www.ti.com
Functional Description
14.3.2.10.1 Normal Priority Mode
When operating in normal mode, lower priority frames are dropped before higher priority frames. The
intention is to give preference to higher priority frames. Priority 3 is the highest priority and is allowed to fill
the FIFO. Priority 2 will drop packets if the packet is going to take space in the last 2k available. Priority 1
will drop packets if the packet is going to take space in the last 4k available. Priority 0 will drop packets if
the packet is going to take space in the last 6k available. If fewer than 4 priorities are to be implemented
then the priorities should be mapped such that the highest priorities are used.
For example, if two priorities are going to be used then all packets should be mapped to priorities 3 and 2
and priorities 1 and 0 should be unused. Priority escalation may be used in normal priority mode if
desired. Normal priority mode is configured as described below:
• Select normal priority mode by setting tx_in_sel[1:0] = 00 for all ports (default value in
P0/1/2_Tx_In_Ctl)
• Configure priority mapping to use only the highest priorities if less than 4 priorities are used. Refer to
the Packet Priority Handling section of this chapter.
14.3.2.10.2 Dual Mac Mode
When operating in dual mac mode the intention is to transfer packets between ports 0 and 1 and ports 0
and 2, but not between ports 1 and 2. Each CPGMAC_SL appears as a single MAC with no bridging
between MAC’s. Each CPGMAC_SL has at least one unique (not the same) mac address.
Dual mac mode is configured as described below:
• Set the ale_vlan_aware bit in the ALE_Control register. This bit configures the ALE to process in vlan
aware mode.The CPSW_3G vlan aware bit (vlan_aware in CPSW_Control) determines how packets
VLAN’s are processed on CPGMAC_SL egress and does not affect how the ALE processes packets or
the packet destination. The CPSW_3G vlan aware bit may be set or not as required (must be set if
VLAN’s are to exit the switch).
• Configure the Port 1 to Port 0 VLAN
Add a VLAN Table Entry with ports 0 and 1 as members (clear the flood masks).
Add a VLAN/Unicast Address Table Entry with the Port1/0 VLAN and a port number of 0. Packets
received on port 1 with this unicast address will be sent only to port 0 (egress). If multiple mac addresses
are desired for this port then multiple entries of this type may be configured.
• Configure the Port 2 to Port 0 VLAN
Add a VLAN Table Entry with ports 0 and 2 as members (clear the flood masks).
Add a VLAN/Unicast Address Table Entry with the Port2/0 VLAN and a port number of 0. Packets
received on port 2 with this unicast address will be sent only to port 0 (egress). If multiple mac addresses
are desired for this port then multiple entries of this type may be configured.
• Packets from the host (port 0) to ports 1 and 2 should be directed. If directed packets are not desired
then VLAN with addresses can be added for both destination ports.
• Select the dual mac mode on the port 0 FIFO by setting tx_in_sel[1:0] = 01 in P0_Tx_In_Ctl. The
intention of this mode is to allow packets from both ethernet ports to be written into the FIFO without
one port starving the other port.
• The priority levels may be configured such that packets received on port 1 egress on one CPDMA RX
channel while packets received on port 2 egress on a different CPDMA RX channel.
14.3.2.10.3 Rate Limit Mode
Rate-limit mode is intended to allow some CPDMA transmit (switch ingress) channels and some
CPGMAC_SL FIFO priorities (switch egress) to be rate-limited. Non rate-limited traffic (bulk traffic) is
allowed on non rate-limited channels and FIFO priorities. The bulk traffic does not impact the rate-limited
traffic. Rate-limited traffic must be configured to be sent to rate-limited queues (via packet priority
handling).
1205
SPRUH73H–October 2011–Revised April 2013 Ethernet Subsystem
Submit Documentation Feedback
Copyright © 2011–2013, Texas Instruments Incorporated
To Next Page
Loading...
Need help?
General
