排错300-135的case 1 第三个问题,求助

gbcbooks

Case1
A customer network engineer has made configuration changes that have
resulted in some loss of connectivity. You have been called in to evaluate a
switch network and suggest resolutions to the problems.



QUESTION 3
You have configured PVST+ load balancing between SW1 and the
New_Switch in such a way that both the links E2/2 and E2/3 are utilized for
traffic flow, which component of the configuration is preventing PVST+ load
balancing between SW1 and SW2 links
A. Port priority configuration on SW1
B. Port priority configuration on the New_Switch
C. Path cost configuration on SW1
D. Path cost configuration on the New_Switch
Correct Answer: D
Section: Case
Explanation
Explanation/Reference:
Here is the configuration found on the New_Switch:


This causes the port cost for link eth 1/3 to increase the path cost to 250 for all
VLANs, making that link less preferred so that only eth 1/2 will be used.



这题讲的。load-balancing是哪种方式的？

chengxu410

这么说吧.PVST+允许每个VLAN运行一个STP进程。每个STP进程会根据Cost和优先级等参数确定，某个交换机的某个接口为根端口，指定端口，或非指定端口。以本题为例打个比方，假设负载均衡需要在VLan100中流量走eth1/2,在Vlan1和其他Vlan中流量走eth1/3。本题人为提高了eth1/3的cost，使它在选举根端口或指定端口始终处在劣势，最后被选为非指定端口，处于BLK状态无法转发流量，自然也就无法实现负载均衡。Cost和priority是很灵活的参数。

gbcbooks

chengxu410 发表于 2015-3-4 17:35
这么说吧.PVST+允许每个VLAN运行一个STP进程。每个STP进程会根据Cost和优先级等参数确定，某个交换机的某个 ...

哦，对哦。谢谢