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Watson 5 Ethernet
Operating Manual
W5-Ethernet-Manual.doc
Version 2.0-01
3-10 Revision: 2006-04-27
3.2 Ethernet (plugin modem)
3.2.1 Ethernet over DSL
Ethernet packets are mapped on the DSL frame using the packet mode TPS-TC layer of ETSI
TS 101 524. The modems use bit stuffing to improve efficiency.
The Ethernet MAC-frames are reformatted before being transmitted over the DSL link:
! Preamble (PRE), Start-of-Frame delimiter (SFD) and PAD fields are stripped off
! The Ethernet CRC-32 is replaced by a CRC-16 calculated over all fields of the MAC frame
PRE, SFD, an eventual PAD and the CRC-32 are reconstructed by the receiving modem before
transmitting the MAC frame over its Ethernet interface.
DA SA
TCI ML/TL/T
DATA
Transmitted on DSL
stripped off before transmission over DSL
PRE Preamble
SFD Start-of-frame Delimiter
DA Destination address
SA Source address
L/T Length or type indicator = 802.1 QTagType
TCI Tag control information
ML/T MAC client length/type
DATA MAC client data
PAD Padding bytes
CRC Cyclic redundancy check sequence
generated before transmission over DSL
CRC-160x7E 0x7E
HDLC Framing (Flag character)
DA SA TCI
ML/T
L/T
DATA
MAC frame format with
IEEE 802.1p/q VLAN tags
CRC-32SFDPRE PAD
Figure 3-3: Ethernet over DSL
3.2.2 Ethernet Bridging
The Watson 5 Ethernet plugin card has a built-in Ethernet bridge that connects Ethernet ports, DSL
ports and the plugin controller:
Ethernet
Bridge
DSL
Processor
Controller
ETH1
ETH2
ETH3
ETH4
Q
DSL1
DSL2
DSL3
DSL4
a
b
c
d
MGMT3
MGMT1
MGMT2
Backplane of
Subrack SZ.379
DSL Wire pairs
Ethernet User
Interfaces
Management
Ethernet Interface
Figure 3-4: Watson 5 Ethernet plugin Block diagram
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