Vì vậy, không bỏ qua nó! (Cisco cho rằng đó là tốt đẹp quá!)Hợp lệ mạng con? Được rồi, bây giờ cho một phần khó khăn. , và như vậy, cho octet thứ ba. Nhưng bạn không thể quên một bit subnet được sử dụng trong Octet thứ tư. | 140 Chapter 2 Implementation Operation Once you ve established which switch has got to be the root bridge look at the figure again and try to figure out which is the root port on each of the switches. Hint Root ports are always designated ports which means they are always in forwarding mode. Okay next try to establish which of the ports will be in blocking mode. Figure has the answers for each of the port states for each switch. FIGURE Spanning tree example answers Since Switch A has the lowest MAC address and all five switches use the default priority Switch A gets to be the root bridge. And remember this a root bridge always has every port in forwarding mode designated ports . To determine the root ports on Switch B and Switch C just follow the connection to the root bridge. Each direct connection to the root bridge will be a root port so it will become designated. On Switches D and E the ports connected to Switches B and C are Switches D and E s closest ports to the root bridge lowest cost so those ports are root ports and are in forwarding mode designated . Take another look at the Figure . Can you tell which of the ports between Switch D and E must be shut down so a network loop doesn t occur Let s work it out since the connection from Switches D and E to Switches B and C are root ports those can t be shut down. Next the bridge ID is used to determine designated and nondesignated ports so because Switch D has the lowest best bridge ID Switch E s port to Switch D will become nondesignated blocking and Switch D s connection to Switch E will be designated forwarding . 2J Manage System Image and Device Configuration Files 141 If you have fewer than six switches in your internetwork then depending on the number of users in your network you d usually just let STP do its job and not worry about it. If you have fewer than 6 switches in your network you probably don t need to worry too much about spanning tree. But if you have dozens of switches and .
