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Drag and Drop Questions

October 19th, 2010 in CCIE Written Go to comments

Here you will find answers to Drag and Drop Questions

Question 1

Drag the items to the proper locations

QoS_Features.jpg


Answer:

Classification —> near the edge network
Queuing —> congestion management
Marking —> packet differentiation
RED —> drop packets
Shaping —> tail drop
Policing —> inbound interface

Explanation

Classification entails using a traffic descriptor to categorize a packet within a specific group to define that packet and make it accessible for QoS handling on the network. For example, you can use classification to mark certain packets for IP Precedence. IP Precedence is usually deployed as close to the edge of the network or the administrative domain as possible.

Queuing is designed to accommodate temporary congestion on a network device’s interface by storing excess packets in buffers until bandwidth becomes available.

When a queue is full, IOS has no place to put newly arriving packets, so it discards them. This phenomenon is called tail drop. Often, when a queue fills, several packets are tail dropped at a time, given the bursty nature of data packets.

Marking allows the QoS level of the packet to change based upon classification or policing. Tail drop is the default drop mechanism.

Traffic shaping prevents the bit rate of the packets exiting an interface from exceeding a configured shaping rate. To do so, the shaper monitors the bit rate at which data is being sent. If the configured rate is exceeded, the shaper delays packets, holding the packets in a shaping queue. The shaper then releases packets from the queue such that, over time, the overall bit rate does not exceed the shaping rate.

Random Early Detection (RED) monitors the average queue size and drops packets based on statistical probabilities. If the buffer is almost empty, all incoming packets are accepted. As the queue grows, the probability for dropping an incoming packet grows too. When the buffer is full, the probability has reached 1 and all incoming packets are dropped.

Shaping implies the existence of a queue and of sufficient memory to buffer delayed packets, while policing does not. Queuing is an outbound concept; packets going out an interface get queued and can be shaped. Only policing can be applied to inbound traffic on an interface. Ensure that you have sufficient memory when enabling shaping. In addition, shaping requires a scheduling function for later transmission of any delayed packets. This scheduling function allows you to organize the shaping queue into different queues. Examples of scheduling functions are Class Based Weighted Fair Queuing (CBWFQ) and Low Latency Queuing (LLQ).

Comments
  1. CCIE Lerner
    February 19th, 2011

    hi! can anybody explain this two below… im confuse:

    Marking —> packet differentiation? answer. Marking — tail drop?
    Shaping —> tail drop? answer: Shaping– packet differentiation?

    Marking —- Tail drop is the default drop mechanism.
    Shaping —- prevents the bit rate of the packets exiting an interface from exceeding a configured shaping rate….. packet differentiation?

  2. Jason
    February 21st, 2011

    I think RED should be connected with Tail Drop. RED provide a machisme to avoid tail drop.

  3. DBurger
    February 25th, 2011

    I think Marking and Classification are mixed. You always Mark your traffic ‘near the edge of the network’ yet ALL policy maps rely on classification be it classifying traffic that has already been marked BY a device at the edge of the network or classifying traffic via NBAR or ACL so you can Mark it ON a device at the edge of the network

    So….I believe it should be:

    Classification —> packet differentiation
    Marking ———-> near the edge of the network.

  4. DBurger
    February 25th, 2011

    Jason – although you are correct that WRED does provide a mechanism to avoid tail drops, a better choice for WRED is ‘drop packet’ as this option doesn’t go well with any other item in the list. In addition, although the object of WRED is to prevent tail drop, you will experience taildrop in a queue if it gets full.

  5. pOp
    May 28th, 2011

    Though it is mentioned as -> Classification & Marking.But in real it is Marking & Classification.

    You Mark the packets that needs to be Classified.

  6. Josh6226
    May 30th, 2011

    I think the correct answers are :

    Classification —> near the edge network
    Queuing —> congestion management
    Marking —> packet differentiation
    RED —> tail drop
    Shaping —>inbound interface
    Policing —>drop packets

    explanation :

    For classification—On ingress only, and only if the interface supports that particular header
    field
    For marking—On egress only, and only if the interface supports that particular header field

    Tail drop is a mechanism of RED.

