Which two are effects of connecting a network segment that is running 802.1D to a network segment that is running 802.1w? (Choose Two.)

Question

Options

• Athe entire network switches to 802.1D and generates BPDUs to determine root bridfe status.
• BA migration delay of three seconds occurs when the port that is connected to the 802.1D bridge
• CThe entire network reconverges and a unique root briddge for the 802.1D segment, and a root bridge
• Dthe first hop 802.1w switch that is connected to the 802.1D runs entirely in 802.1D compatibility mode
• EClassic 802.1D timers, Such as forward Delay and Max-age, will only be used as a backup, and will

• A
  10% (5)
• B
  82% (41)
• C
  4% (2)
• D
  4% (2)

Explanation

Each port maintains a variable that defines the protocol to run on the corresponding segment. A migration delay timer of three seconds also starts when the port comes up. When this timer runs, the current STP or RSTP mode associated to the port is locked. As soon as the migration delay expires, the port adapts to the mode that corresponds to the next BPDU it receives. If the port changes its mode of operation as a result of a BPDU received, the migration delay restarts. 802.1D works by the concept that the protocol had to wait for the network to converge before it transitioned a port into the forwarding state. With Rapid Spanning Tree it does not have to rely on any timers, the only variables that that it relies on is edge ports and link types. Any uplink port that has an alternate port to the root can be directly placed into the forwarding state (This is the Rapid convergence that you speak of "restored quickly when RSTP is already in use?"). This is what happened when you disconnected the primary look; the port that was ALT, moved to FWD immediately, but the switch also still needs to create a BDU with the TC bit set to notify the rest of the network that a topology has occurred and all non-edge designated ports will transition to BLK, LRN, and then FWD to ensure there are no loops in the rest of the network. This is why if you have a host on a switchport, and you know for a fact that it is only one host, enable portfast to configure the port as an edgeport so that it does not have to transition to all the STP states.

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