- Spanning-Tree Concepts
- Varieties of Spanning Tree Protocols
- Spanning-Tree Configuration
- First Hop Redundancy Protocols
This chapter is from the book
This chapter is from the book
This chapter is from the book
First Hop Redundancy Protocols
Up to this point, we’ve been reviewing STP and how to manipulate the election of root bridges and load balance across redundant links. In addition to Layer 1 and Layer 2 redundancy, a high-availability network might also implement Layer 3 redundancy by sharing the default gateway responsibility across multiple devices. Through the use of a virtual IP address, two Layer 3 devices can share the default gateway responsibility. The section reviews First Hop Redundancy Protocols (FHRPs) that provide Layer 3 redundancy.
Identify FHRP Terminology
Match the definition on the left with the terms on the right. This is a one-to-one matching exercise.
Definitions |
Terms |
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Identify the Type of FHRP
In Table 2-7, indicate whether the characteristic describes HSRP, VRRP, or GLBP.
Table 2-7 FHRP Characteristics
FHRP Characteristic |
HSRP |
VRRP |
GLBP |
Used in a group of routers for selecting an active device and a standby device. |
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A nonproprietary election protocol that allows several routers on a multi-access link to use the same virtual IPv4 address. |
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Cisco-proprietary FHRP protocol designed to allow for transparent failover of a first-hop IPv4 devices. |
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Cisco-proprietary FHRP protocol that protects data traffic from a failed router or circuit while also allowing load sharing between a group of redundant routers. |
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One router is elected as the virtual router master, with the other routers acting as backups in case the virtual router master fails. |
HSRP and GLBP Configuration and Verification
Refer to the topology in Figure 2-6. R2 has been configured for HSRP group 20, priority 120, IP address 192.168.1.20, and virtual IP address 192.168.1.1.
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Figure 2-6 HSRP and GLBP Configuration Topology
Example 2-1 shows the HSRP configuration for R2.
Example 2-1 R2 HSRP Configuration
R2# show run interface g0/1 <output omitted> interface GigabitEthernet0/1 ip address 192.168.1.20 255.255.255.0 standby 20 ip 192.168.1.1 standby 20 priority 120 <output omitted>
Using the information in Example 2-1, document the commands to configure R1 as the HSRP active router in group 20 using a priority of 210.
What command would generate the following output to verify the HSRP configuration?
R1#__________________
P indicates configured to preempt.
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Interface Grp Pri P State Active Standby Virtual IP
Gi0/1 20 210 Active local 192.168.1.20 192.168.1.1
Now assume that all HSRP configurations have been removed. R2 has been configured for GLBP group 20, priority 120, IP address 192.168.1.20, and virtual IP address 192.168.1.1.
Example 2-2 shows the GLBP configuration for R2.
Example 2-2 R2 GLBP Configuration
R2# show run interface g0/1 <output omitted> interface GigabitEthernet0/1 ip address 192.168.1.20 255.255.255.0 glbp 20 ip 192.168.1.1 glbp 20 priority 120 <output omitted>
Using the information in Example 2-2, document the commands to configure R1 to be in GLBP group 20 using a priority of 210.
What command would generate the following output to verify the GLBP configuration?
R1#__________________
GigabitEthernet0/0 - Group 20
State is Active
1 state change, last state change 00:03:05
Virtual IP address is 192.168.1.1
Hello time 3 sec, hold time 10 sec
Next hello sent in 1.792 secs
Redirect time 600 sec, forwarder timeout 14400 sec
Preemption disabled
Active is local
Standby is 192.168.1.20, priority 120 (expires in 9.024 sec)
Priority 210 (configured)
Weighting 100 (default 100), thresholds: lower 1, upper 100
Load balancing: round-robin
Group members:
0006.f671.db58 (192.168.1.10) local
0006.f671.eb38 (192.168.1.20)
There are 2 forwarders (1 active)
Forwarder 1
State is Active
1 state change, last state change 00:02:53
MAC address is 0007.b400.0a01 (default)
Owner ID is 0006.f671.db58
Redirection enabled
Preemption enabled, min delay 30 sec
Active is local, weighting 100
Forwarder 2
State is Listen
MAC address is 0007.b400.0a02 (learnt)
Owner ID is 0006.f671.eb38
Redirection enabled, 599.040 sec remaining (maximum 600 sec)
Time to live: 14399.040 sec (maximum 14400 sec)
Preemption enabled, min delay 30 sec
Active is 192.168.1.20 (primary), weighting 100 (expires in 9.312 sec)
Lab - Configuring HSRP and GLBP (SN 2.4.3.4/SwN 4.4.3.4)
