L-ET4148-50C-DB LSI, L-ET4148-50C-DB Datasheet - Page 271

• Manufacturer Part Number: L-ET4148-50C-DB
• Manufacturer: LSI

Specifications of L-ET4148-50C-DB

• Lead Free Status / RoHS Status: Supplier Unconfirmed

Preliminary Data Sheet
April 2006
Agere Systems Inc.
Appendix B: Configuration
Ethernet Interfaces
VLANs
Every receive packet is associated with one VLAN or another by the ET4148-50 during reception. There are sev-
eral methods by which such a VLAN association may be made.
1.Directly. The VLAN tag of a received packet is mapped to a VLAN index.
2. Port/protocol. Untagged packets are mapped to a VLAN index based on a per-port protocol table.
3. Port only. Untagged packets adopt the receive port’s default VLAN ID.
For the purposes of restricting the forwarding of packets within VLANs, a series of VLAN masks are used.
Direct Mapping. Although the IEEE 802.1q standard allows up to 4,094 VLAN IDs, the ET4148-50 supports up to
256 active VLANs. The Vlan_Index_Table_{0..6} registers are used to map the 12-bit VLAN tag from a receive
packet to the 8-bit VLAN identifier that is used internally within the ET4148-50. This table is addressed directly by
the receive packet’s 12-bit VLAN tag. A vlan_index_valid flag in each table entry identifies those entries that
are indeed valid. For valid entries, the vlan_index[7:0] value from the same record is used as the receive
packet’s VLAN index.
If the receive packet’s 12-bit VLAN ID maps to an invalid entry in Vlan_Index_Table_{0..6}, then the packet is
either discarded or its VLAN index is chosen by one of the alternate methods listed above and described in more
detail below. The invalid_vlan_id_discard_en bits in the Port_Mode_{0..6} registers are used to set this
preference on a port-by-port basis.
Note: Revisions B1 and C of the ET4148-50 allow up to 4,095 VLAN IDs. VLAN ID 0xFFF is included for non-
Port/Protocol Mapping. For each receive port, as many as eight Ethertype values may be mapped to VLAN index
values. The following ordered list of Ethertypes is used.
Table 381. Ethertype Index Values
The three user type values are established via the User_Type_{0..6} registers. Typically, all seven instances of
this register are programmed the same way, but it is not necessary to do so.
The Ethertype index is used to select one of the eight VLAN index values from the
Vlan_Port_Protocol_Table_{0..6} registers. There is an eight-entry table for each receive port.
Valid entries are identified by an asserted entry_valid bit. If the combination of receive port number and Ether-
type index points to a valid entry, then the associated vlan_index[7:0] value is assigned to the receive packet.
Otherwise, the port-only VLAN assignment method (described below) is used.
IPv4
IPv6
ARP
RARP
User Type 0
User Type 1
User Type 2
Unknown
Ethertype
standard use.
(continued)
Ethertype Index
Single-Chip 48 x 1 Gbit/s + 2 x 10 Gbits/s Layer 2+ Ethernet Switch
0
1
2
3
4
5
6
7
(continued)
Agere Systems - Proprietary
ET4148-50
271