Determining Pause Packets - 3.3 English

40G/50G High Speed Ethernet Subsystem v3.3 Product Guide (PG211)

Document ID
PG211
Release Date
2023-11-01
Version
3.3 English

There are three steps in determining pause packets:

  1. Checks are performed to see if a packet is a global or a priority control packet.
    Note: Packets that pass step 1 are forwarded to you only if ctl_rx_forward_control is set to 1.
  2. If step 1 passes, the packet is checked to determine if it is a global pause packet.
  3. If step 2 fails, the packet is checked to determine if it is a priority pause packet.

For step 1, the following pseudo code shows the checking function:

assign da_match_gcp = (!ctl_rx_check_mcast_gcp && !ctl_rx_check_ucast_gcp) || ((DA
== ctl_rx_pause_da_ucast) && ctl_rx_check_ucast_gcp) || ((DA == 48'h0180c2000001) &&
ctl_rx_check_mcast_gcp);

assign sa_match_gcp = !ctl_rx_check_sa_gcp || (SA == ctl_rx_pause_sa);

assign etype_match_gcp = !ctl_rx_check_etype_gcp || (ETYPE == ctl_rx_etype_gcp);
assign opcode_match_gcp = !ctl_rx_check_opcode_gcp || ((OPCODE >=
ctl_rx_opcode_min_gcp) && (OPCODE <= ctl_rx_opcode_max_gcp));

assign global_control_packet = da_match_gcp && sa_match_gcp && etype_match_gcp &&
opcode_match_gcp && ctl_rx_enable_gcp;

assign da_match_pcp = (!ctl_rx_check_mcast_pcp && !ctl_rx_check_ucast_pcp) || ((DA
== ctl_rx_pause_da_ucast) && ctl_rx_check_ucast_pcp) || ((DA ==
ctl_rx_pause_da_mcast) && ctl_rx_check_mcast_pcp);

assign sa_match_pcp = !ctl_rx_check_sa_pcp || (SA == ctl_rx_pause_sa);

assign etype_match_pcp = !ctl_rx_check_etype_pcp || (ETYPE == ctl_rx_etype_pcp);

assign opcode_match_pcp = !ctl_rx_check_opcode_pcp || ((OPCODE >=
ctl_rx_opcode_min_pcp) && (OPCODE <= ctl_rx_opcode_max_pcp));

assign priority_control_packet = da_match_pcp && sa_match_pcp && etype_match_pcp &&
opcode_match_pcp && ctl_rx_enable_pcp;

assign control_packet = global_control_packet || priority_control_packet;

Where DA is the destination address, SA is the source address, OPCODE is the opcode, and ETYPE is the ethertype/length field that are extracted from the incoming packet.

For step 2, the following pseudo code shows the checking function:
assign da_match_gpp = (!ctl_rx_check_mcast_gpp && !ctl_rx_check_ucast_gpp) || ((DA
== ctl_rx_pause_da_ucast) && ctl_rx_check_ucast_gpp) || ((DA == 48'h0180c2000001) &&
ctl_rx_check_mcast_gpp);

assign sa_match_gpp = !ctl_rx_check_sa_gpp || (SA == ctl_rx_pause_sa);
assign etype_match_gpp = !ctl_rx_check_etype_gpp || (ETYPE == ctl_rx_etype_gpp);

assign opcode_match_gpp = !ctl_rx_check_opcode_gpp || (OPCODE == ctl_rx_opcode_gpp);

assign global_pause_packet = da_match_gpp && sa_match_gpp && etype_match_gpp &&
opcode_match_gpp && ctl_rx_enable_gpp;

Where DA is the destination address, SA is the source address, OPCODE is the opcode, and ETYPE is the ethertype/length field that are extracted from the incoming packet.

For step 3, the following pseudo code shows the checking function:

assign da_match_ppp = (!ctl_rx_check_mcast_ppp && !ctl_rx_check_ucast_ppp) && ((DA
== ctl_rx_pause_da_ucast) && ctl_rx_check_ucast_ppp) || ((DA ==
ctl_rx_pause_da_mcast) && ctl_rx_check_mcast_ppp);

assign sa_match_ppp = !ctl_rx_check_sa_ppp || (SA == ctl_rx_pause_sa);
assign etype_match_ppp = !ctl_rx_check_etype_ppp || (ETYPE == ctl_rx_etype_ppp);

assign opcode_match_ppp = !ctl_rx_check_opcode_ppp || (OPCODE == ctl_rx_opcode_ppp);
assign priority_pause_packet = da_match_ppp && sa_match_ppp && etype_match_ppp &&
opcode_match_ppp && ctl_rx_enable_ppp;

Where DA is the destination address, SA is the source address, OPCODE is the opcode, and ETYPE is the ethertype/length field that are extracted from the incoming packet.