lan9303 Standard Microsystems Corp., lan9303 Datasheet - Page 74

• Manufacturer Part Number: lan9303
• Description: Small Form Factor Three Port 10/100 Managed Ethernet Switch With Single Mii/rmii/turbo Mii
• Manufacturer: Standard Microsystems Corp.

Revision 1.3 (08-27-09)
6.4.4
6.4.5
11 - Disabled
Port State
Member
Port 2
VLAN Support
The Switch Engine supports 16 active VLANs out of a possible 4096. The VLAN table contains the 16
active VLAN entries, each consisting of the VID, the port membership, and un-tagging instructions.
On ingress, if a packet has a VLAN tag containing a valid VID (not 000h or FFFh), the VID table is
searched. If the VID is found, the VLAN is considered active and the membership and un-tag
instruction is used. If the VID is not found, the VLAN is considered foreign and the membership result
is NULL. A NULL membership will result in the packet being filtered if Enable Membership Checking
is set. A NULL membership will also result in the packet being filtered if the destination address is not
found in the ALR table (since the packet would have no destinations).
On ingress, if a packet does not have a VLAN tag or if the VLAN tag contains VID with a value of 0
(priority tag), the packet is assigned a VLAN based on the Port Default VID (PVID) and Priority. The
PVID is then used to access the above VLAN table. The usage of the PVID can be forced by setting
the
The VLAN membership of the packet is used for ingress and egress checking and for VLAN broadcast
domain containment. The un-tag instructions are used at egress on ports defined as hybrid ports.
Refer to
register descriptions.
Spanning Tree Support
Hardware support for the Spanning Tree Protocol (STP) and the Rapid Spanning Tree Protocol (RSTP)
includes a per port state register as well as the override bit in the MAC Address Table entries
6.4.1.5, on page
The
modes as shown in
forwarding. Port 0, which is connected to the host CPU, should normally be left in forwarding mode.
17
802.1Q VLAN Disable
Switch Engine Port State Register (SWE_PORT_STATE)
Received packets on the port are
always discarded.
Transmissions to the port are always
blocked.
Learning on the port is disabled.
Section 13.4.3.8, on page 280
Un-tag
Port 2
16
68) and the host CPU port special tagging
Hardware Action
Member
Port 1
15
Table
Figure 6.6 VLAN Table Entry Structure
bit, in effect creating port based VLANs.
Table 6.2 Spanning Tree States
6.2. Normally only Port 1 and Port 2 are placed into modes other than
Small Form Factor Three Port 10/100 Managed Ethernet Switch with Single MII/RMII/Turbo MII
Un-tag
Port 1
14
DATASHEET
Member
through
13
MII
74
The host CPU may attempt to send packets to the
port in this state, but they will not be transmitted.
Section 13.4.3.11, on page 284
Un-tag
12
MII
11
(Section 6.4.10, on page
is used to place a port into one of the
Software Action
VID
...
SMSC LAN9303/LAN9303i
for detailed VLAN
80).
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Datasheet
(Section