Last Updated on August 1, 2021 by Admin 2
Which statement best describes the interaction between a workstation and an HSRP virtual router?
- The workstation must have the real IP address of one of the HSRP routers defined as its default gateway.
- The workstation must support IRDP in order to switch to the alternate router in an HSRP group.
- The active HSRP router replies to the workstation’s ARP request with the virtual router’s MAC address.
- The workstation sends packets to the active router’s real MAC address.
The active HSRP router replies to the workstation’s ARP request with the HSRP virtual MAC address. The HSRP virtual router presents a consistently available router to the end user, reachable by a single unique, virtual MAC address. Only the active router responds to frames destined to this virtual MAC address, which identifies the HSRP group.
The primary function of HSRP is to define a set of routers that work together to represent one virtual, fault-tolerant router. Thus, redundancy is provided in the event that one of the routers fails. An HSRP group consists of an active router and a standby router, which together present the appearance of a virtual router. The active router is elected from the routers configured to belong to the HSRP group. The virtual router’s MAC address identifies the virtual router, and the end user will send packets to that destination MAC address. The end-user device will send an ARP request using the known IP address of its default gateway to discover the virtual router’s MAC address. Only the active router will respond to the ARP request. The active router will then forward packets sent to the virtual router. The standby router monitors the status of the HSRP group and assumes packet-forwarding responsibilities of the virtual router if the active router fails.
The six HSRP states are defined as follows:
- Initial state: All routers start in this state.
- Learn state: The router is in the learn state when it has not communicated with the active router. It does not know which router is the active router and does not know the IP address of the virtual router (if no HSRP IP address configured in the router).
- Listen state: Once the router hears from the active router and knows the virtual IP address, it enters the listen state. It is not the active or standby router.
- Speak state: After a router learns the IP address of the virtual router, it enters the speak state. It participates in the active and standby router election. It sends hello messages to the active router.
- Standby state: When the active router has been elected, the second router enters the standby state. This is the standby router and it will become the active router if the active router fails.
Active state: The router is in active state when it is forwarding packets. It receives packets via the virtual IP address.
Neither the workstation nor any other device is required to support ICMP Router Discovery Protocol (IRDP) in order to implement an HSRP virtual router. An IRDP-compliant device (RFC 1256) listens for IRDP hello messages, which advertise default routes.
It is not required for the workstation to know the actual IP address of any of the routers in the group. The end-user device will send an ARP request using the known IP address of its default gateway to discover the virtual router’s MAC address.
The workstation does not send packets to the active router’s real MAC address. It will send packets to virtual router’s MAC address.
Configure and verify first-hop redundancy protocols