Multiple Dslams Connected To A Pppoe Access Concentrator Example; Figure 39: Single Dslam Connected To A Pppoe Access Concentrator - Juniper JUNOSE SOFTWARE 11.2.X - LINK LAYER CONFIGURATION GUIDE 7-7-2010 Configuration Manual

ATM
DSLAM

Multiple DSLAMs Connected to a PPPoE Access Concentrator Example

Copyright © 2010, Juniper Networks, Inc.

Figure 39: Single DSLAM Connected to a PPPoE Access Concentrator

Fast Ethernet or
Gigabit Ethernet
Layer 2 switch
In such a case, the PPPoE access concentrator uses the maximum number of
subinterfaces configured on a PPPoE interface using the pppoe sessions command to
limit the maximum number of IWF PPPoE sessions. The B-RAS tracks the IWF flag in a
PPPoE PADR packet it receives from the access concentrator, which the PPPoE client
forwarded to the access concentrator during the discovery stage. The presence of the
IWF tag causes the PPPoE access concentrator to accept duplicate PPPoE sessions with
the same MAC address of the DSLAM are permitted by default. The suboption for the
IWF-Session DSL Forum VSA (26-254) contains the field code of 0xFE in PADR packet
and its length field is set to 0x00.
Consider another scenario in which the access node assigns the same S-VLAN ID to a
group of ports. Figure 40 on page 394 shows a sample configuration scenario in which
multiple DSLAMs are connected to a single PPPoE access concentrator. This configuration
pattern is denoted as N:1 VLAN to indicate many-to-one mapping between ports and
VLAN. Sample criteria for grouping multiple ports with the same S-VLAN ID comprise
the same originating virtual path, same service, or same destination service provider. In
this topology, multiple DSLAMs, which aggregate sessions from multiple PPPoE clients,
are connected to one access concentrator.
Chapter 12: Configuring Point-to-Point Protocol over Ethernet
Layer 2 switch
Gigabit Ethernet
Layer 3 switch
Layer 2 switch
B-RAS
393