How The Ether-1000 Units Maps Ip Frames To Priority Queues; Figure 55: Tos Byte - GE JungleMUX SONET Technical Practice

How the ETHER-1000 units maps IP frames to priority queues?

The unit assigns priorities as follows:
Note that TOS[5:0] denotes the 6 msb of the byte where they reside.
0 0
TOS[5] TOS[5] TOS[4] TOS[3] TOS[2] TOS[1] TOS[0] TOS[4] TOS[3] TOS[2] TOS[1] TOS[0]
Bits 0-2: Precedence Bits 0-2: Precedence
Bit 3: Bit 3:
Bit 4: Bit 4:
Bit 5: Bit 5:
Bits 6-7: Reserved for Future Use Bits 6-7: Reserved for Future Use
If TOS[2:0] = 000, set Priority[2:0] = TOS[5:3] (the "Precedence" field)
Else If TOS[0] = 1, set Priority[2:0] = 6 (if the "Reliability" bit is set)
Else If TOS[1] = 1, set Priority[2:0] = 5 (if the "Throughput" bit is set)
(So TOS[2] = 1),
The above ETHER-1000 unit‟s mapping is a very arbitrary one, based on nothing
more intelligent than an interpretation of the original "Precedence" & TOS
concept.
The mapping is implemented by a 64x3-bit lookup table, so if a more useful
mapping surfaces, this table could easily be changed.
The same table is used for all traffic ingressing the unit. Although a separate
table could be provided for each port for the "WAN" switch queues, this could not
be provided for the Marvell‟s "LAN" switch.
Copyright  GE Multilin Inc. 2010-2012
1 1 2 2 3 3
D D
111 - Network Control 111 - Network Control
110 - Internetwork Control 110 - Internetwork Control
101 - CRITIC/ECP 101 - CRITIC/ECP
100 - Flash Override 100 - Flash Override
011 - Flash 011 - Flash
010 - Immediate 010 - Immediate
001 - Priority 001 - Priority
000 - Routine 000 - Routine
0 = Normal Delay, 0 = Normal Delay,
0 = Normal Throughput, 1 = High Throughput 0 = Normal Throughput, 1 = High Throughput
0 = Normal Reliability, 0 = Normal Reliability,

Figure 55: TOS Byte

set Priority[2:0] = 4 (the "Low Delay" bit is set)
342-86400-498PS
Issue 1.2
April 2012
Page 160
4 4 5 5 6 6
T T R R 0 0
1 = Low Delay 1 = Low Delay
1 = High Reliability 1 = High Reliability
7 7
0 0