CS 6250 EXAM 2 QUESTIONS AND ANSWERS

CS 6250 EXAM 2 QUESTIONS AND
ANSWERS



What8are828reasons8computer8networks8are8complex8and8difficult8to8manage8that8led8to8t
he8development8of8SDN?8-8answer--1.8Diversity8of8network8equipment

2.8Proprietary8technology8required8for8equipment

Why8would8equipment8diversity8cause8complexity8when8managing8a8network?8-
8answer--Different8software8must8be8used8for8different8protocols8(7)



Why8do8proprietary8technologies8cause8complexity8when8managing8networks?8-
8answer--Some8equipment8(router,8switch,8etc.)8run8on8closed/proprietary8software



Configuration8interfaces8vary8as8a8result.

This8causes8issues8for8managing8devices8centrally.8(7)

What8is8the8simple8idea8of8SDN8that8helps8make8networks8more8manageable?8-
8answer--Separate8tasks8into8control8plane8and8data8plane.8(7)



What8are8the838phases8of8history8of8SDN?8-8answer--1.8Active8networks

2.8control8plane8and8data8plane8separation

3.8OpenFlow8API8and8network8operating8systems8(7)

What8led8to8the8growth8of8active8networks,8and8what8is8their8goal?8-8answer--
1.8the8tediousness8of8standardizing8new8protocols

2.8goal8is8to8open8up8network8control8with8an8API8that8exposes8resources8and8supports8*
customization8of8functionalities*8for8subsets8of8packets8passing8through8network8nodes

(7)

Why8do8active8networks8conflict8with8idea8of8E2E?8-8answer--
They8require8customization8at8network8nodes8(not8simplicity8at8network8core)
(7)

,What8were8the8two8types8of8programming8models8in8active8networking?
8How8are8thy8different?8-8answer--1.8Capsule8model

-8carries8in8band8data8packets
-8most8used8in8relation8to8active8networking
-8code8distribution8ACROSS8networks
-8data8plane

2.8Programmable8router/switch8model
-8out8of8band8mechanisms
-8decision-making8a8job8for8the8NETWORK8OPERATOR

-8Difference8is8where8the8code8to8execute8at8the8nodes8was8carried8(7)

What8are848tech8developments8that8encouraged8active8networking?8-8answer--
1.8reduction8in8computation8cost8(more8processing8can8take8place8in8the8network)

2.8advancement8in8programming8languages

3.8advancement8in8rapid8code8compilation8and8formal8methods

4.8funding8agencies8promoted8interoperability8among8projects
-8necessary8because8there8were8no8short-term8use8cases

(7)

What8are848problems8that8encouraged8active8networking?8-8answer--
1.8developing8network8services8took8a8long8time

2.8third8party8interests8to8dynamically8meeting8needs8of8app8and8network8conditions

3.8researches8needed8a8network8for8large-scale8experiments

4.8disadvantage8of8diverse8models8and8vendors8meant8a8desire8for8unified8control8over8
middleboxes8(7)

What8are838contributions8of8SDN?8-8answer--
1.8programmable8functions8in8network8=8lower8barrier8to8innovation

2.8network8virtualization8and8ability8to8demultiplex8based8on8packet8headers

3.8vision8of8unified8architecture8for8middlebox8orchestration

(7)

Which8plane8are8active8networks8associated8with?8-8answer--Data8plane8(7)

,What8plane8do8programmable8functions8in8active8networks8focus8on8increasing8program
mability,8and8why?8-8answer---8Data8plane
-8isolate8experimental8traffic8from8normal8traffic8(7)

What8were8some8downfalls8of8active8networking?8-8answer---8it8was8too8ambitions
-8didn't8emphasize8performance8and8security
-8it8didn't8solve8any8short8term8problems
-8end8users8need8to8be8ale8to8write8in8java8(7)

Did8active8network8do8anything8for8performance?8Security?8-8answer--No8(7)

What8challenge8did8control8and8data8plane8separation8tackle?8-8answer--
Challenging8how8existing8routers8and8switches8tightly8integrated8the8data8and8control8pla
ne8(7)

What8were848tech8developments8that8paved8the8way8for8control8and8data8plane8separatio
n?8-8answer--
1.8packet8forwarding8(data8plane)8was8implemented8in8hardware8(separate8from8control8
plane)

2.8ISPs8couldn't8meet8increasing8demands8for8greater8reliability8and8new8services8b/
c8of8increasing8scope8and8size

3.8servers8have8much8more8memory8and8processing8resources8-
8routing8decisions8could8be8done8on8one8server8for8one8ISP8network



4.8open-
source8routing8lowers8barrier8to8creating8prototypes8of8centralized8routing8controllers

(7)

How8did8higher8link8speeds8in8backbone8networks8encourage8control8and8data8plane8sep
aration?8-8answer--
packet8forwarding8implemented8in8hardware,8separate8from8control8plane8(7)

What828innovations8led8to8the8control8and8data8plane8separation?8-8answer--
1.8open8interface8between8control8and8data8plane

2.8logically8centralized8control8of8network(7)

Was8the8network8centrally8controlled8logically,8physically,8or8both8under8control8and8data
8plane8separation?8-8answer--LOGICALLY8centrally8controlled(7)



What8are838ways8control8plane8and8data8plane8separation8differed8form8active8networks?
8-8answer--1.8Spurred8innovation8for8network8ADMINS8instead8of8users

, 2.8emphasized8programmability8in8CONTROL8domain8instead8of8data8domain

3.8worked8towards8NETWORK-
WIDE8visibility8and8control8rather8than8device8level8configurations(7)

Was8visibility8and8control8at8network8level8or8device8level8for8active8networks?8Control/
data8plane8separation?8-8answer--Device8level

Network8level
(7)

Was8programmability8in8control8domain8or8data8domain8for8active8networks?8Control/
data8plane8separation?8-8answer--Data8domain

control8domain
(7)

Was8innovation8for8network8admins8or8users8for8active8networks?8Control/
data8plane8separation?8-8answer--Users

Admins

(7)

What8are858use8cases8for8control8plane/data8plane?8-8answer--
1.8path8selection8based8on8network8traffic8load

2.8minimized8disruptions8during8planned8routing8changes

3.8redirecting8or8dropping8suspected8attack8traffic

4.8allow8customer8networks8more8control8over8network8flow

5.8offer8value8added8services8for8virtual8private8network8customers
(7)

Were8control8plane8and8data8plane8separation8efforts8focused8on8managing8routing8WIT
HIN8ONE8ISP?8-8answer--No

some8wanted8to8enable8flexible8route8control8across8many8ASes

(7)

What828concepts8resulted8from8control8and8data8plane8separation?8-8answer--
1.8LOGICALLY8centralized8control8w/8open8interface8to8data8plane