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question about Eigrp and CCIE written
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| Hi, during my CCIE written preparation, I found following topics of EIGRP is confusing.
1) Is MTU part of routing metric of EIGRP/IGRP?
I know MTU is not count towards the composite metric according to the metric formula. some book ( i.e. ICND book )did state MTU is one of the 5 composite metric. so what will be the answer be if I see the question in CCIE written?
2) what's EIGRP's max hop count?
it's 224 or 255 ? ( I know IGRP's max hop count is 255, my instructor said it's 224 for eigrp but I never see the proof in book )
3) is EIGRP distance vector protocol?
different book has different version on this one. some book stated it's distance vector protocol with link state feature; some book stated it's hybrid and therefore not distance vector protocol. what will be the answer in CCIE written then?
and one more question regarding CCIE written format: for the " choose all that reply " type of question, is it possible to have only one correct answer?
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| Hammer555 2002-07-01, 8:48 am |
| 1) MTU is part of the composite metric but is set to zero by default (k5=0 so it wont be used), a question on metric will probably ask the default metrics - so the answer will be no (it can be used if you want though).
2)EIGRP using the same metric as IGRP multiplied by 256 so I always thought that the max hop count was 255. The Hop count in the header is a field ranging from 0x01 to 0xff so I dont see why it would not be 255.
3)EIGRP is a distance vector protocol - it is certainly not link state. | |
| Hammer555 2002-07-01, 8:51 am |
| almost forgot. . . .you will have to have all the correct answers in 'all that apply' no partial credit - its all or nothing. | |
| hobbit 2002-07-01, 12:57 pm |
| I always thought that EIGRP was neither link state nor is it distance vector, but what they call a hybrid protocol.
Perhaps someone else could clear this up.
pj | |
| ZacDogg 2002-07-01, 1:33 pm |
| EIGRP is a distance vector protocol, it just has some link state characteristics. | |
| lcooper 2002-07-01, 2:23 pm |
| According to Cisco; Eigrp is an enhanced distance-vector routing protocol. Many Cisco documents categorize EIGRP as a " hybrid " routing protocol that discovers network like a distance-vector protocol, but it adjust to changes in network similar to a link state routing protocol. However, EIGRP is not a link state protocol. | |
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| I passed 350-001 on Saturday with 80%. Not a great score, and it's the hardest test I took so far. Well, it's good for 18 months, I may need some break before going for the lab.
For those who might intestested, there was a " chhose all that apply " question about EIGRP. I chose eigrp as distance vector. I hope that's the answer CISCO wants.
It took me good 115 mins to finish all the 100 questions.
I like the option that you can go back to the questions you marked although I don't have too much time left to review.
This forum has been a great help, thanks all! | |
| cahillrobert 2002-07-08, 8:55 pm |
| from jwu2quote:
I passed 350-001 on Saturday
Congratulations on your success.
Bob | |
| rsteedma 2002-07-09, 10:28 am |
| MTU is not part of the EIGRP metric.
It's a "useless piece of info" carried in EIGRP routing updates. 
>>>>>>>>>>>>>>>
metric = [k1 * bandwidth + (k2 * bandwidth)/(256 - load) + k3 * delay]
If k5 does not equal zero, an additional operation is performed:
metric = metric * [k5/(reliability + k4)]
>>>>>>>>>>>>>>>
Cheers,
Ron | |
| cjfarnold 2002-07-15, 11:13 pm |
| [QUOTE]Originally posted by jwu2
[B]Hi, during my CCIE written preparation, I found following topics of EIGRP is confusing.
1) Is MTU part of routing metric of EIGRP/IGRP?
MTU is included in the formula but it is not been used as part of the metric calculation.
2) what's EIGRP's max hop count?
eigrp is a distancevector protocol withlink state capabilities hence it uses metic and does not use hop count to determine if a host or network is un reacheable)
3) is EIGRP distance vector protocol?
Enhanced IGRP integrates the capabilities of link-state protocols into distance-vector protocols. It
incorporates the Diffusing-Update Algorithm (DUAL) | |
| rsteedma 2002-07-16, 12:45 am |
| Hi Arnold,
The default maximum hopcount for EIGRP is 100, as shown in the output below.
It can be configured up to 255.
The purpose of the EIGRP hopcount is to detect routing loops - hopcount is NOT part of the EIGRP metric.
Routing Protocol is "eigrp 301"
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
EIGRP maximum hopcount 100
EIGRP maximum metric variance 1
Redistributing: eigrp 301
Automatic network summarization is in effect
Routing for Networks:
172.20.0.0
Routing Information Sources:
Gateway Distance Last Update
172.20.52.1 90 00:00:49
172.20.52.22 90 00:00:49
172.20.52.19 90 00:00:49
172.20.52.121 90 00:00:49
Distance: internal 90 external 170
Cheers,
Ron |
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