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Compact mDSL Modem

Configuration

There are two modes of operation for the Compact mDSL Modem:
Plug-n-Play and self configuration. Both are described below.

Plug-n-Play

The Plug-and-Play feature allows ISPs, carriers and PTTs to

quickly upgrade the link speed for a customer without requiring a truck
roll to configure the Customer Premise (CP) Compact mDSL Modem.
This feature also allows service providers to set up all of the configura-
tions at the Central Office (on the rack cards) before installing the
stand alone units, saving time spent configuring or re-configuring DIP
switches.

The Plug-n-Play feature allows the user to configure the DTE rate
(bandwidth allocation, see Switches S3-1 through S3-6) of the CP unit
from the rack card at the Central Office (CO). The stand alone unit at
the Customer Premise (CP) site will automatically configure itself to the
DTE rate (Bandwidth Allocation) of the rack card. Other configuration
parameters remain in the default setting.

Follow the instructions below to activate Plug-n-Play between CO

(mDSL Rack Card) and CP (Compact mDSL Modem) units:

Set the mDSL Rack Card (CO) to either Internal or External
clocking mode as defined by the application.

Set the Compact mDSL Modem (CP) to “Plug-and-Play CP”
by setting all S2 and S3 DIP switches in the OFF position as
described in Figure 3, below.

When the CO and CP units connect over DSL, the CP will enter a

predefined default configuration (Receive Recovered Clocking). During
the negotiation process between the units, the CO unit will configure
the DTE rate/line rate on the CP unit as defined by the settings of the
CO unit. When additional bandwidth is required, only the configuration

For example, the customer site is assigned the addresses

192.168.1.0/24 through 192.168.1.1/24. The address
192.168.1.1/24 is also the default gateway for the remote net-
work. The above settings remove any routing/forwarding intel-
ligence from the CPE. The associated Cisco configuration will
set serial interface (s0) to accommodate half bridging for the
above example.

Authentication is optional under PPP. In a point-to-point

leased-line link, incoming customer facilities are usually fixed
in nature, therefore authentication is generally not required. If
the foreign device requires authentication via PAP or CHAP,
the PPP software will respond with default Peer-ID consisting
of the units Ethernet MAC address and a password which
consists of the unit’s Ethernet MAC address.

Some networking systems do not define network numbers

in packets sent out over a network. If a packet does not have
a specific destination network number, a router will assume
that the packet is set up for the local segment and will not for-
ward it to any other sub-network. However, in cases where
two devices need to communicate over the wide-area, bridg-
ing can be used to transport non-routable protocols.

Figure 2 illustrates transparent bridging between two

routers over a serial interface (s0). Bridging will occur
between the two Ethernet Interfaces on Router A (e0 and e1)
and the two Ethernet Interfaces on Router B (e0 and e1).

Black Box

MDU9705A-10BT

Ethernet LAN

PEC Device w/ Serial I/F

Router

Figure 1.

Cisco router with serial interface, configured as PPP Half Bridge.

!
no ip routing
!
interface Ethernet0
ip address 1.1.1.1 255.255.255.0
bridge-group 1
!
interface Serial0
ip address 1.1.1.1 255.255.255.0
encapsulation PPP
bridge-group 1
!
interface Serial1
ip address 2.2.2.2 255.255.255.0
bridge-group 1
!
bridge 1 protocol ieee
!