CCDA/CCDP - Any ATM gurus here?

Author

Any ATM gurus here?

meijin

2003-04-29, 11:19 am

I was working on an internal company pre-test on ATM and there were several questions that I was not sure about or that I could not find the answers to. Any of you ATM gurus here want to take a shot and help me out?

Here they are:

#1. The ATM Forum defines which service category as "best effort"? **

Choice 1 Real-Time Variable Bit Rate (rt-VBR)
Choice 2 Available Bit Rate (ABR)
Choice 3 Constant Bit Rate (CBR)
Choice 4 Unspecified Bit Rate (UBR)
Choice 5 Non-real-time Variable Bit Rate (nrt-VBR)

#2. You have installed an ATM switch with 16 ports each at 155 megabits per second (Mbps). **
To be considered nonblocking, the switch described above requires how much aggregate throughput?

Choice 1 About 155 megabits per second (Mbps)
Choice 2 About 622 megabits per second (Mbps)
Choice 3 About 1.2 gigabits per second (Gbps)
Choice 4 About 2.5 gigabits per second (Gbps)
Choice 5 About 9.9 gigabits per second (Gbps)

#3. Which one of the following Service Categories provides guarantees for Loss, Bandwidth, and Feedback Control? **

Choice 1 Unspecified Bit Rate (UBR)
Choice 2 Real-Time Variable Bit Rate (rt-VBR)
Choice 3 Available Bit Rate (ABR)
Choice 4 Non-real-time Variable Bit Rate (nrt-VBR)
Choice 5 Constant Bit Rate (CBR)

#4. An ATM-capable router that manages the traffic between two separate emulated or virtual LANs supports how many instances of the LEC, one for each emulated LAN? **

Choice 1 1
Choice 2 2
Choice 3 3
Choice 4 4
Choice 5 6

#5. In which layer is the Segmentation & Reassembly Sublayer found? **

Choice 1 Application Layer
Choice 2 User Layer
Choice 3 Physical Layer
Choice 4 ATM Layer
Choice 5 ATM Adaptation Layer

#6. Which one of the following PHY levels does the ATM layer use? **

Choice 1 Digital Section
Choice 2 Transmission Convergence
Choice 3 Regenerator Section
Choice 4 Analog Section
Choice 5 Physical Medium Dependent Sublayer

#7. Approved by the ATM Forum in 1997, Inverse Multiplexing over ATM (IMA) falls into which one of the following standards? **

Choice 1 User-to-Network Interface (UNI) standard
Choice 2 Signaling guidelines for Classical IP standard
Choice 3 Network-to-Network Interface (NNI) standard
Choice 4 Broadband Integrated Services Digital Network (BISDN) standard
Choice 5 Private Network-to-Network Interface (P-NNI) Phase 1 standard

#8. In LANE operation, after the LEC obtains the LES address, the LEC optionally clears the connection to the LECS, sets up the control-direct VCC to the LES, and sends what message on that VCC? **

Choice 1 LE_CONFIGURE_REQUEST
Choice 2 LE_ARP_REQUEST
Choice 3 LE_JOIN_RESPONSE
Choice 4 LE_JOIN_REQUEST
Choice 5 LE_CONFIGURE_RESPONSE

#9. Bandwidth and buffer resources must be made available on a per-connection basis at all times.
Based on the above, to which one of the following sets of guaranteed-QoS service classes must these resources be made available? **

Choice 1 CBR, nrt-VBR, and rt-VBR
Choice 2 ABR, CBR
Choice 3 UBR, nrt-VBR, and rt-VBR
Choice 4 ABR, UBR
Choice 5 ABR, nrt-VBR, and rt-VBR

#10. The User-to-Network Interface (UNI) contains header fields that are NOT contained in the Network-to-Network Interface (NNI). **
Referring to the above, which one of the following header fields is contained in the UNI, but NOT in the NNI?

Choice 1 Payload Type ID
Choice 2 Virtual Path Identifier
Choice 3 Virtual Channel Identifier
Choice 4 Header Error Control
Choice 5 Generic Flow Control

Thanks for any help you can provide.

anchor40

2003-04-29, 2:14 pm

1. Best Effort is Unspecified Bit Rate
2. 16 * 155MB = 2.5GB/s (OC-48)
3. ABR
4. (wording?) One LEC per ELAN
5. AAL
6. 2 and 5:
From Sourcebook of ATM and IP Internetworking
Khalid Ahmad
Copyright © 2002 Institute of Electrical and Electronics Engineers, Inc.

The physical layer functions are sublayered into the so-called transmission convergence (TC) sublayer and the physical medium (PM) dependent sublayer (also known as PMD sublayer).
The functions in the TC sublayer include:
Cell rate adaptation
Cell delineation
HEC processing
Transmission frame adaptation/generation
Transmission overhead processing

The functions in the PM sublayer include:
Bit timing
Line coding
Adaptation to physical medium
Connector related functions

7. 1 and 3 (from page 12, ftp://ftp.atmforum.com/pub/approved-specs/af-phy-0086.000.pdf )

8. LE_ARP_REQUEST to obtain a LEC identifier (LECID)
9. 2-ABR and CBR. Constant Bit Rate means a guaranteed amount of bandwidth is available all the time, and Available Bit Rate must be able to buffer when adjusting the bandwidth according to the network conditions.
10. Generic Flow Control

HTH...

meijin

2003-04-29, 3:15 pm

See...I knew someone like you needed something to this afternoon!

Actually, I ended up finding all but two of the answers over the last several hours. My God is there a ton of ATM related material out there on the Net!!!

With regards to #6, I found the answer to be Choice #2

With regards to #7, I found the answer to be Choice #1.

Could you live with that if you cannot have a multiple option answer? I found the references, but don't ask me what they are now.

Thanks very much for the help!

anchor40

2003-04-29, 5:03 pm

That's funny, because I found #6 in the IEEE published book on ATM, and the answer to #7 right off the ATM Forum's whitepaper on IMA 1.0!

I personally would trust those sources over a third party study guide. The good news is that the Cisco tests now have the "Choose X" for the multiple-guess and won't leave you wondering if you forgot to check one. You might not check the right answers, but you'll check the right NUMBER of answers!

I guess that goes to show that not all study guides are created equal!

meijin

2003-04-29, 6:58 pm

Well, maybe I was just reading it wrong. There was no study guide, I was finding info on the Internet. This is an internal assessment. I did find the ATM Forum site and that is where I got some of my info.

I took the test late this afternoon and passed it with an assessment score of 2.94 out of 5. I had to have a 2.75 or better.

Thanks again for the help. On to Frame Relay and ISDN!

What are you doing later?

wirelessboy

2003-04-29, 9:21 pm

well meijin no atm gurus in cwnp forum!

what test in ATM, any specific test on that.

meijin can u check out my Frame relay doubt in ccnp forum

thanks

meijin

2003-04-29, 9:31 pm

I said I had to take an accessment on Frame Relay, not that I was expert at it. I'm not sure I am the person you want trying to troubleshoot that!

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