In the last article we listed 100 interview questions for network engineers. May be some of them are not often asked. Again, here we gathered most frequently asked interview questions for network engineers in most of the multinational companies in India.
- What is the use of HSRP? …
- What is the maximum number of HSRP groups can be created in the router? …
- What is the HSRP virtual MAC address. …
- What are the maximum number of routers can be present in a group? …
- HSRP uses TCP or UDP?
In case of single vlan in lan, HSRP provides Redundancy OR, Load sharing OR, both ?
What is the effect of Tracking and what is the default value of decrement in case of failure of a single interface?
In case of multiple vlan in lan, HSRP provides Redundancy OR, Load sharing OR, both ?
Maximum no. of HSRP Groups = 16 Maximum no. of Layer 3 devices or members in a single HSRP group = 16 Total no. of Layer 3 devices = 16 X 16 = 256
Basic Configuration of HSRP – VRRP – GLBP
Before moving into our comparison between the 3 protocols, let’s first see the basic configuration for each one:
R1
interface Ethernet0/1 description LAN Interface of Active Router ip address 192.168.1.1 255.255.255.0 standby 1 ip 192.168.1.254 <—- Create HSRP Group 1 and assign Virtual IP standby 1 priority 101 <—- Assign priority above 100 to make this the primary router standby 1 preempt <—- Makes router active if it has higher priority
R2
interface Ethernet0/1 description LAN Interface of Standby Router ip address 192.168.1.2 255.255.255.0 standby 1 ip 192.168.1.254 <—- Create HSRP Group 1 and assign Virtual IP standby 1 preempt <—- Makes router active if it has higher priority
R1
interface Ethernet0/1 description LAN Interface of Active Router ip address 192.168.1.1 255.255.255.0 vrrp 1 ip 192.168.1.254 <—- Create VRRP Group 1 and assign Virtual IP vrrp 1 priority 101 <—- Assign priority above 100 to make this the primary router vrrp 1 preempt <—- Makes router active if it has higher priority
R2
interface Ethernet0/1 description LAN Interface of Standby Router ip address 192.168.1.2 255.255.255.0 vrrp 1 ip 192.168.1.254 <—- Create VRRP Group 1 and assign Virtual IP vrrp 1 preempt <—- Makes router active if it has higher priority
R1
interface Ethernet0/1 description LAN Interface of Primary Router ip address 192.168.1.1 255.255.255.0 glbp 1 ip 192.168.1.254 <—- Create GLBP Group 1 and assign Virtual IP glbp 1 priority 101 <—- Assign priority above 100 to make this the primary router glbp 1 preempt <—- Makes router active if it has higher priority glbp 1 load-balancing round-robin <—- Configure round-robin balancing of traffic
R2
interface Ethernet0/1 description LAN Interface of Secondary Router ip address 192.168.1.2 255.255.255.0 glbp 1 ip 192.168.1.254 <—- Create GLBP Group 1 and assign Virtual IP glbp 1 preempt <—- Makes router active if it has higher priority glbp 1 load-balancing round-robin <—- Configure round-robin balancing of traffic
HSRP Versus VRRP Comparison Table
| HSRP | VRRP |
| Propietary | Standards based |
| RFC 2281 | RFC 3768 |
| Separate IP Address needed for the Virtual | Can use the physical IP Address of the Virtual, if needed, saving IP space. |
| One Master, One Standby, all others are listening | One Master, all other routers are backup |
| More familiar to most network engineers | Less familiar – yet very similar |
| Can track an interface for failover | Can track an interface for failover (depending on operating system and version, it can also track the reachability of an IP address) |
| All HSRP routers use multicast hello packets to 224.0.0.2 (all routers) for version 1 or 224.0.0.102 for version 2. | All VRRP routers use IP protcol number 112 (vrrp) to communicate via multicast IP address 224.0.0.18 |
| All virtual router must use MAC address 0000.0c07.acXX where XX is the group ID. | All virtual routers must use 00-00-5E-00-01-XX as its Media Access Control (MAC) address |
Configuration differences in HSRP vs VRRP
The differences between both VRRP and HSRP, especially on a Cisco router are very slight. If your familiar with Configuring HSRP you can easily understand VRRP commands. Configuring VRRP on Juniper as well as other network equipment can vary significantly depending on the devices. Many load balancers also support VRRP and their configuration is specific to each of these devices.
Here are some configuration examples as seen on a Cisco router:
FAQ
What is HSRP and VRRP?
What is the difference between HSRP VRRP and Glbp?
What is the purpose of HSRP protocol?
