CCIE Pursuit Blog

September 14, 2007

Time Range Question Confusion

Filed under: CCIE Lab Workbooks,Cisco,Cisco Certification,IOS,Lab Tips — cciepursuit @ 1:06 pm

This post on GroupStudy brings up an excellent point:

I recently did a lab (IEv3 lab 16) and got a question to stop admins using quake in business hours (not including the lunch hour).

I did the whole acl/time range thing and put in

09:00 to 12:00
13:00 to 17:00

When I checked the answer it was actually.

09:00 to 11:59
13:00 to 16:59

I know “close isn’t good enough, etc etc etc” but is my answer really incorrect?

The question said they work from 9am til 5pm it did not say that they finish and infinitely small amount of time before 5pm.  The actual answer in the solutions guide does not encompass the exact moment that 17:00 happens so in many ways I feel that my 59secs out answer is still as correct as the solution.  To be honest though I’m not too bothered don’t about the laws of physics just the points that I didn’t give myself over something so little.

Anyway my question(s).
Are the really going to questions that picky on the actual lab?
Would I have got that wrong in the exam?
How do you know the person on the exam wont look at the answer “16:59” and think “smart ass, I actually said 17:00 not 16:59, wrong”

Could you argue that the correct solution is really a matter of perspective? (ie 16:59 ends at 16:59999999999999999999999999999999999999′ , actually before the moment of 17:00)

This is definitely an “ask the proctor for clarification” issue, but here are a few of the better replies (including two from the vendors):

Funny enuf, I’ve experienced this several times, questioning vendors and proctors what an acceptable interpretation really is.

Let me just highlight few points from what I gathered, using the your case-study:

1. For most business hours, employees work for 3 hours(180minutes) in the morning and then 5 hours (300minutes) after launch.
2. so if you start work for 09:00, and work for 180 minutes, at the 181st minute, you’re not expected to be working right? Which means the solution should be 09:00 – 11.59 right?
3. same thing will apply to 13:00 to 16:59, as that range has got 300minutes within it, anything into 17:00 will mean 301minutes of work.

So the way you plan your time-range acl will depend on what is required in the question. If I don’t want my staff to use quake during work hours, which mean they can use it outside work hours. 11.59 is still part of work hours because that’s the 180minute of work in the morning, the 181st minute is outside work hours … 12:00, so staff can use the quake at this time 181st minute.

However, like I said earlier, it depends on the requirement of the question, you could well be required to configure an acl to include span across 9.00 to 12.00 literally, in this case your best bet will be to check with your proctor and let him know what you’re thinking, if your proctor is having a nice/good day, they will usually help explain the grey areas around tasks … But Proctors are not allowed to give you answers as you know!

Many Thanks

Yemi Salau

*****

It’s a topic that’s been discussed a few times before.  Since we give the information in minutes the detail comes in about seconds.  08:00 to 16:59 really means 08:00:00 to 16:59:59 or “TO” 5pm.

IMHO, the proctor isn’t going to be THAT picky about it, that’s more a semantic argument than a knowledge thing.  But one never knows!

It’s better to be technically accurate than wondering the back of your mind whether you were counted off or not!  🙂

We’ll avoid the other semantic argument on how reliable the clocking chips on the routers we use in labs are anyway!  Heheheh…

Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-J
VP – Technical Training – IPexpert, Inc.
IPexpert Sr. Technical Instructor

A Cisco Learning Partner – We Accept Learning Credits!

***** 

The point is that when I take lunch, it’s exactly at 12:00 and not at 12:01.  I don’t want the man to get getting that extra minute 😉

Seriously though I wouldn’t worry about this level of detail.  If you’re concerned about this at the exam time just ask the proctor.  Also the time range on the router isn’t a real time process.  Even though you say 11:59 the process may not come into affect until 11:59:30.239 and not necessarily 11:59:00.000

HTH,

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan@xxxxxxxxxxxxxxxxxxxxxx

Internetwork Expert, Inc.
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Dynamips On Mac Mini Blog

Filed under: CCIE Blogs,Cisco,Cisco Certification,Dynamips,Home Lab,Training Materials — cciepursuit @ 12:17 pm

For all of you Mac-Heads out there, Scott from the GroupStudy list is blogging about his experiences with setting up Dynamips of a Mini Mac with 4 live, eight-port 3560s as a CCIE lab.  He’s using the Internetwork Expert lab topology. 

IT Artisans’ Dynamips Blog

Frame Relay Encapsulation Mismatches

Filed under: Cisco,Cisco Certification,IOS — cciepursuit @ 12:11 pm

Frame Relay encapsulation is pretty straight-forward: you need to match your encapsulation (IETF or Cisco) with the encapsulation on the device(s) on the other end of your Frame Relay link.  Technically, you don’t need to have matchin encapsulation,  as I just found out today:

The main reason why one will use the ‘IETF’ encapulation is because the third party vendor do not understand Cisco’s ‘CISCO’ encapsulation so they would not be able to decapsulate packets sent to them with ‘CISCO’ encapsulation.

Cisco went a mile further and as such Cisco routers understands both ‘IETF’ and ‘CISCO’ encapsulations. When this near-end router uses ‘CISCO’ encapsulation, it merely means that at layer 2, it is going to encapsulate all out going packets with “CISCO encapsulating Language engine” incoming packets can be decapsulated even if they are coming as ‘CISCO’ or ‘IETF’ . The same logic applies when the far end router have ‘IETF’ as its ‘encapsulating language’

In essence, ‘frame-relay encapsulation CISCO’ or ‘frame-relay encapsulation IETF’ only applies to how this router will encapsulate its outgoing packets and not decapsulating incoming packets. Since third party routers do not have the Cisco’s proprietary ‘CISCO encapsulation engine’ in their products, hence one have to use ‘IETF’ encapsulation when talking to them.

The poster goes on to prove this with some debugs.  So you could have a Frame Relay encapsulation mismatch between the devices and still be able to communicate if both ends are Cisco devices.  If the device on the other end of the link is a 3rd party router or you are unsure of what type of device is on the other end of the link, then use “frame-relay encapsulation ietf”.


Cisco Documentation

encapsulation frame-relay

Frame Relay Configuration Guide

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