Ethernet Subsystem Registers
14.5.1.13 PORTCTL4 Register (offset = 50h) [reset = 0h]
PORTCTL4 is shown in
and described in
ADDRESS LOOKUP ENGINE PORT 4 CONTROL REGISTER
Figure 14-27. PORTCTL4 Register
31
30
29
28
27
26
25
24
BCAST_LIMIT
R/W-0
23
22
21
20
19
18
17
16
MCAST_LIMIT
R/W-0
15
14
13
12
11
10
9
8
Reserved
7
6
5
4
3
2
1
0
Reserved
NO_SA_UPDATE
NO_LEARN
VID_INGRESS_CHE
DROP_UNTAGGED
PORT_STATE
CK
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; W1toCl = Write 1 to clear bit; -n = value after reset
Table 14-37. PORTCTL4 Register Field Descriptions
Bit
Field
Type
Reset
Description
31-24
BCAST_LIMIT
R/W-0
0
Broadcast Packet Rate Limit - Each prescale pulse loads this field
into the port broadcast rate limit counter.
The port counters are decremented with each packet received or
transmitted depending on whether the mode is transmit or receive.
If the counters decrement to zero, then further packets are rate
limited until the next prescale pulse.
Broadcast rate limiting is enabled by a non-zero value in this field
23-16
MCAST_LIMIT
R/W-0
0
Multicast Packet Rate Limit - Each prescale pulse loads this field into
the port multicast rate limit counter.
The port counters are decremented with each packet received or
transmitted depending on whether the mode is transmit or receive.
If the counters decrement to zero, then further packets are rate
limited until the next prescale pulse.
Multicast rate limiting is enabled by a non-zero value in this field.
5
NO_SA_UPDATE
R/W-0
0
No Souce Address Update - When set the port is disabled from
updating the source port number in an ALE table entry.
4
NO_LEARN
R/W-0
0
No Learn Mode - When set the port is disabled from learning an
address.
3
VID_INGRESS_CHECK
R/W-0
0
VLAN ID Ingress Check - If VLAN not found then drop the packet.
Packets with an unknown (default) VLAN will be dropped.
2
DROP_UNTAGGED
R/W-0
0
Drop Untagged Packets - Drop non-VLAN tagged ingress packets.
1-0
PORT_STATE
R/W-0
0
Port State
0 - Disabled
1 - Blocked
2 - Learn
3 - Forward
1254
Ethernet Subsystem
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated