Switch1 and Switch2 are configured as a VSS. Switch1 has a higher priority. Switch2 has a higher switch ID. Both switches are started simultaneously. Which of the following will occur if RRP discovers an incompatibility between the switches? (Select the best answer.)
A. Both switches will come up in RPR mode.
B. Both switches will come up in NSF/SSO mode.
C. Switch1 will come up in NSF/SSO mode, and Switch2 will come up in RPR mode.
D. Switch2 will come up in NSF/SSO mode, and Switch1 will come up in RPR mode.
Explanation:
Switch1 will come up in Nonstop Forwarding/StatefulSwitchover (NSF/SSO) mode, and Switch2 will come up in routeprocessor redundancy (RPR) mode. Virtual Switching System (VSS) combines two physical Cisco Catalyst switches into a single virtual switch with a unified control plane, which can result in greater network efficiency and bandwidth capacity. One switch chassis becomes the active virtual switch, and the other switch becomes the standby virtual switch. The switch chassis are connected together by a virtual switch link (VSL), which is implemented as an EtherChannel of up to eight physical interfaces. The standby chassis will monitor the VSL to ensure that the active chassis remains functional.
Configuration, monitoring, and troubleshooting must be performed on the active virtual switch? console access isdisabled on the standby virtual switch. The active virtual switch is responsible for all control plane functions, such as Simple Network Management Protocol (SNMP), Telnet, Secure Shell (SSH), Spanning Tree Protocol (STP), Link Aggregation Control Protocol (LACP), and Layer 3 routing. The data plane is active on both switches.
Virtual Switch Link Protocol (VSLP) is responsible for establishing the VSS. VSLP has two component protocols: Link Management Protocol (LMP) and Role Resolution Protocol (RRP). The VSS initialization process consists of the following steps:
1. The configuration file is pre-parsed for VSL configuration commands.
2. The VSL member interfaces are brought online.
3. LMP verifies link integrity, rejects unidirectional links, and establishes bidirectional communication between switch chassis.
4. LMP exchanges switch IDs in order to detect duplicate IDs.
5. RRP checks hardware versions, software versions, and VSL configurations for compatibility.
6. RRP assigns the active virtual and standby virtual switch roles.
7. Switches come up in NSF/SSO mode or RPR mode.
8. Switches continue the normal boot process.
The switch chassis that is started first will always become the active virtual switch unless preemption is configured. If both chassis are started simultaneously, the switch with the highest priority will become the active virtual switch. By default, the priority is set to a value of 100. If priorities are equal, the switch with the lower switch ID will become the active virtual switch. In this scenario, Switch1 has a higher priority and a lower switch ID; therefore, Switch1 will become the active virtual switch and Switch2 will become the standby virtual switch. If the active chassis fails and subsequently recovers, it will assume the role of standby chassis unless preemption is configured.
If RRP determines that both switches are compatible, both chassis will come up in NSF/SSO mode, in which all modules are powered up and can forward traffic. If RRP determines that an incompatibility exists, the standby virtual switch will come up in RPR mode, in which all modules are powered down. In this scenario, Switch1 will come up in NSF/SSO mode and Switch2 will come up in RPR mode.