Practice Q's - VRRP Flashcards
What command would be used to display detailed information regarding VRRP groups on the switch?
A. switch# show vrrp
B. switch# show standby
C. switch# show vrrp detail
D. switch# show standby detail
Answer: A
Explanation:
The command that would display detailed information regarding VRRP groups on the switch is show vrrp. The information provided for each VRRP group by this command includes the status, virtual IP and MAC addresses, whether preemption is enabled, priority of the switch, and the address of the group master.
The command show vrrp detail does not exist on a Cisco device. The detail view is provided by the command show vrrp.
The command show standby can be used to display detailed information about HSRP groups to which a switch belongs. This command is for HSRP only.
The command show standby detail provides the same output as show standby. It can be used to display detailed information about HSRP groups a switch is a member of. This command is for HSRP only.
Which next-hop router redundancy protocol provides backup for an assigned real IP address?
A. HSRP
B. GLBP
C. VRRP
D. CGMP
Answer: C
Explanation:
Using VRRP, the shared address of the next-hop router redundancy group can be the real address of a router interface.
Virtual Router Redundancy Protocol (VRRP) is defined in RFC 2338. VRRP enables a group of routers to form a single virtual router, known as a VRRP group. Routers are configured in VRRP groups to provide redundancy for an IP address shared among members of the VRRP group.
This address can be the real address of a router interface or a virtual address (or addresses) shared by the group. Each group is comprised of a master and one or more backup routers. If the shared address is the real IP address of a router, that router will always be the master when the address is available.
The master router is responsible for forwarding packets sent to the virtual router. The backup routers provide redundancy and stand ready to assume the role of the master router in the event that it is unable to forward packets.
The master virtual router owns the VRRP IP address and is responsible for handling all packets sent to the VRRP IP address. Backup VRRP routers monitor for hello activity from the master virtual router. The master router will advertise using IP 224.0.0.18 and MAC 0000.0c00.01xx (xx is the VRRP Group ID). The advertisements by default will be sent every second, and the master down interval is three seconds.
If the VRRP IP address is NOT the physical address of one of the VRRP routers, then the router with the highest priority will assume the role of the master. The configurable priority range is from 0 to 255, and the default value is 100. The higher the value is, the higher the priority is.
If activity stops for the duration of the master router’s down interval, the backup router with the highest priority will become the master router. When the old master router comes back online, it will assume the master role again if it still has the highest priority among all routers.
In the configuration shown below, Router A will be the master router unless it goes down, in which case B will take over. If A comes back up it will assume the master role again.
- routerA(config-if)# vrrp 3 priority 130
- routerB(config-if)# vrrp 3 priority 110
Hot Standby Router Protocol (HSRP) defines a set of routers that work together to represent one virtual, fault-tolerant router. Thus, redundancy is provided in the event that any one of the routers fails. The shared address of the next-hop router redundancy group is not the real address of a router interface.
Gateway Load Balancing Protocol GLBP) is a Cisco-designed protocol that provides for the dynamic utilization of redundant routers in a broadcast network. The shared address of the nexthop router redundancy group is not the real address of a router interface. A virtual group address is used.
What command provides the output shown below?
A. switch# show vrrp brief
B. switch# show standby
C. switch# show glbp
D. switch# show vrrp
Answer: D
Explanation:
The command that displays the output in the exhibit is show vrrp. This command displays detailed information regarding VRRP groups on the switch. The information provided for each VRRP group by this command includes the status, virtual IP and MAC addresses, whether preemption is enabled, priority of the switch, and the address of the group master.
The command show vrrp brief is used to display a summary of the VRRP groups to which the switch belongs. The summary information it provides includes the group number, priority, state, whether preemption is enabled, the Master IP address, and the group IP address.
The command show glbp displays detailed information about GLBP groups on the switch. This information includes the GLBP groups the switch is a member of, whether this is the active switch, the virtual IP address, and whether preemption is enabled.
The command show standby can be used to display detailed information about HSRP groups to which a switch belongs. This command displays information about HSRP on all configured interfaces and for all HSRP groups. This command is for HSRP only.
You need to create an implementation plan for providing Layer 3 redundancy in your switched network. You included Hot Standby Routing Protocol (HSRP) as the protocol to avoid first-hop router failure. However, your supervisor suggests including Virtual Router Redundancy Protocol (VRRP) instead of HSRP in the implementation plan.
Which of the following statements is TRUE about the reasons for the suggested change in the implementation plan? (Choose two.)
A. HSRP works only on Cisco routers and VRRP works on both Cisco and non- Cisco routers.
B. HSRP works on both Cisco and non-Cisco routers and VRRP works only Cisco routers.
C. HSRP-enabled routers need to be configured manually to preempt the active router and VRRPenabled routers preempt it automatically.
D. HSRP-enabled routers automatically preempt the active router and VRRP-enabled routers need to be configured manually to preempt the active router.
Answer: A,C
Explanation:
The following two statements are TRUE:
HSRP was developed by Cisco intended for only Cisco routers and VRRP was developed by IEFT intended as a standard for routers. HSRP was defined in RFC 2281 and VRRP was defined in RFC 2338. Both these protocols provide a fault tolerance solution by grouping several routers together but presenting them as a single router.