    If the configured rate is exceeded, the shaper delays packets, holding the packets in a shaping queue.So shaping does not drop the packet , but policing does.

  7. lonesomeboy
    May 30th, 2011

    @Josh6226.

    Shaping can not be configured on the inbound interface so you’re answer can’t be correct.

    Policing and dropping. Yes it can be associated this way but policing can remark and also allows traffic through even though it exceeds or violates part of the traffic contract. The dropping fits a whole lot better with RED as that’s the whole point of it i.e. D stands for Dropping. I nearly made the same mistake.

    @DBurger

    I think it’s the other way around. You can’t actually mark traffic until it’s been classified by some ACL, failure to meet a traffic contract etc. except in certain circumstances i.e. Adaptive Shaping with BECN etc. so the better answer is…

    Classification —> near the edge network
    Queuing ——–> congestion management
    Marking ——–> packet differentiation
    RED ————-> drop packets
    Shaping ——–>tail drop
    Policing ———>inbound interface

    Which match rstut’s view.

    With Marking being packet differentiation as it’s only with the DSCP type options that you get granularity.

    I suspect that with the amount of overlap between the options there’s more than one version of the answer.

  8. Benson Lei
    May 31st, 2011

    RED — > Tail drop

    P536 — CCIE R&S edit 2009

    When a queue is full, IOS has no place to put newly arriving packets, so it discards them. This phenomenon is called tail drop.

  9. lonsomeboy
    June 8th, 2011

    @Benson Lei

    Tail drop happens to any queue that gets full.

  10. Benson Lei
    June 13th, 2011

    so many comments and books, which is the correct answer ?

  11. NetworkPlayer2010
    June 21st, 2011

    Hey Guys,

    I developed a SWF file for this DnD:

    Download ZIP / UnZip and run quiz.html …..enjoy 🙂

    http://www.4shared.com/file/nOwX0ZwZ/Drag_n_Drop.html

    quiz.html
    quiz.swf

  12. Amit
    June 22nd, 2011

    100% agree with Rstut on Question 1:

    Answer:

    Classification —> near the edge network
    Queuing —> congestion management
    Marking —> packet differentiation
    RED —> drop packets
    Shaping —> tail drop
    Policing —> inbound interface

  13. Gary
    July 7th, 2011

    Just to share an “official” explanation on Shaping and Policing

    http://www.cisco.com/en/US/tech/tk543/tk545/technologies_tech_note09186a00800a3a25.shtml

  14. rstut_correction
    July 9th, 2011

    Marking —> near the edge network
    Queuing —> congestion management
    Classification —> packet differentiation
    Shaping —> drop packets
    RED —> tail drop
    Policing —> inbound interface

  15. dave
    July 11th, 2011

    is this the right answer?

    Marking —> near the edge network
    Queuing —> congestion management
    Classification —> packet differentiation
    Shaping —> drop packets
    RED —> tail drop
    Policing —> inbound interface

  16. Ram Cheerath
    July 11th, 2011

    Hi friends

    Some friend are posting here Drag N drop was changed , some words are changed , what is new drag n drop and answers ?

  17. Doug NoLan
    July 12th, 2011

    Is it correct words of Drag & Drop ?

    Marking —> near the edge network
    Queuing —> congestion management
    Classification —> packet differentiation
    Shaping —> drop packets
    RED —> tail drop
    Policing —> inbound interface

    What is new words of drag & drop ,someone post earlier in this form ? ( explanations in the right side are different.)

    Anyone can Explain ?

  18. rstut_correction
    July 17th, 2011

    Which answer is correct ?

