CCNP Switch 300-115 Study Guide – EtherChannels

I recently sat my CCNP 300-115 – Switch exam. I spent months taking notes on all of the important information needed to pass the exam. This study guide focuses on all things related to Etherchannels.

Please see other CCNP Switch Sudy Guides

EherChannels

  • When a physical switch port is part of an EtherChannel group. What happens when the same port is configured as a span destination – The operation is not allowed
  • Two combinations of EtherChannel modes support the formation of an EtherChannel. Desirable/desirable, active/passive
  • An EtherChannel has been established between a switch and webserver. An admin notices only one link is being over utilised. What should be done. To resolve you must adjust the EtherChannel load balancing method based on source Ip addresses.
  • By default, when an LACP channel is configured, the LACP channel mode is on
  • If EtherChannel detects a misconfiguration on a connected device – the port gets put in a error disabled mode.
  • When a channel group interface is configured as a SPAN destination, the interface is removed from channel group.
  • LACP – Passive, Active
  • LACP components used to determine which hot standby links become active – LACP system priority, LACP port priority, System ID, Port number
  • PAgP modes are off, auto, desirable and on. Only combinations auto-desirable, desirable-desirable, and on-on allow the formation of an Etherchannel.
  • If you change the port speed and duplex of an existing EtherChannel, PAgP changes the port speed and duplex on all ports in the bundle.
  • A Cisco switch can support up to 8 Ethernet interfaces, bandwidth of up to 800mbs on fast Ethernet and 8gbps on gigabit
  • LACP – open standard protocol
  • PAgP – Cisco proprietary protocol
  • mLACP – multichasis LACP – converting port chanel to mLACP can cause service disruption
  • Auto – PAgP mode that receives and responds without initiating EtherChannel
  • PAgP states that will form EtherChannel – desirable / Auto
  • When a layer 2 EtherChannel is configured, the IP address is placed on the port channel logical interface.
  • When EtherChannel guard is enabled and a  misconfiguration is detected the port enters the errdisable state.
  • Two operations attributes should be checked for EtherChannel ports that are in errdisable state – duplex, VLAN
  • LACP priority is used to determine which port is put in standby mode.
  • Default mode for LACP EtherChannel – Passive
  • For an EtherChannel to operate at layer 3 – configure EtherChannel directly on interface and configure the no switchport command on physical interfaces.
  • Layer 2 EtherChannel the IP address is placed on the port Chanel logical interface.
  • When storm control is configured on EtherChannel it is applied to the Cbundle and all associated physical interfaces.
  • Command- spanning-tree EtherChannel guard misconfig (configure globally) 
  • PAgP helps in the automatic creation of a fast EtherChannel and does not group ports configured for dynamic VLANs
  • Which 2 operational attributes can be checked for EtherChannel that are in err disable state – VLAN, Port mode.
  • A physical switch port is part of an EtherChannel. What happens while the same is configured as a span destination – The port is removed from the EtherChannel.
  • Where should layer 3 Etherchanel be used if needed – In the network distribution layer

LACP components used to determine which hot standby links become active after interface failure within etherchanel bundle

  • LACP System Priority
  • System port priority
  • System ID
  • Port number

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