L2/L3 Etherchannel Flashcards
Learning all things L2/L3 Etherchannel for Cisco devices
What does PAgP standfor
Port AGgregation Protocol
What does LACP stand for?
Link Aggregation Control Protocol
What is the maximum number of links you can bundle in PAgP?
Max 8 Links
What is the maximum number of links you can bundle with LACP
As many as you want. However only 8 can be active at one time. All other links will be in standby mode.
Which Protocol is Cisco proprietary? LACP or PAgP?
PAgP
What IEEE standard was created for LACP? Both original and new.
802.3ad is the original and 802.1ax is the new standard.
Which Etherchannel dynamic protocol supports half duplex links?
PAgP, this is one of the benefits of this protocol. LACP does not support half duplex links.
What problems is solved by etherchannel?
-STP won’t block extra bandwidth/increased performance and link fault tolerance
Which Etherchannel dynamic protocol uses “On”?
Trick questions, “on” forces the etherchannel into an up state. Does not use a dynamic protocol. Would be susceptible to loops if etherchannel misconfiguration wasn’t enabled by default.
Which Etherchannel dynamic protocol uses Passive and Active? Describe these commands.
LACP. Passive will negotiate LACP if the other end is configured as Active. But will not act as the aggressor. Active acts as the aggressor and will try to establish LACP.
Active/Active or Active/Passive will work but passive/passive will not work.
Which Etherchannel dynamic protocol uses Auto and Desirable? Describe these commands.
PAgP. Auto will negotiate PagP if the other end is configured as desirable. But will not act as the aggressor. Desirable acts as the aggressor and will try to establish PAgP.
Desirable/Desirable or Desirable/Auto will work but Auto/Auto will not work.
What is the default priority of LACP ports?
32768 - since STP and LACP are both IEEE standards they correspond in this instance.
What is the default load-balance setting on L2 etherchannel?
Source MAC address - You can check this by using the “show etherchannel load-balance” command.
In L2 etherchannel, what configuration on the port channel and physical ports must be the same for it to work?
Speed Duplex Trunking Protocol Native vlan (for 802.1Q) Vlan permit list
In L3 etherchannel, what configuration on the port channel and physical ports must be the same for it to work?
Speed
Duplex
All must have “no switchport” command
What two parts make up an etherchannel?
Port-channel interface
- logical interface representing the link bundle
Member interfaces
- Physical links that are apart of the link bundle
A switch is connected to another switch running LACP. You preform the “Show etherchannel summary” command. You see the letter H next to one of you ports. Based on this information what is the minimum number of physical ports in the port channel?
9 - H is an etherchannel flag meaning a port is in hot-standby. This flag is only available for LACP. LACP can support up to 8 concurrent active ports in a port-channel every other interface after that is put into a Hot-standby mode.
*Remember, LACP is a priority based protocol for you to manage which ports will become active and which on will be standby you must configure the port priority . If you do not and everything is default priority of 32768, then the ports that will become active are the ones with the lowest port number. I.E. Port g1/0/1 has a higher priority than g1/0/2. Think Spanning-Tree.
Etherchannel Flags - What does D(Capital) stand for?
The etherchannel flag D represents Down
Etherchannel Flags - What does P(Capital) stand for?
The etherchannel flag P represents that the port is bundled in the port-channel.
Etherchannel Flags - What does U(Capital) stand for?
The etherchannel flag P represents the port is “in use”.
Etherchannel Flags - What does S(Capital) stand for?
The etherchannel flag S represents the Port channel is Layer 2
Etherchannel Flags - What does s(lower-case) stand for?
The etherchannel flag s represents that the port is suspended from the interface.
Etherchannel Flags - What does R(Capital) stand for?
The etherchannel flag R represents that the port channel is Layer 3
What syslog is generated whenever one of the Layer 2 etherchannel requirements is not met? (Same speed, duplex, native vlan.. etc)
Also what etherchannel flag will help indicate this?
%EC-5-CANNOT_BUNNLE2: is not compatible with and will be suspended ().
The etherchannel flag will be set to lower-case s for suspended.