One of the routers in the group acts as the active or master router. A second router is selected as the standby router. In case the active or master router fails, the standby router takes over the responsibilities of the active router.
The router with the highest priority is automatically selected as the active or master router. In HSRP, preempt settings have to be manually configured on every router in the group, even if the routers have a priority higher than that of the active router. However, in VRRP, the routers with higher priority automatically preempt the master router. Another advantage that VRRP has over HSRP is a faster Hello timer (1 second). HSRP has a Hello timer of 3 seconds
Two other protocols ICMP Router Discovery Protocol (IRDP) and Gateway Load Balancing Protocol (GLBP) provide redundancy for first-hop router failure. IRDP also allows the selection of a new router if the active router fails, while GLBP provides load balancing in addition to redundancy.
Which routers comprise a VRRP group?
A. Host and client
B. Master and backup
C. Active and standby
D. Primary and secondary
Answer: B
Explanation:
Virtual Router Redundancy Protocol (VRRP) enables a group of routers to form a single virtual router, known as a VRRP group. Routers are configured in VRRP groups to provide redundancy for a virtual IP address shared among members of the VRRP group.
Each group is comprised of a master router and one or more backup routers. The physical IP address of the master router will be the virtual IP address of the group.
The master router is responsible for forwarding packets sent to the virtual router. The backup routers provide redundancy and stand ready to assume the role of the master router in the event that the master is unable to forward packets.
Which First Hop Redundancy Protocol is an IEEE Standard?
A. GLBP
B. HSRP
C. VRRP
D. OSPF
Answer: C
Explanation:
A comparison of the three First Hop Redundancy Protocols are listed below:
ProtocolFeatures
HSRP
(Hot Standby Router protocol)
VRRP
(Virtual Redundancy Router Protocol)
GLBP
(Gateway Load Balancing Protocol)
Router role
- 1 active router.- 1 standby router.- 1 or more listening routers.
- 1 master router.- 1 or more backup routers.
- 1 AVG (Active Virtual Gateway).- up to 4 AVF routers on the group (Active Virtual Forwarder)
passing traffic.- up to 1024 virtual routers (GLBP groups) per physical interface.
- Use virtual ip address.
- Can use real router ip address, if not, the one with highest priority become master.
- Use virtual ip address.
Scope
Cisco proprietary
IEEE standard
Cisco proprietary
Election
Active Router:1-Highest Priority2-Highest IP (tiebreaker)
Master Router: (*)1-Highest Priority2-Highest IP (tiebreaker)
Active Virtual Gateway:1-Highest Priority2-Highest IP (tiebreaker)
Optimization features
Tracking
yes
yes
yes
Preempt
yes
yes
yes
Timer adjustments
yes
yes
yes
Traffic type
- 0.0.2 – udp 1985 (version1)224.0.0.102-udp 1985 (version2)
- 0.0.18 – IP 112
- 0.0.102 udp 3222
Timers
Hello – 3 seconds
Advertisement – 1 second
Hello – 3 seconds
(Hold) 10 seconds
(Master Down Interval)3 * Advertisement + skew time
(Hold) 10 seconds
(Skew time)(256-priority) / 256
Load-balancing functionality
- Multiple HSRP group per interface/SVI/routed int.
- Multiple VRRP group per interface/SVI/routed int.
Load-balancing oriented- Weighted algorithm.- Host-dependent algorithm.
- Round-Robin algorithm (default).
Requires appropriate distribution of Virtual GW IP per Clients for optimal load-balancing.(generally
through DHCP)
Requires appropriate distribution of Virtual GW IP per Clients for optimal load-balancing.(generally
through DHCP)
Clients are transparently updated with virtual MAC according to load-balancing algorithm through
ARP requesting a unique virtual gateway.
Reference: http://cciethebeginning.wordpress.com/2008/08/23/router-high-availability-protocolcomparison-
2/
Which VRRP router is responsible for forwarding packets that are sent to the IP addresses of the virtual router?
A. virtual router master
B. virtual router backup
C. virtual router active
D. virtual router standby
Answer: A
Explanation:
VRRP Definitions
VRRP Router A router running the Virtual Router Redundancy
Protocol. It may participate in one or more
virtual routers.
Virtual Router An abstract object managed by VRRP that acts
as a default router for hosts on a shared LAN.
It consists of a Virtual Router Identifier and
a set of associated IP address(es) across a
common LAN. A VRRP Router may backup one or
more virtual routers.
IP Address Owner The VRRP router that has the virtual router’s
IP address(es) as real interface address(es’.
This is the router that, when up, will respond
to packets addressed to one of these IP
addresses for ICMP pings, TCP connections,
etc.
Primary IP Address An IP address selected from the set of real
interface addresses. One possible selection
algorithm is to always select the first
address. VRRP advertisements are always sent
using the primary IP address as the source of
the IP packet.
Virtual Router Master The VRRP router that is assuming the
responsibility of forwarding packets sent to
the IP address(es) associated with the virtual
router, and answering ARP requests for these
IP addresses.Note that if the IP address
owner is available, then it will always become
the Master.
Which protocol will enable a group of routers to form a single virtual router and will use the real IP address of a router as the gateway address?
A. Proxy ARP
B. HSRP
C. IRDP
D. VRRP
E. GLBP
Answer: D
