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These are the user uploaded subtitles that are being translated: 1 00:00:00,000 --> 00:00:07,000 align:middle line:84% So how is this rapid convergence or rapid transition to forwarding state 2 00:00:07,000 --> 00:00:11,000 align:middle line:84% accomplish in 802.1W or Rapid Spanning Tree . 3 00:00:11,000 --> 00:00:15,000 align:middle line:84% This is one of the most important features introduced in Rapid Spanning Tree 4 00:00:15,000 --> 00:00:17,000 align:middle line:84% the difference is that legacy Spanning Tree 5 00:00:17,000 --> 00:00:23,000 align:middle line:84% in other words, the legacy Spanning Tree algorithm passively waited for the network 6 00:00:23,000 --> 00:00:27,000 align:middle line:84% to converge before moving a port into the forwarding state. 7 00:00:27,000 --> 00:00:30,000 align:middle line:84% Achieving faster convergence was a matter of tuning 8 00:00:30,000 --> 00:00:36,000 align:middle line:84% the conservative default parameters are forward delay and max_age timers. 9 00:00:36,000 --> 00:00:41,000 align:middle line:84% so in the past, you would try and manipulate these timers to get Spanning Tree 10 00:00:41,000 --> 00:00:48,000 align:middle line:84% to converge quicker but this often resulted in the sacrificing of network stability. 11 00:00:48,000 --> 00:00:53,000 align:middle line:84% Rapid Spanning Tree is able to actively confirm that a port can safely transition 12 00:00:53,000 --> 00:00:58,000 align:middle line:84% to forwarding without relying on any timer configuration. 13 00:00:58,000 --> 00:01:01,000 align:middle line:84% that’s the big difference it do went rely on timers 14 00:01:01,000 --> 00:01:06,000 align:middle line:84% there is a negotiation between the switches on point-to-point links 15 00:01:06,000 --> 00:01:09,000 align:middle line:84% to allow them to converge quicker. 16 00:01:09,000 --> 00:01:11,000 align:middle line:84% so there’s a feedback mechanism that operates 17 00:01:11,000 --> 00:01:16,000 align:middle line:84% between Rapid Spanning Tree compliant bridges to achieve faster convergence 18 00:01:16,000 --> 00:01:19,000 align:middle line:84% you need to configure edge port and links between switches 19 00:01:19,000 --> 00:01:23,000 align:middle line:84% you need to become point-to-point links. 20 00:01:23,000 --> 00:01:27,000 align:middle line:84% Now an edge point is essentially the same as Portfast ports 21 00:01:27,000 --> 00:01:30,000 align:middle line:84% they transition immediately to the forwarding state. 22 00:01:30,000 --> 00:01:35,000 align:middle line:84% This is to allow end stations to skip the listening 23 00:01:35,000 --> 00:01:38,000 align:middle line:84% and learning stages in Spanning Tree convergence 24 00:01:38,000 --> 00:01:42,000 align:middle line:84% an edge port also does not generate topology changes 25 00:01:42,000 --> 00:01:44,000 align:middle line:84% when its link toggles 26 00:01:44,000 --> 00:01:46,000 align:middle line:84% so in other words, when a link goes down or comes up 27 00:01:46,000 --> 00:01:49,000 align:middle line:84% and its configure as an edge port or a Portfast port 28 00:01:49,000 --> 00:01:53,000 align:middle line:84% it doesn’t cause the network topology to recalculate. 29 00:01:53,000 --> 00:01:57,000 align:middle line:84% Unlike Portfast through an edge port that receives the BPDU 30 00:01:57,000 --> 00:02:01,000 align:middle line:84% immediately losses it's edge port status 31 00:02:01,000 --> 00:02:03,000 align:middle line:84% and becomes normal Spanning Tree port 32 00:02:03,000 --> 00:02:08,000 align:middle line:84% that is a built-in security mechanism to stop someone accidentally plugging in 33 00:02:08,000 --> 00:02:13,000 align:middle line:84% a switch or a hub into Portfast port and causing a loop. 34 00:02:13,000 --> 00:02:19,000 align:middle line:84% In Cisco's implementation, the portfast command is used for edge port configuration 35 00:02:19,000 --> 00:02:22,000 align:middle line:84% thus making the transition to Rapid Spanning Tree simpler 36 00:02:22,000 --> 00:02:27,000 align:middle line:84% in a separate video, I'll show you the configuration and testing of Portfast ports. 37 00:02:27,000 --> 00:02:31,000 align:middle line:84% I’ve already demonstrated how to set up a point-to-point link 38 00:02:31,000 --> 00:02:36,000 align:middle line:84% this is automatically determined on physical switches using the duplex of a port. 39 00:02:36,000 --> 00:02:41,000 align:middle line:84% A port operating in full duplex is assumed to be point-to-point 40 00:02:41,000 --> 00:02:44,000 align:middle line:84% half duplex is considered to be a shared port. 41 00:02:44,000 --> 00:02:50,000 align:middle line:84% On switch 2 in this topology gigabit 0/0 is a point-to-point link 42 00:02:50,000 --> 00:02:54,000 align:middle line:84% gigabit 0/1 is a shared port because it's connected to a hub. 43 00:02:54,000 --> 00:02:57,000 align:middle line:84% it’s a half duplex connection. 44 00:02:57,000 --> 00:03:01,000 align:middle line:84% In today’s networks, most links are operating in full duplex mode 45 00:03:01,000 --> 00:03:06,000 align:middle line:84% and are therefore treated as point-point links between switches in Rapid Spanning Tree 5606