Enterasys Networks Security Router X-PeditionTM - Manual (Page 318)

Features
13-6 Configuring ADSL
ADSL on the Motherboard
Two versions of ADSL are provided by the XSR Series 1200 routers:
• Annex A over POTS on the XSR-1220
• Annex B over ISDN on the XSR-1235
DSP Firmware
Digital Signal Processing (DSP) firmware, which the XSR’s onboard ADSL modem uses to
communicate with your provider’s Digital Subscriber Line Access Multiplexer (DSLAM), is stored
in the
adsl.fls file on a CompactFlash card shipped with the ADSL NIM on XSR 1800 and 3000
Series routers (it is embedded on the motherboard on XSR Series 1200 routers). When inserted into
the Compact Flash slot - upon first configuring an ATM interface - the XSR’s ADSL driver copies
adsl.fls into host memory where it will remain available for use on demand. Be aware that if all
ATM interfaces are deleted, adsl.fls must be recopied.
Several CMV commands are provided to “train” the DSP if necessary although it is recommended
they be used by Enterasys field personnel only. The
cmv append command adds variables to the
DSP training list and the cmv clear command removes all of them. Also, cmv cr and cmv cw
read and write variables to the DSP, respectively, cmv delete removes them individually, cmv
print outputs them to the console, and cmv save copies them to a file.
ADSL Data Framing
The XSR supports the ATM Frame UNI (FUNI) mode of data framing on an ADSL line, as defined
by ATM Forum document TR-003.
ATM Frame UNI is a derivative of ATM Data Exchange Interface. Framing is a member of the
HDLC family of data link protocols and, in the XSR, uses the same number of header bytes. It uses
standard HDLC start and stop flag bytes to guarantee flag recognition and bit-stuffing to achieve
data transparency. The ATM FUNI frame header contains address and control fields. The address
field encodes the Service Data Unit's (SDU) virtual connection VPI and VCI.
ATM Support
Virtual Circuits
ADSL supports up to 30 ATM Permanent Virtual Circuits (PVCs) over one virtual circuit number.
PVCs are configured with the
pvc vpi/vci command.
According to DSL Forum document TR-008, the ADSL interface, by default, provisions a single
permanent virtual circuit for data traffic as follows:
• VPI = 1
• VCI = 32
You may configure a different virtual circuit for data traffic.
A second circuit is reserved as the Vendor Specific Channel, as follows:
• VPI = 1
• VCI = 33