
MVTX2803
Data Sheet
43
Zarlink Semiconductor Inc.
10.6.3 FCR – Flooding Control Register
I
2
C Address: h040; Serial Interface Address:h502
Accessed by serial interface and I
2
C (R/W)
10.6.4 AVPML – VLAN Priority Map
I
2
C Address: h041; Serial Interface Address:h503
Accessed by serial interface and I
2
C (R/W)
Registers AVPML, AVPMM, and AVPMH allow the eight VLAN priorities to map into eight internal level transmit
priorities. Under the internal transmit priority, ìseven is the highest priority where as ìzero is the lowest. This
feature allows the user the flexibility of redefining the VLAN priority field. For example, programming a value of
7 into bit 2:0 of the AVPML register would map packet VLAN priority ) into internal transmit priority 7. The new
priority is used only inside the 2804. When the packet goes out it carries the original priority.
Bit [5]:
Reserved
Bit [6]:
Select TOS bits for Priority
(Default 0)
0 – Use TOS [4:2] bits to map the transmit priority
1 – Use TOS [5:3] bits to map the transmit priority
Bit [7]:
select TOS bits for Drop
(Default 0)
0 – Use TOS [4:2] bits to map the drop priority
1 – Use TOS [5:3] bits to map the drop priority
7
6
4
3
0
Tos
TimeBase
U2MR
Bit [3:0]:
U2MR: Unicast to Multicast Rate. Units in terms of time base defined in bits [6:4]. This is used to limit
the amount of flooding traffic. The value in U2MR specifies how many packets are allowed to flood
within the time specified by bit [6:4]. To disable this function, program U2MR to 0. (
Default = 4’h8
)
Bit [6:4]:
TimeBase
: (Default = 000)
000 = 10us
001 = 20us
010 = 40us
011 = 80us
100 = 160us
101 = 320us
110 = 640us
111 = 10us, same as 000.
Bit [7]:
Select VLAN tag or TOS field (IP packets) to be preferentially picked to map transmit priority and drop
priority (
Default = 0
).
0 – Select VLAN tag priority field over TOS field
1 – Select TOS field over VLAN tag priority field
7
6
5
3
2
0
VP2
VP1
VP0