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Difficulty: Very hardHigh Availability and Redundancy Concepts

Match each high availability or redundancy protocol/mechanism on the left with its precise operational characteristic or implementation detail on the right.

  • GLBP (Gateway Load Balancing Protocol)Elects an Active Virtual Gateway (AVG) to answer ARP requests for the virtual IP, distributing traffic across Active Virtual Forwarders (AVFs) using unique virtual MAC addresses.
  • LACP (Link Aggregation Control Protocol - IEEE 802.1AX)Exchanges protocol data units (LACPDUs) containing system priority and port keys to dynamically form multi-link trunk groups between switches.
  • Stateful Session SynchronizationReplicates dynamic connection state tables and NAT translations over a dedicated heartbeat link to prevent session drops during active/passive failover.
  • VRRP (Virtual Router Redundancy Protocol)An open-standard First Hop Redundancy Protocol that elects a Master router to serve the virtual IP using a standard virtual MAC address format of 00-00-5E-00-01-XX.

Answer

GLBP matches the mechanism utilizing an Active Virtual Gateway (AVG) to assign virtual MAC addresses to Active Virtual Forwarders (AVFs). LACP matches dynamic link bundling using LACPDUs with system priorities and operational keys. Stateful Session Synchronization matches replicating active connection and NAT tables across peer links. VRRP matches the open-standard FHRP employing virtual MAC addresses in the format 00-00-5E-00-01-XX.
GLBP uses an Active Virtual Gateway (AVG) to assign different virtual MAC addresses to Active Virtual Forwarders (AVFs) so multiple routers actively forward default gateway traffic. LACP automatically negotiates multi-link aggregation groups using LACPDUs and system priorities. Stateful Session Synchronization mirrors active connection tables across HA nodes so dynamic sessions survive failover without disconnecting users. VRRP is the open-standard FHRP that designates a Master router using the standardized IANA virtual MAC structure 00-00-5E-00-01-XX.

Step-by-Step Solution

1
Analyze GLBP operational mechanics
Identify that GLBP provides gateway load balancing by using an AVG to respond to ARP requests with distinct virtual MACs assigned to AVFs.
GLBP is unique among FHRPs because it active-active balances traffic across multiple gateways rather than operating purely in standby mode.
2
Analyze LACP link aggregation standards
Identify that LACP (IEEE 802.1AX / 802.3ad) uses LACPDUs, system IDs, port priorities, and keys to negotiate trunk formation.
LACP ensures both ends of an aggregated link agree on parameters prior to forwarding traffic.
3
Analyze stateful failover concepts
Identify that stateful session synchronization maintains active user sessions during device failover by replicating TCP state tables and NAT entries.
Without stateful synchronization, failover is stateless and requires hosts to re-establish existing TCP connections.
4
Analyze VRRP standards and addressing
Identify that VRRP is an open-standard protocol using the reserved virtual MAC range 00-00-5E-00-01-XX.
HSRP uses 0000.0c07.acXX (HSRPv1) or 0000.0c9f.fXXX (HSRPv2), whereas VRRP uses the IANA OID 00-00-5E-00-01-XX.

Key Concept

High Availability, Gateway Redundancy Protocols, and Link Aggregation Mechanics
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Topics

High Availability and Redundancy Concepts

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