to network side.

For WIC-1T cards and it capabilities/features, pl. visit following url

Now # 3 for Zyxel U-336S mentions the speed between DTE and DCE. So DTE in this case will be a router and DCE is a modem. So that speed is between modem and a router. I don't think that you can connect that modem with 805's serail interface.

Community Member

Re: 805 router, serial interfaces in general

OK, but what about MSDSL modems which have multi-rate capability, and a serial interface? For instance, there is a Schmid modem called Watson 4 (fixed rate modem) that can go to WIC-T cards, and there is Watson 5 that has E1 serial interface (and multi-rate capability) as well as ethernet.

About Zyxel - it says it can work in sync mode (but only up to 33.6k, I understand now). Why do you think it can't work with 805 serial interface?


Cisco Employee

Re: 805 router, serial interfaces in general

I have overlooked one data about 805. Serial interface ONLY on 805 is actually Sync/Async interface so it will support Analog modem connection with it. Visit following url for the capabilitiy of serail interface for 805

Now to support async connection usinf analog modem on serial interface, you need to configure that serial interace (which is sync. by default) to behave as async interface using command "physical layer async" under that.

Here is the url which will help you configure 805 using that serial interface for Sync or Async communication

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