Digital Subscriber Line Access Multiplexer (DSLAM) Example Design
Digital Subscriber Line Access Multiplexer (DSLAM) Example Design
Digital Subscriber Line Access Multiplexer (DSLAM) Example Design
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<strong>Digital</strong> <strong>Subscriber</strong> <strong>Line</strong> <strong>Access</strong> <strong>Multiplexer</strong> (<strong>DSLAM</strong>) <strong>Example</strong> <strong>Design</strong><br />
Figure 13 shows how PDUs and flow control packets output from the Receive Processor to the<br />
IXB3208 are formatted. These PDUs and flow control packets are prepended with an inter-IXP<br />
header (containing classification information for traffic management), segmented, and then prepended<br />
with IXB3208 headers. (IXB3208 headers follow a standard format as specified in the<br />
IXB3208 documentation.) The input to the Transmit Processor is the same data with the IXB3208<br />
headers stripped off by the IXB3208.<br />
Figure 13. Receive Processor Output to IXB3208<br />
PDU or<br />
Flow Control<br />
Reassembled/modified PDU<br />
or Flow Control<br />
multiple of 48 bytes<br />
Classification Inter-IXP Header Reassembled/modified PDU<br />
or Flow Control<br />
SAR Sub-Layer<br />
(output from<br />
Processor A)<br />
Intel ®<br />
IXB3208<br />
Header<br />
Payload<br />
64 bytes<br />
Intel<br />
IXB3208<br />
Header<br />
Payload<br />
64 bytes<br />
Intel<br />
IXB3208<br />
Header<br />
Payload<br />
64 bytes<br />
A9556-01<br />
Figure 14 shows the format of the Inter-IXP header, which is used to communicate packet<br />
classification data from the Receive Processor to the Transmit Processor.<br />
Figure 14. Inter-IXP Header Format<br />
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Offset<br />
Last Byte<br />
C A M Type CLP Priority Time Last Quadword in Packet<br />
in Packet<br />
0<br />
Source VC or Vport Destination VC or Multicast Group 1<br />
Legend<br />
C<br />
A<br />
M<br />
CLP<br />
Type<br />
Priority<br />
Time<br />
Last Quadword in<br />
Packet<br />
Last Byte in<br />
Packet<br />
Source VC or<br />
Vport<br />
Destination VC or<br />
Multicast Group<br />
Control Indicator<br />
0 = command packet<br />
1 = data packet<br />
ATM Indicator<br />
0 = unicast packet is not ATM<br />
1 = unicast packet is ATM<br />
Multicast Indicator<br />
0 = unicast packet<br />
1 = multicast packet<br />
Cell Loss Priority Indicator<br />
Connection Type<br />
1 =<br />
UBR<br />
2 =<br />
VBR<br />
4 =<br />
CBR<br />
The UBR Priority<br />
Time IXP1200 A spent on the packet in 1 microsec increments.<br />
The quadword offset from the start of the packet to the last quadword of data for the<br />
packet<br />
The last byte in packet is the number of valid bytes in the last quadword 1.<br />
These appear to be unique numbers per IP address.<br />
Application Note 27
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