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IP SWITCHES
1. Receive INFLOWS DATAIN
IP SWITCHES…
1. Receive INFLOWS DATAIN
2. BUFFER & Route
IP SWITCHES
1. Receive INFLOWS
2. BUFFER & Route
3. Transmit OUTFLOWS
DATA IN
DATA OUT
IP SWITCHES
1. Receive INFLOWS DATAIN
2. BUFFER & Route
3. Transmit OUTFLOWS DATAOUT
TRAFFIC SHAPING AFFECTS HOW MUCH BUFFER AN IP SWITCH NEEDS
THE PRINCIPLE IS ANALOGOUS TO WATER FLOWING IN & OUT OF A BUCKET
DATA IN
DATA OUT
ANALOGY
WATER IN
WATER OUT
THE PRINCIPLE IS ANALOGOUS TO WATER FLOWING IN & OUT OF A BUCKET
DATA IN
DATA OUT
WATER IN
WATER OUT
1. Both have INFLOWS
THE PRINCIPLE IS ANALOGOUS TO WATER FLOWING IN & OUT OF A BUCKET
DATA IN
DATA OUT
WATER IN
WATER OUT
1. Both have INFLOWS
2. Both BUFFER
THE PRINCIPLE IS ANALOGOUS TO WATER FLOWING IN & OUT OF A BUCKET
DATA IN
DATA OUT
WATER IN
WATER OUT
1. Both have INFLOWS
2. Both BUFFER
3. Both have OUTFLOWS
IN THIS ANALOGY…
UNIFORM PACKET SPACING(NARROW TRAFFIC SHAPE)
UNIFORM WATER FLOW
EQUATES TO
DATA IN
PACKETS
Δt1Δt2Δt3Δt4
Δt1≈ Δt2 ≈ Δt3 ≈ Δt4
UNIFORM WATER FLOWIF THE WATER FLOW IS UNIFORM
WITH THE WATER/BUCKET ANALOGY…
UNIFORM WATER FLOWIF THE WATER FLOW IS UNIFORM
AMOUNT OF WATERENTERING
AND
=AMOUNT OF WATEREXITING
WITH THE WATER/BUCKET ANALOGY…
UNIFORM WATER FLOWIF THE WATER FLOW IS UNIFORM
AMOUNT OF WATERENTERING
AND
=AMOUNT OF WATEREXITING
THE BUCKET NEVER OVERFLOWS
WITH THE WATER/BUCKET ANALOGY…
IF PACKET SPACING IS UNIFORMDATA IN
DATA OUT
(TRAFFIC PROFILE IS VERY NARROW)
WITH AN IP SWITCH…
IF PACKET SPACING IS UNIFORM
AMOUNT OF DATAENTERING
AND
=AMOUNT OF DATAEXITING
DATA IN
DATA OUT
(TRAFFIC PROFILE IS VERY NARROW)
WITH AN IP SWITCH…
IF PACKET SPACING IS UNIFORM
AMOUNT OF DATAENTERING
AND
=AMOUNT OF DATAEXITING
SWITCH MEMORY NEVER OVERFLOWS
DATA IN
DATA OUT
(TRAFFIC PROFILE IS VERY NARROW)
WITH AN IP SWITCH…
NON-UNIFORM WATER FLOWIF THE WATER FLOW IS “BURSTY”
WITH THE WATER/BUCKET ANALOGY…
NON-UNIFORM WATER FLOWIF THE WATER FLOW IS “BURSTY”
WITH THE WATER/BUCKET ANALOGY…
AVERAGEAMOUNT OF WATERENTERING
AND
=AVERAGEAMOUNT OF WATEREXITING
NON-UNIFORM WATER FLOWIF THE WATER FLOW IS “BURSTY”
WITH THE WATER/BUCKET ANALOGY…
AVERAGEAMOUNT OF WATERENTERING
AND
=AVERAGEAMOUNT OF WATEREXITING
THEN WATER LEVEL VARIES…
…AND IF THE BUCKETISN’T BIG ENOUGH…
NON-UNIFORM WATER FLOWIF THE WATER FLOW IS “BURSTY”
WITH THE WATER/BUCKET ANALOGY…
AVERAGEAMOUNT OF WATERENTERING
AND
=AVERAGEAMOUNT OF WATEREXITING
THE BUCKET OVERFLOWS
THEN WATER LEVEL VARIES…
…AND IF THE BUCKETISN’T BIG ENOUGH…
IF PACKET FLOW IS “BURSTY”
WITH AN IP SWITCH…
(TRAFFIC PROFILE IS WIDE)DATA IN
DATA OUT
IF PACKET FLOW IS “BURSTY”
AVERAGEAMOUNT OF DATAENTERING
AND
=AVERAGEAMOUNT OF DATAEXITING
WITH AN IP SWITCH…
(TRAFFIC PROFILE IS WIDE)DATA IN
DATA OUT
IF PACKET FLOW IS “BURSTY”
AVERAGEAMOUNT OF DATAENTERING
AND
=AVERAGEAMOUNT OF DATAEXITING
WITH AN IP SWITCH…
THEN BUFFER LEVEL VARIES…
…AND IF THE SWITCH BUFFERISN’T BIG ENOUGH…
(TRAFFIC PROFILE IS WIDE)DATA IN
DATA OUT
IF PACKET FLOW IS “BURSTY”
AVERAGEAMOUNT OF DATAENTERING
AND
=AVERAGEAMOUNT OF DATAEXITING
THE BUFFER OVERFLOWS
WITH AN IP SWITCH…
THEN BUFFER LEVEL VARIES…
…AND IF THE SWITCH BUFFERISN’T BIG ENOUGH…
(TRAFFIC PROFILE IS WIDE)DATA IN
DATA OUT
DROPPED PACKETS
CONCLUSION
ASNON-UNIFORMWATER FLOWSREQUIREABIGENOUGHBUCKET TOACCOUNTFOR
WATERLEVELVARIATION…
CONCLUSION
ASNON-UNIFORMWATER FLOWSREQUIREABIGENOUGHBUCKET TOACCOUNTFOR
WATERLEVELVARIATION…
DATA IN
DATA OUT
…NON-UNIFORMDATA FLOWS(WIDETRAFFICSHAPES)REQUIREENOUGHIPSWITCH
BUFFERMEMORY TOACCOUNTFORDATALEVELVARIATIONWITHINTHESWITCH
CONCLUSIONDATA IN
DATA OUT
…NON-UNIFORMDATA FLOWS(WIDETRAFFICSHAPES)REQUIREENOUGHIPSWITCH
BUFFERMEMORY TOACCOUNTFORDATALEVELVARIATIONWITHINTHESWITCH
• SUCHDEEPBUFFERMEMORYSWITCHESAREAVAILABLEANDCANBESPECIFIEDWHENUSINGSMPTEST2110-21WIDETRAFFICSHAPING
• USINGSMPTEST2110-21NARROWTRAFFICSHAPINGMINIMIZESSWITCHMEMORYREQUIRED
TAKEAWAYS
