352-001 · Question #88
Tesla Radio GmbH is going to build a new research lab network based on a set of switches that would connect to their existing enterprise network. They are considering a design that would guarantee…
The correct answer is C. IEEE 802.1s. IEEE 802.1s (MSTP) satisfies both requirements by providing loop-free operation and allowing a group of switches in an MST region to appear as a single virtual bridge to external networks.
Question
Tesla Radio GmbH is going to build a new research lab network based on a set of switches that would connect to their existing enterprise network. They are considering a design that would guarantee loop-free behavior within the set of switches. The design would also allow the group of switches to seem like a single switch to the enterprise network, because it is owned by a separate administrative group. Which Spanning Tree Protocol should be used to support the design requirements?
Options
- AIEEE 802.1w
- BIEEE 802.1D
- CIEEE 802.1s
- DIEEE 802.1p
How the community answered
(31 responses)- A6% (2)
- B13% (4)
- C77% (24)
- D3% (1)
Why each option
IEEE 802.1s (MSTP) satisfies both requirements by providing loop-free operation and allowing a group of switches in an MST region to appear as a single virtual bridge to external networks.
IEEE 802.1w (RSTP) improves convergence speed but does not define MST regions or any mechanism for a group of switches to appear as a single logical entity to an external network.
IEEE 802.1D (classic STP) provides basic loop prevention but has no region concept, no instance support, and uses slow 30-50 second convergence timers.
802.1s introduces the MST region concept, where switches sharing an identical MST configuration (region name, revision number, and VLAN-to-instance mapping) are treated as a single logical STP entity by switches outside the region. This lets the research lab's switch group maintain internal loop-free behavior while presenting one virtual bridge to the enterprise network, satisfying the separate administrative ownership requirement.
IEEE 802.1p defines Layer 2 class-of-service priority markings in Ethernet frame headers and has no relationship to spanning tree or loop prevention.
Concept tested: MSTP region design for administrative boundary isolation
Source: https://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/24248-147.html
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