    1 –

    Classification —> near the edge network
    Queuing —> congestion management
    Marking —> packet differentiation
    RED —> drop packets
    Shaping —> tail drop
    Policing —> inbound interface

    or

    2 –

    Marking —> near the edge network
    Queuing —> congestion management
    Classification —> packet differentiation
    Shaping —> drop packets
    RED —> tail drop
    Policing —> inbound interface

  19. Benson Lei
    July 18th, 2011

    after having read a lot of material — traffic shaping is used to shape the traffic under a criterion ( not drop the traffic ) and delay the traffic until bandwidth is available again..

  20. Benson Lei
    July 18th, 2011

    Just clear the CCIE written over this weekend

    DnD is similar but more difficult…the wording is not a simple word again, but a sentence…
    do please fully understand the full meaning…not just hard push in your mind.

  21. the one how knows it
    July 21st, 2011

    Policing —> paket drop
    Shaping —> tail drop
    RED —> packet differentiation
    Queuing —> congestion management
    Marking —> near the edge
    Classification —> inbound interface

  22. Sanjana Chopra
    July 28th, 2011

    I got 1000/1000

    My Drag N Drop Answer is

    Classification —>>> At the access layer
    Queuing —>>> Congestion management
    Marking —>>> Packet differentiation
    RED —>>>Discovered to alleviate tail drop
    Shaping —>>>Blocked on applying to inbound interface
    Policing —>>> Drop excess traffic

  23. Padmini
    July 30th, 2011

    Hi zain and sanjana

    Could u please help me to understand the 4sim.Still i have a confusion on that.

    Thanks and Regards
    Padmini

  24. jonkeneda Hdp
    August 3rd, 2011

    Is it correct words of Drag & Drop ?

    Marking —> near the edge network
    Queuing —> congestion management
    Classification —> packet differentiation
    Shaping —> drop packets
    RED —> tail drop
    Policing —> inbound interface

    What is new words of drag & drop ,someone post earlier in this form ? ( explanations in the right side are different.)

    Anyone can Explain ?

  25. Test
    August 13th, 2011

    I got 1000/1000 ,too

  26. Ram
    August 16th, 2011

    Is this the correct answer

    Marking —> near the edge network
    Queuing —> congestion management
    Classification —> packet differentiation
    Shaping —> drop packets
    RED —> tail drop
    Policing —> inbound interface

  27. Waheedullah Khan
    September 13th, 2011

    Mrs Sanjana chopra,

    You got 1000/1000 but we are discus here another D&D. If you know the right answer of following D&D so tell us what is right?

    Classification —> near the edge network
    Queuing ——–> congestion management
    Marking ——–> packet differentiation
    RED ————-> drop packets
    Shaping ——–>tail drop
    Policing ———>inbound interface

    Marking —> near the edge network
    Queuing —> congestion management
    Classification —> packet differentiation
    Shaping —> drop packets
    RED —> tail drop
    Policing —> inbound interface

    Marking —> near the edge network
    Shaping —> congestion management
    Classification —> packet differentiation
    Policing —> drop packets
    RED —> tail drop
    Queuing —> inbound interface

  28. Anonymous
    September 14th, 2011

    Can anyone tell me about sim? In the sim will be provide console for run command? Or just need the select answer?

  29. XXX
    September 25th, 2011

    RED is Drop packet. You can go to wiki to check the answer.
    RED drop the packet before tail drop happened.

  30. XXX
    September 25th, 2011

    Sanjana Chopra …. How did you get 1000 point? 😀

  31. XXX
    September 25th, 2011

    – Classification: The process used to select the traffic to be marked.
    so that it must be at Access-layer.
    -Marking: It should be at DS-Layer (Layer 3)or it can implement at Access-Layer (layer2)

    Rstut is correct

  32. XXX
    September 25th, 2011

    Shaping can apply on the outbound interfact only. Policing can apply inbound/outbout.
    so that policing >> inbound (correct)
    Shaping: keep the packet to the queue when the traffic over rate limit. Over rate packets will keep in the queue when the queue is full. The tail drop will happen…

  33. Fabio Teixeira
    September 29th, 2011

    I passed in CCIE Written today (09/29/11) with 976

    This question, the correct answer is

    Classification —>>> At the access layer
    Queuing —>>> Congestion management
    Marking —>>> Packet differentiation
    RED —>>>Discovered to alleviate tail drop
    Shaping —>>>Blocked on applying to inbound interface
    Policing —>>> Drop excess traffic

  34. Jacklyn
    October 16th, 2011

    Umm, are you really just giivng this info out for nothing?

