Digital Subscriber Line Access Multiplexer (DSLAM) Example Design

Digital Subscriber Line Access Multiplexer (DSLAM) Example Design
• Network model (IP Longest Prefix Match (LPM) or IP 5-Tuple
• Buffer index which indicates where to store incoming packet segments
The routing table is used to determine the IP destination of incoming packets and to what format
they should be converted. This table is accessed by one of two methods as determined from the
network model in the connection table:
• IP Longest Prefix Match (LPM)
• IP 5-Tuple
Each entry in the routing table contains the following:
• Destination IP Address
• Netmask
• Gateway
• Physical Outport Port Number
• VP
• VC
• LLC/SNAP Header
Table 1. L3 Routing Table - IP Route Example
4.3.1 Rate Manager
The Rate Manager creates both the VC and Port table. It allows easy customization of the entries
and is called from the initialization script TM41.ind.
4.3.1.1 Port Table Entry
//////////////////////////////////////////////////////////////////////////////
// Port table entry
struct Unshaped_VC_{
UINT unshaped_unused_0: 8;// For alignment
UINT WRR_count: 8; // WRR weight associated with unshaped 0-15 VC (cells)
UINT vc_index: 16;//Base address of queue associated with an unshaped 0-15
VC
};
typedef struct Unshaped_VC_ Unshaped_VC;
// 32 lw per entry * 256 ports * 4 = 32Kbytes
struct Port_Entry_{
// LongWord - 0
UINT entry_valid: 1;// Message queue base address
UINT port_unused_0: 9;// For alignment
UINT current_unshaped_queue: 5;// Queue # being processed (0-15)
UINT q_with_pkts_vector: 17;// Indicator for 16 VC queues and 1
First_Chance_Q
// LongWord - 1
30 Application Note