UC知道[求助]eigrp variance与路由选择的问题
来源：百度知道 编辑：UC知道 时间：2024/06/20 07:29:14
QUESTION 35
The Certkiller EIGRP network is shown below:
[IMG]http://new.51cto.com/files/uploadimg/20080731/100717275.jpg[/IMG]
You work as a network technician at TestKing.com. Study the exhibits carefully. If
the command "variance 3" was added to the EIGRP configuration of TestKing5,
which path or paths would be chosen to route traffic from TestKing5 to network X?
A. TestKing5-TestKing2-TestKing1
B. TestKing5-TestKing2-TestKing1 and TestKing5-TestKing3-TestKing1.
C. TestKing5-TestKing3-TestKing1 and TestKing5-TestKing4-TestKing1.
D. TestKing5-TestKing2-TestKing1,TestKing5-TestKing3-TestKing1, and
TestKing5-TestKing4-TestKing1.
Answer: B
Explanation:
In this question the variance 3 command is used. Since the lowest metric is 10. 10*3 = 30
meaning we can use all routes with a metric of 30 and
The Certkiller EIGRP network is shown below:
[IMG]http://new.51cto.com/files/uploadimg/20080731/100717275.jpg[/IMG]
You work as a network technician at TestKing.com. Study the exhibits carefully. If
the command "variance 3" was added to the EIGRP configuration of TestKing5,
which path or paths would be chosen to route traffic from TestKing5 to network X?
A. TestKing5-TestKing2-TestKing1
B. TestKing5-TestKing2-TestKing1 and TestKing5-TestKing3-TestKing1.
C. TestKing5-TestKing3-TestKing1 and TestKing5-TestKing4-TestKing1.
D. TestKing5-TestKing2-TestKing1,TestKing5-TestKing3-TestKing1, and
TestKing5-TestKing4-TestKing1.
Answer: B
Explanation:
In this question the variance 3 command is used. Since the lowest metric is 10. 10*3 = 30
meaning we can use all routes with a metric of 30 and
这两个题是考查的EIGRP负载均衡。
只有满足FC的路由条目才能放到EIGRP的拓扑表中，而只有拓扑表中有的FC才可以去实现负载均衡。
要实现负载均衡FC要满足两个条件：一是首先要成为可行继任者FC，即FC的AD<最优的FD。二是最优FD乘以variance>次优FD。
首先上图中的路径中R1-R3-R5是最优路径，这条路径的FD为20，而我们来比较剩余的两条路径的AD是不是满足可行继任者FC（次优的AD<最优的FD）。
路径R1-R2-R5的AD为10<20 ，满足FC，所以它也进入了拓朴表，做为备选路由.在不设置variance 时，如果主路由失效后，EIGRP会选择它装入路由表。
路径R1-R4-R5的AD为25大于20，不满足FC。所以这条路径不可能参加负载均衡。
这里variance 为3，20 X 3 为60 大于R1-R2-R5次优的FD 30,所以它参与负载均衡.因此选B。
第二题variance 为2, 20 X 2 为40 大于R1-R2-R5次优的FD 30,所以它参与负载均衡.因此选D
方法不一样