LAN9303 Datasheet, PDF (80/366 Pages) SMSC Corporation – Small Form Factor Three Port 10/100 Managed Ethernet Switch with Single MII/RMII/Turbo MII

Small Form Factor Three Port 10/100 Managed Ethernet Switch with Single MII/RMII/Turbo MII
Datasheet
Note: Most forwarding rules are skipped when a packet is monitored. However, a packet is still filtered
if:
„ The source port is in the Disabled state
„ The source port is in the Learning or Listening / Blocking state (unless Spanning Tree Port
State Override is in effect.
„ VLAN’s are enabled, the packet is untagged or priority tagged, and the Admit Only VLAN
bit for the ingress port is set.
„ VLAN’s are enabled and the packet is tagged and had a VID equal to FFFh.
„ VLAN’s are enabled, Enabled Membership Checking on Ingress is set, Admit Non Member
is cleared, and the source port is not a member of the incoming VLAN.
6.4.9 Port Mirroring
The device supports port mirroring where packets received or transmitted on a port or ports can also
be copied onto another “sniffer” port.
Port mirroring is configured using the Switch Engine Port Mirroring Register (SWE_PORT_MIRROR).
Multiple mirrored ports can be defined, but only one sniffer port can be defined.
When receive mirroring is enabled, packets that are forwarded from a port designated as a mirrored
port are also transmitted by the sniffer port. For example, Port 2 is setup to be a mirrored port and
Port 0 is setup to be the sniffer port. If a packet is received on Port 2 with a destination of Port 1, it
is forwarded to both Port 1 and Port 0.
When transmit mirroring is enabled, packets that are forwarded to a port designated as a mirrored port
are also transmitted by the sniffer port. For example, Port 2 is setup to be a mirrored port and Port 0
is setup to be the sniffer port. If a packet is received on Port 1 with a destination of Port 2, it is
forwarded to both Port 2 and Port 0.
Note: A packet will never be transmitted out of the receiving port. A receive packet is not normally
mirrored if it is filtered. This can optionally be enabled.
6.4.10 Host CPU Port Special Tagging
The Switch Engine Ingress Port Type Register (SWE_INGRSS_PORT_TYP) and Buffer Manager
Egress Port Type Register (BM_EGRSS_PORT_TYPE) are used to enable a special VLAN tag that is
used by the host CPU. This special tag is used to specify the port(s) where packets from the CPU
should be sent, and to indicate which port received the packet that was forwarded to the CPU.
6.4.10.1
Packets from the Host CPU
The Switch Engine Ingress Port Type Register (SWE_INGRSS_PORT_TYP) configures the switch to
use the special VLAN tag in packets from the host CPU as a destination port indicator. A setting of
11b should be used on the port that is connected to the host CPU (typically Port 0). A setting of 00b
should be used on the normal network ports.
The special VLAN tag is a normal VLAN tag where the VID field is used as the destination port
indicator.
VID bit 3 indicates a request for an ALR lookup.
If VID bit 3 is zero, then bits 0 and 1 specify the destination port (0, 1, 2) or broadcast (3). Bit 4 is
used to specify if the STP port state should be overridden. When set, the packet will be transmitted,
even if the destination port(s) is (are) in the Learning or Listening / Blocking state.
If VID bit 3 is one, then the normal ALR lookup is performed and learning is performed on the source
address (if enabled in the Switch Engine Port Ingress Configuration Register
(SWE_PORT_INGRSS_CFG) and the port state for the CPU port is set to Forwarding or Learning).
The STP port state override is taken from the ALR entry.
Revision 1.3 (08-27-09)
80
DATASHEET
SMSC LAN9303/LAN9303i