tetap penjelasanya dengan menggunakan toplogy 3 switch:
pertama untuk UPLINKFAST:
uplinkfast harus di configure di switch yg berperan sebagai switch yg memilki link down langsung dalam hal ini di gambar switch C.jgn di switch lain gak ngaruh!!!
dannn yg menjadi jawabannya adalah switch akan mengbypass prosess listening, learning dan langsung ke forwading!
jika di switch C sebelumnya port yg arah ke switch B adalah blocking tetapi akan langsung ke forwading begitu link ke Switch A fail dan tentu saja Uplinkfast di configure di swC.
Kedua untuk BACKBONEFAST:
Jika L1 fail, sedangkan switch A adalah Backbone tetapi swB tidak dapat reachable ke swA maka swC akan bertindak sebagai backbone menuju swA dari swB.
Hi,
Consider the following Scenario:
d -SW1-d
-r -r
SW2-d b-SW3
SW1 is the root bridge and have connections to both SW2 and SW3 out of designated ports.
SW2 has connections to both SW1 and SW3 out of its root port to SW1 & designated port to Switch3.
Sw3 has connections to both SW1 and SW2 out of its root port to SW1 & Blocked port to switch2.
consdider the link between Sw1 and SW2 fails, SW2 cease to recieve hello from the root, SW2 considers itself as the new root and send it out it designated port toward SW3.
SW3 recieves inferior BPDU from SW2 and Ignore it since it has better BPDU from SW1,
SW3 waits for the maxage timer to expire , the blocking port is then moved to the listining state and starts forwards BPDUs toward SW2.
SW2 recieves Superior BPDUs and considers its new link toward the root out its designated port toward SW3.
This process is usually takes about 50 second in Normal STP operation (Hello timer + 2 * Forward delay timers), with backbone fast enabled on Sw3 and SW2 , this process doesnt wait for the Maxage timer (20 sec) to expire , as soon as SW 3 recieves inferior BPDU from SW2 it times out the maxage timer and doesnt wait for it to expire. So the whole operations takes about 30 sec.
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