3.5 First Hop Redundancy Protocols Flashcards
Summarize the purpose, functions, and concepts of first hop redundancy protocols. (24 cards)
What is the primary purpose of First Hop Redundancy Protocols (FHRP)?
To ensure default gateway redundancy.
FHRP allows seamless failover between routers, preventing disruptions if the primary gateway fails.
Why is FHRP important in enterprise networks?
It eliminates single points of failure.
Without FHRP, gateway failure could disconnect all devices in a subnet from external networks.
How does FHRP ensure high availability?
By assigning a virtual IP to multiple routers.
A standby router assumes gateway duties if the active one fails.
Define:
Hot Standby Router Protocol
(HSRP)
A Cisco protocol for gateway failover.
HSRP elects an active and standby router using priority values.
What are the three main FHRPs?
- HSRP
- VRRP
- GLBP
HSRP (Hot Standby Router Protocol): Cisco protocol with active/standby routers.
VRRP (Virtual Router Redundancy Protocol): Open-standard with a master router.
GLBP (Gateway Load Balancing Protocol): Cisco protocol with load balancing.
True or False:
VRRP is a Cisco proprietary protocol.
False
VRRP (Virtual Router Redundancy Protocol) is an open standard, while HSRP is Cisco-specific.
What metric does HSRP use to determine the active router?
Priority value
The router with the highest priority becomes active; default is 100.
Why is preemption important in HSRP?
It restores priority-based leadership.
If a higher-priority router recovers, preemption ensures it resumes its active role, maintaining network efficiency.
How does VRRP election work?
The highest-priority router becomes master.
Unlike HSRP, VRRP elects a master instead of an active router and can be used with non-Cisco devices.
Define:
Gateway Load Balancing Protocol
(GLBP)
A Cisco protocol balancing traffic.
GLBP enables multiple active routers, unlike HSRP and VRRP, improving redundancy and load distribution.
List three HSRP (Hot Standby Router Protocol) states.
- Active
- Standby
- Listen
Active: The primary router forwarding traffic.
Standby: The backup router ready to take over.
Listen: Other routers monitoring but not forwarding.
True or False:
GLBP allows multiple active gateways.
True
Unlike HSRP and VRRP, GLBP actively balances traffic across multiple routers.
Fill in the blank:
The VRRP equivalent of an active router is ______.
master
VRRP uses the term “master” instead of “active,” designating the primary router for traffic forwarding.
What is the default HSRP priority?
100
A higher priority increases the likelihood of being elected as the active router.
How does GLBP improve redundancy over HSRP and VRRP?
By enabling active-active routers.
Unlike HSRP and VRRP, which rely on a single active router, GLBP distributes network traffic for load balancing.
What are the HSRP versions?
- Version 1
- Version 2
Version 1: Uses IPv4 multicast 224.0.0.2 and supports fewer groups.
Version 2: Supports larger group numbers and IPv6.
Fill in the blank:
The MAC address of an HSRP group starts with ______.
0000.0C07.ACxx
This Cisco-specific MAC address format uniquely identifies HSRP groups.
What protocol number does VRRP use?
112
VRRP is assigned protocol number 112 by IANA, distinguishing it from other redundancy protocols.
Why is authentication important in FHRP?
It prevents unauthorized router control.
Authentication mechanisms ensure only trusted routers participate in FHRP operations, preventing network attacks.
Define:
GLBP weighting
A traffic distribution method.
Weight values determine how much traffic each router handles, allowing flexible load balancing.
What is the main VRRP packet type?
Advertisement
The master router sends advertisement messages to indicate its presence and maintain redundancy.
True or False:
VRRP supports up to 255 virtual routers per group.
True
VRRP’s scalability supports larger networks by accommodating more virtual routers.
What is the default HSRP hello interval?
3 seconds
This interval can be modified to speed up failover response times.
Why is multicast used in FHRP communication?
It reduces overhead.
HSRP and VRRP use multicast to efficiently distribute redundancy information across participating routers.
