EtherChannel

Question 0

What is the benefit of having multiple links between devices?

Answer 0

Redundancy and increased bandwidth.

Question 1

What is the function of EtherChannel?

Answer 1

It groups several physical ports into one logical channel. (One benefit of this grouping is that STP won’t block any of these ports in the interest of preventing loops - this way you can have multiple links in use between two layer 2 or layer 3 devices)

Question 2

What are the two protocols that can be used to configure EtherChannel?

Answer 2

PAgP - Cisco proprietary

LACP - 802.3ad IEEE standard

Question 3

In PAgP, what are the two port channel modes and what do they do?

Answer 3

Desirable - configures port to ask other side if it can or will participate in EtherChannel

Auto - configures port to wait for other side to determine port channel status

Question 4

In LACP, what are the two modes and what do they do?

Answer 4

Active - actively asks whether other side can or will participate

Passive - waits for other side to initiate negotiation

Question 5

All interfaces within an EtherChannel must have the same configuration for what four things?

Answer 5

1. Speed and duplex
2. Mode (access port or trunk port)
3. Native and allowed VLANs on
   trunk ports
4. Access VLAN on access ports

Question 6

What are the commands you would use to configure EtherChannel?

Answer 6

Create bundle:

interface range (FastEthernet 0/1 - 2)

channel-group 1 mode (on/active/passive/desirable/auto)

exit

Configure as trunk or access port:

interface port-channel 1

switchport mode (trunk/access)

if trunk:

switchport trunk allowed VLAN (desired allowed VLAN #’s, comma delineated)

Question 7

What are the commands you can use to verify EtherChannel configuration?

Answer 7

show interface port-channel 1 (or whatever port channel you’ve created)

show EtherChannel summary: summary per channel group

show EtherChannel port-channel:
shows port channel info