  35. sami
    November 18th, 2011

    i took the exam and i fail with 650 🙁 very bad score .. i forget every thing and i didnt study well .. but im gonna try again in 2 month !!!

  36. Anonymous
    November 27th, 2011

    i agree with rstut solution and here my reasons:
    1- let us match the choices whisch we all agree upon:
    Classification —> near the edge network
    Queuing —>>> Congestion management
    Marking —> packet differentiation
    note Cisco defines Queueing as congestion management, and defines Policing and shaping as traffic regulation.

    2- we have now 3 choices, let begin us with policing:
    drop packets is not policing behvior, policing drop exccess traffic.
    so we have 2 choices that could match policing, but tail drop won’t fit here because it is a general QOS behaviour so it is unlikely to be chosen, because there is another more specific choice which is inbound interface, so my choice would be:
    Policing ———>inbound interface

    3- now we look at RED:
    again tail drop won’t fit here because it is a general QOS behaviour so it is unlikely to be chosen because there is another more specific choice which is Drop Packet, and Drop Packets is the RED main function, so my choice would be:
    RED ————-> drop packets

    4- now we are left with the only choice, which is:
    Shaping ——–>tail drop
    and this will fit because when a shaping queue is full, it will begin tail drop.

  37. MRK
    November 29th, 2011

    as you know the answer is wrong please correct it.

  38. Axe79
    November 29th, 2011

    mrk
    i wrote the comment on the 27th of Novemebr
    do you mean that my answer is wrong, if yes state your reasons

  39. ExpertNET
    November 30th, 2011

    I agree with you, Fabio.

    I think correct answer must be this:

    Classification —> At the access layer
    Queuing —> Congestion management
    Marking —> Packet differentiation
    RED —> Discovered to alleviate tail drop
    Shaping —> Blocked on applying to inbound interface
    Policing —> Drop excess traffic

  40. Spacey
    December 1st, 2011

    This came up for me in Nov 2009 but the Pink options were:
    NOT ON AN Inbound I/F **
    Discards excess traffic
    Differentiation of packets
    Congestion Management
    AVOIDS THE Tail Drop effect **
    Implemented at the Access Layer

    The two with ** are the opposite to RStut

    I’m sitting this again tomorrow so if it comes up I’ll report back.

  41. jep
    December 13th, 2011

    to clear up classfication vs marking

    http://www.cisco.com/en/US/technologies/tk543/tk766/technologies_white_paper09186a00800a3e2f_ps6610_Products_White_Paper.html –> see figure 5. Traffic Conditioner Block (TCB)

    Classification is selecting. it’s a capability of indentification in order to differ packets. access list, seeing ip prec or dscp bit set in the packet, match are tools for classification. Marking is writing or rewriting packets (let say, don’t trus the original dscp) or choose not to drop packets but giving it dscp value for another classification at next hop router. deploying ip prec and dscp bit in packet is doing marking.

    classification and marking should be performed as close to the edge of the network as possible. and i think classification and marking are both used for packet differentiation.

    hey then: marking is done by client device near the edge network before classification? could be true. Traffic classifiers may honor any DiffServ markings in received packets or may elect to ignore or override those markings. But, it is very rare that the network honors markings at the ingress to the DiffServ domain. So, what actually happens is the network doing traffic classfication based on: access list (source dest ip, protocol,etc),or just trust ip prec/dscp and assign them to separate class. Based on marking in each separate class, we apply policy (shaper/dropper or rewrite) on egress.

    i agree with rstut answer:
    Classification —> near the edge network
    Queuing —> congestion management
    Marking —> packet differentiation
    RED —> drop packets
    Shaping —> tail drop
    Policing —> inbound interface

  42. Nikhil
    December 31st, 2011

    Jep: was was your answer for this question in the exam…
    Plz share us ..

