CCNP Exam Prep Tips and Must Knows

studyTestExamThings You Need to Know about Link Aggregation with EtherChannel

EtherChannel

  • Solution to provide more bandwidth
  • Logical aggregation of similar links
  • Provides load balancing and redundancy
  • Supported for switch ports routed ports

PAgP and LACP

  • Protocols to negotiate the EtherChannel link
  • PAgP is Cisco proprietary
  • LACP is IEEE  802.3ad standard
  • Static EtherChannel configuration without protocol

PAgP Mode

  • On: Channel member without negotiation (no protocol)
  • Desirable: Actively ask if the other side can/will become an EtherChannel
  • Auto: Passively wait for the other side to ask
  • Off: EtherChannel not configured on interface

LACP Mode

  • On: Channel number without negotiation (no protocol)
  • Active: Actively asked if the other side can/will become an EtherChannel ARP
  • Passive: Passively wait for other side to ask
  • Off: EtherChannel not configured on interface

All interfaces within an EtherChannel must have same attributes:

  • Same speed and duplex
  • Same mode (access or trunk)
  • Same native and allowed VLANS on trunk ports
  • Same access VLAN on access ports
  • Same MTU size
  • Configure parameters on port-channel interface

 

Make sure you can configure:

  • LACP
  • PAgP
  • Statically configured EtherChannel  

Know how to:

  • Identify which protocol is being used to form EtherChannel

Make sure you are familiar with output:

  • Show etherchannel summary
  • Show etherchannel
  • Show interface [  ] etherchannel
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1 comment

  1. Boutara Noureddine Reply

    Thanks