DS33X81+ Maxim Integrated Products, DS33X81+ Datasheet - Page 43

• Manufacturer Part Number: DS33X81+
• Description: IC MAPPING ETHERNET 256CSBGA
• Manufacturer: Maxim Integrated Products

Specifications of DS33X81+

• Applications: Data Transport
• Interface: Parallel/Serial
• Voltage - Supply: 1.8V, 2.5V, 3.3V
• Package / Case: 256-CSBGA
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Ethernet frames from both ports can be forwarded by VLAN tag (VID) to one of two shared WAN groups. Within
each shared WAN group, there are two sets of four strict priority queues. The two sets of strict priority queues are
serviced with a round-robin algorithm. Frames are then encapsulated by Encapsulator #1 or #3. Frames received
8.9
The path any given frame takes through the device can be determined by the contents of the frame, the port of
entry, the user configured WAN Connections, and the user configured Forwarding Mode.
8.9.1
The set of rules that determine the route of frames between the Ethernet Interface(s) and WAN data stream(s) is
called the Forwarding Mode. The forwarding mode is selected in the GL.CR1 register. The five Forwarding Modes
are listed below. The connections between the Serial (WAN) Interfaces and the logical WAN data streams
described below are independent of these Forwarding Modes and will be described later. See Table 8-4 for
forwarding modes supported by each device.
Mode 1 - Single Ethernet Port with Priority Forwarding
Mode 2 - Per-Ethernet-Port Forwarding with Priority Scheduling
Mode 3 - Single Ethernet Port with VLAN Forwarding and Priority Scheduling
Mode 4 - Per-Ethernet-Port Forwarding, with VLAN Forwarding and Priority Scheduling within each VLAN group
Mode 5 – Full VLAN Forwarding in both the LAN-to-WAN and WAN-to-LAN directions.
Forwarding Mode 1 is Single Ethernet Port with Priority Forwarding. In this mode, Ethernet frames are segregated
into up to four priority queues and transmitted in separate WAN data streams. One example application is an
Ethernet Switch that forwards its traffic according to each frame’s priority encoding, as in an IP DSLAM or ISAM
that has a WAN connection with a VoIP Gateway on WAN Interface #1, a Video Stream device on WAN Interface
#2, and an internet POP on WAN Interface #3.
Forwarding Mode 2 is Per-Ethernet-Port Forwarding with Priority Scheduling. In this mode, frames from each
Ethernet port are forwarded to their own group of four priority queues, generating two separate WAN data streams
with priority scheduled traffic. One example application is a Leased Line Service for two independent Ethernet
subscribers. Each subscriber pays its own leased line fee and is guaranteed the full bandwidth of the WAN line
from end to end. This is the only mode that supports 1000Mbps Jumbo Frames (must use single Ethernet port
operation).
Forwarding Mode 3 is Single Ethernet Port with VLAN Forwarding and Priority Scheduling. In this mode, Ethernet
frames are forwarded by VLAN tag (VID) into up to four groups of four priority queues (WAN Groups) each. Each
WAN Group forms a separate WAN data stream with priority scheduled traffic. One example application is an
Service Router that is connected to four IP DSLAMs via DS3s. In the LAN-to-WAN direction, VLAN IDs are used to
distinguish the forwarding path while Priority coding is used to schedule the selection of frames within a Queue
Group.
Forwarding Mode 4 is Per-Ethernet-Port Forwarding, with VLAN Forwarding and Priority Scheduling within each
VLAN Group. In this mode, Ethernet frames from each Ethernet port are forwarded separately, by VLAN tag, into
two sets of four priority queues (WAN Groups) each. The two WAN Groups form separate WAN data streams with
priority scheduled traffic. One example application is 2 Leased Lines for 2 independent Ethernet subscribers (one
route might go to Chicago and the other to Santa Clara). VLAN tagging is used to segregate the traffic bound for
each route, and Priority coding can be used to provide prioritized scheduling within a VLAN group.
Forwarding Mode 5 is Full VLAN Forwarding in both the LAN-to-WAN and WAN-to-LAN directions. In this mode,
from the WAN side can be forwarded by VLAN tag to either Ethernet port. The LAN-to-WAN and WAN-to-LAN
mappings are independent and can be configured separately. One example application is Central Office traffic
grooming where the time sensitive voice and video are segregated from a network and combined with other data
streams of similar priority.
Rev: 063008
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Forwarding Modes and WAN Connections
Forwarding Modes
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