Cisco 300-115 Exam Dumps

300-115 Question 4

Refer to the exhibit.

Which set of configurations will result in all ports on both switches successfully bundling into an EtherChannel?


A. switch1
   channel-group 1 mode active
   switch2
   channel-group 1 mode auto
B. switch1
   channel-group 1 mode desirable
   switch2
   channel-group 1 mode passive
C. switch1
   channel-group 1 mode on
   switch2
   channel-group 1 mode auto
D. switch1
   channel-group 1 mode desirable
   switch2
   channel-group 1 mode auto


Correct Answer: D
Explanation/Reference:
The different etherchannel modes are described in the table below:
Mode Description
active Places an interface into an active negotiating state, in which the interface starts negotiations with other interfaces b y sending LACP packets.
auto Places an interface into a passive negotiating state, in which the interface re- sponds to PAgP packets it receives but do es not start PAgP packet negotia- tion. This setting minimizes the transmission of PAgP packets.
desirable Places an interface into an active negotiating state, in which the interface starts negotiations with other interface s by sending PAgP packets. on Forces the interface into an EtherChannel without PAgP or LACP. With the on mode, a usable EtherChannel exists only when an  interface group in the on mode is connected to another interface group in the on mode.
passive Places an interface into a passive negotiating state, in which the interface re- sponds to LACP packets that it receive s, but does not start LACP packet ne- gotiation. This setting minimizes the transmission of LACP packets.
Both the auto and desirable PAgP modes allow interfaces to negotiate with partner interfaces to determine if they can form an E therChannel based on criteria such as interface speed and, for Layer 2 EtherChannels, trunking state and VLAN numbers.
Interfaces can form an EtherChannel when they are in different PAgP modes as long as the modes are compatible. For example:
 . An interface in the desirable mode can form an EtherChannel with another interface that is in the desirable or auto mode.
 . An interface in the auto mode can form an EtherChannel with another interface in the desirable mode.
An interface in the auto mode cannot form an EtherChannel with another interface that is also in the auto mode because neither  interface starts PAgP negotiation. An interface in the on mode that is added to a port channel is forced to have the same characteristics as the already existing  on mode interfaces in the channel.
Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3550/software/release/12- 1_13_ea1/configuration/guide/355 0scg/swethchl.html