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New Member

2503 to multiple ISDN destinations

I have found a 2503 in the back of a cupboard and want to use it to enable systems on a LAN to connect to remote LANs using Basic Rate ISDN.

Q1: Am I right in assuming that I can set up as many routes as I want? (At least the two I need anyway.)

Q2: Can the two channels operate independantly? In other words can a system talk to LAN1 whie another talks to LAN2? If so, can I configure the router so that if only one call is in progress then the second channel can be bundled (to double the throughput) but, if a second call is required then the second channel is released for that call?


New Member

Re: 2503 to multiple ISDN destinations

The cisco 2503 has 1 BRI interface.

The Basic Rate Interface consists of two 64 Kbps B-channels and one 16 Kbps D-channel. Thus, a Basic Rate Interface user can have up to 128 Kbps service.

As the D-channel is commun to both B-channels then you can not dial 2 diffrenet destination with 1 BRI interfce at the same time





Re: 2503 to multiple ISDN destinations

Q1: Yes you can. You define "interesting" traffic with ACLs, which causes the router to dial the number you associate with the traffic.

Q2: Yes you can (to both parts) Each Bearer (B)channel can be defined as an individual dial / circuit-switched path. You also have the option of setting traffic thresholds (high/low) to trigger the addition of a second 'B' (which will be joined with the first, usually with MLPPP) to expand your bandwidth.

At the low threshold, the second channel can be triggered to drop.

It's been a while so, off the top of my head, I don't remember if you could assign a priority to the second channel such that if it was needed for a second call, it can be dropped from a MLPPP group for use as a second channel.

I know that on the old 804, if you had one channel assigned as voice/data, an incoming call would cause the channel to drop it's data role, take the voice call, then resume the data role (if necessary, according to the thresholds).

Good Luck


New Member

Re: 2503 to multiple ISDN destinations

if wanna create 2 destination from 1 BRI interface,

you can create virtual Dialer (eg dialer0,dialer1) to separate LAN1 and LAN2.

ken G

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