  43. jep
    January 13th, 2012

    @Nikhil, i see in other page you had overcome ccie written;-) congrats. lets prepare for LAB.

  44. Matt
    January 14th, 2012

    I guess I will go with the answer that most agree on and RSTUT gives but I would have swapped classification and marking around since:

    Although marking without classifying is almost useless (except when implicitly using source interface to classify) marking needs to be done once near the edge.

    Classification and packet differentiation are done both when classifying and marking at the edge, and at all hops in network that use QoS congestion management tools, so I personally would think the best answer is:

    Marking —> near the edge network (Marking should be done near edge and only once)
    Queuing —> congestion management
    Classification —> packet differentiation (true and at each QoS hop)
    RED —> drop packets
    Shaping —> tail drop
    Policing —> inbound interface

    Just another contentious question I guess

    Good luck
    Matt

  45. Anonymous
    January 30th, 2012

    This question, the correct answer is

    Classification —>>> At the access layer
    Queuing —>>> Congestion management
    Marking —>>> Packet differentiation
    RED —>>>Discovered to alleviate tail drop
    Shaping —>>>Blocked on applying to inbound interface
    Policing —>>> Drop excess traffic

  46. already CCIE
    February 11th, 2012

    So this question is not really as it’s asked at the top.
    Looks like, real question is actually something like the Anonymous sent above.
    Answers are logical with those as well. Case resolved.

  47. Alwin
    February 17th, 2012

    HI All,

    If the below is the answer and Question in Exam, I believe that is correct answer.

    Classification —>>> At the access layer
    Queuing —>>> Congestion management
    Marking —>>> Packet differentiation
    RED —>>>Discovered to alleviate tail drop
    Shaping —>>>Blocked on applying to inbound interface
    Policing —>>> Drop excess traffic

  48. Alwin
    February 17th, 2012

    If the answer and Question is same like this forum, I think its very confusing.
    I think below is the most closer answer but I believe sometime the correct answer
    might wrong in exam.

    The Tail drop is actually on RED, WRED and FIFO, but all are under congestion avoid management, that why the answer and Question is very confusing.

    Policing —> Drop packets – Quite sure
    RED —> Tail drop – Quite sure
    Queuing —> congestion management
    Marking —> packet differentiation

    The most possible answer
    Classification —> inbound interface ( should apply to inbound and outbound traffic )
    Shaping —> near the edge network

  49. Alwin
    February 17th, 2012

    Hi Fabio Teixeira

    Appreciate if you could confirm the Question and Answer that you post is actualty the one come out in the Exam and not the one in this forum. Thank

  50. Luca
    February 19th, 2012

    Hey Guys. The current DnD question inclusive the correct answer can be found in Spike’s latest dump (confirmed to be valid by many users) via: http://www.examcollection.com/cisco/Cisco.Pass4sure.350-001.v2012-01-31.by.Spike.208q.vce.file.html
    Sanjanas dump which has also been confirmed as valid shows the same DnD question and solution. It can be found here: http://www.examcollection.com/cisco/Cisco.ActualTest.350-001.v2011-08-01.by.SanjanaChopra.156q.vce.file.html

  51. Jesica
    February 6th, 2013

    In short TUT answers are correct.

    However note that there are two type of DnDs. One that is on this page which is correct.

  52. Prasad!!
    June 1st, 2013

    Sanjana @ You are right

  53. Blakeley64
    February 2nd, 2016

    Ideas that are arranged in double columns and placed in frames improve the common data in each and every chapter, and The word of mouth advice that pops up every single now and then is enjoyable, entertaining, and informative.

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