LAN9303MI-AKZE Datasheet, PDF (79/386 Pages) SMSC Corporation – Small Form Factor Three Port 10/100 Managed Ethernet Switch with Dual MII/RMII/Turbo MII

Small Form Factor Three Port 10/100 Managed Ethernet Switch with Dual MII/RMII/Turbo MII
Datasheet
6.4.3
ports and the VLAN broadcast domain containment resulted in zero valid destination ports, the
packet is filtered.
Note:
For the last three cases, if the VID is not in the VLAN table, 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).
Transmit Priority Queue Selection
The transmit priority queue may be selected from five options. As shown in Figure 6.4, the priority may
be based on:
„ the static value for the destination address in the ALR table
„ the precedence bits in the IPv4 TOS octet
„ the DIFFSERV mapping table indexed by the IPv4 TOS octet or the IPv6 Traffic Class octet
„ the VLAN tag priority field using the per port Priority Regeneration table
„ the port default
All options are sent through the Traffic Class table which maps the selected priority to one of the four
output queues.
Packet is from Host
Packet is Tagged
Packet is IPv4
Packet is IP
VL Higher Priority
Use Precedence
Use IP
Use Tag
IPv4(TOS)
6b _programmable
3b
IPv6(TC)
DiffServ table
3b
IPv4 Precedence
2b ^programmable
Source Port
port default
table
3b
VLAN Priority
ALR Priority
programmable
Priority
Regeneration
table
per port
3b
priority
3b _calculation
static DA
override
3b
DA Highest Priority
ALR Priority Enable Bit
programmable
Traffic Class
table
2b
priority queue
Figure 6.4 Switch Engine Transmit Queue Selection
SMSC LAN9303M/LAN9303Mi
79
DATASHEET
Revision 1.5 (07-08-11)