4.13 To construct the spanning tree of a BLAN, initially, each bridge assume itself is the “root bridge”, set each of it’s ports as a “designated” port, and send a BPDU to each port with its bridge ID, root bridge ID (itself), and the root path cost of 0. Which of the following statements are correct when a bridge (with root bridge ID = w, rpc = p) receives a BPDU (with root bridge ID = m, rpc =q) from port x ?
A. (a) port x will be selected as a new R port if w ＞ m
B. (b) port x will be selected as a new R port if w = m and p ＞ q
C. (c) port x will be selected as a new R port if p ＞ q
D. (d) port x will be selected as a new R port if w ＜ m
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4.14 Consider the procedure to construct the spanning tree. When a bridge (with root bridge ID = w, rpc = p) receives a BPDU (with root bridge ID = m, rpc =q) from port x (with a transmission cost of c). Assume w > m. Then what will happen ?
A. (a) Port x will be selected as a new R port.
B. (b) port x will be selected as a new D port.
C. (c) A BPDU with (with root bridge ID = m, rpc =q+c) will be forwarded to all the ports, except port x.
D. (d) A BPDU with (with root bridge ID = m, rpc =q) will be forwarded to all the ports, except port x.
E. (e) A BPDU with (with root bridge ID = m, rpc =p+q) will be forwarded to all the ports, except port x.
4.15 Consider the procedure to construct the spanning tree. When a bridge (with root bridge ID = w, rpc = p) receives a BPDU (with root bridge ID = m, rpc =q) from port x (with a transmission cost of c). Assume w ＜ m. Then what will happen ?
A. (a) Port x will be selected as a new R port.
B. (b) The BPDU will be dropped directly.
C. (c) A BPDU (with root bridge ID = w, rpc =p) will be forwarded to port x.
D. (d) A BPDU (with root bridge ID = w, rpc =q+c) will be forwarded to port x.
4.16 Consider the procedure to construct the spanning tree. When a bridge (with root bridge ID = w, rpc = p) receives a BPDU (with root bridge ID = m, rpc =q) from port x (with a transmission cost of c). Assume w = m and p > q+c. Then what will happen ?
A. (a) Port x will be selected as a new R port.
B. (b) The BPDU will be dropped directly.
C. (c) A BPDU with (with root bridge ID = m, rpc =q+c) will be forwarded to all the ports, except port x.
D. (d) A BPDU (with root bridge ID = w, rpc =q+c) will be forwarded to port x.
4.17 What is the major feature of the spanning tree constructed by the IEEE 802.1D spanning tree algorithm ?
A. (a) It is a minimum cost spanning tree. Thus, the summation of the cost of each link is minimized.
B. (b) It is a spanning tree that includes the minimum cost path of each bridge/LAN to the root bridge
C. (c) It is a spanning tree that includes the minimum cost path of each pair of bridges/LANs
D. (d) It is a minimum delay spanning tree.
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