Spanning Tree Protocol

Spanning Tree Protocol

Spanning Tree Protocol

?????????????? Spanning Tree 
???????????? ?????????????????????????????????????  ??? Switch/Bridge ????????? ?????????????????????????????????????????? (fault tolerance) ????????? ??????????????????????????????????????????????? ????????????????????????? ????????????????????????? ???????????? Switch ?????????? ?????????????????????????????????? Network ?????? Switch ???????????????????????????????????????????????????? ???????????? Bridge Loop  ??? Bridge Loop ??????????????????????????? Switch ?????????????????????????????????? Switch ??????? ???????????? Network ??? Switch ??????? ???????? CPU Switch 100% ???????????????????????? Spanning Tree Algorithm ??????????????????????

??????? Bridge Loop ?? Network Switch

????????????????? Bridge Loop ?? Switch 

      ?????? Spanning Tree Protocol (STP) ??????????????????????????????????????????????????????????????????????? ???????????????????????? "block" ??? Port ??? switch ???????????????????????????????? ???????????????????????? Topology Network ????????????????????????????????? "block" Port ??????????????? Port ??????????????????????????????????

????????????????????????????? Spanning Tree 

      ????? ??????????????? (path) ?????????????????????????????? (loop free path) ?????????????????????????????????????????????????????????????????????? Network (Root bridge) ??????????? Switch ??????????????? ???????????????? ???????????????????????? (loop free path) ???????????????????????????????????????? Spanning Tree ??????????????????? Switch ????????????????????????????? Root bridge ??????????????????????? Port ??? Switch ????????? blocking state ????????? forwarding state ?????????????????

Note: Switch ??? Cisco ?? Enable ???????? Spanning Tree Protocol ???????????????? (by Default) ??????????????????????????????????????????????????????????????? Bridge loop ?? Network ???

??????????????? Spanning Tree
     STP ??????????? IEEE802.1d  ???? SpanningTree Algorithm ??????????????????? Root Bridge (Root Switch) ?????????????????????????????????? Network (Root Bridge) ?????????????????? port Switch ?????????????????????????????? Forwarding state ???? Port ????????????????????? ???????? Blocking state ???????????? (?????????????????? Minimum Spanning Tree Algorithm ??????????????????????????)



?????????? ??? STP ??? 3 ???????????????????????????? forwarding state ??????
      1. STP ???????????? Root Bridge ???? Port ???????????????????? forwarding state ??????????? 1 Root Bridge ??? 1 Layer 2 Domain (???????????? VLAN ??????????)
      2. Switch ????????????? Root Bridge (non-Root bridge) ???????????????????????????????????????????????????? "Root Port" ??????????????? Root port ???????????????????? "Root Path Cost" ?????????? (Cost ????????????? ????? Root Bridge) ????????????? Port ????? ?? switch ??????????? ??????????????? Root Port 1 ???????? Switch 1 ??? ???? Root Port ????? Set ??????? Forwarding state
     3. ??????? Segment ????????? Connection ??????????????????? Switch ?? Connection ??????????? STP ??????????????????????? Switch ?????????????????????????? "Designated Port" ??? "Designated Port" ???????????????????? "Root Path Cost" ????? ??? ???? Cost ??? Switch ???????? ????? Root Bridge ?????????????????????????????? Switch ???????? ??????????????????? Segment ???????? ??????????????? Designated Port 1 Port ??? 1 Segment ??????? 1 Connection ??????? Switch ??????????? Designated port ????????????????????? Forwarding state ??????? ?????????? ?????????????? Switch ????????????????????? Blocking state ???????

????????????????? Spanning Tree Protocol 

Step 1. ????? Root Bridge
            STP ?????????????????? Switch ???????????????????????????? Root Bridge ?????????? Message ??????????? BPDU (Bridge Protocol Data Unit) ????????????? Switch ???????? ????? "?????????" ?????? Switch ?????????????????????? (?????????????????) ???????????????????????? "Root Bridge" ???????? BPDU ?????????????????????????????? Bridge ID
???? Bridge ID ????????????? 8 byte ????????????????????????
- Bridge Priority (2 byte) ????????????????????? (priority)??? Switch ????????????????? Switch ??????? (???????????? 0 - 65,535) by default ??? 32,768 (2^15)
- Mac address (6 byte) ???? Mac address ???????? Switch ?????????? Switch ??????????  ?????? Hard code ???????? Switch ??????????? ???????????????????????????????

Note:  BPDU  ???? Frame ?????????????? Switch/Bridge ???????????????????????????????????? ?????????????? SpanningTree Algorithm ???????????????????????????????? ????????????? BPDU ?????????????
?????? Root Bridge ?????????? ??? Bridge ID ??????? Switch ????? Frame ???????????? port ?????? STP ???????????????????? Mac address ????????????????? Mac address ??? port ????? ?????????? Mac address ??????????? Multicast address 01-80-c2-00-00-00 ???????? Multicast ??????????????????????? Switch/Bridge ?????? STP ???????????????????? Switch/Bridge ??????????????????? ???????????????????? Root Bridge/Root switch ??? Layer 2 ?? Domain ????????????????????????????????????????????????
BPDU ????????????????? 2 ?????? ???
1. Configuration BPDU ???? BPDU ?????????????????? STP
2. Topology Change Notification (TCN) BPDU  ???? BPDU ???????????????????? Switch/Bridge ????? ?????????????????????  Topology ????????????? Network

          BPDU ??????????????????? ????????????????? 2 ???????????? Switch ????? ??????? Topology ????????????????????????? BPDU ?????????????????????? ???????????? ??????
1. Message Type ??????????? configuration BPDU ????   Topology Change BPDU
2. Root Bridge ID
3. Sender Bridge ID
4. Root Path Cost
5. Message Age
6. Maximum Age
7. Hello Time
8. Forward Delay

     ????????? Switch ?????? Switch ?????????????????? BPDU ???????????????? Root Bridge ID ????????????? Bridge ID ????????? (???????????????????????????? Root Bridge) ??????????? Sender Bridge ID ??????? Bridge ID ????????? (?????????????????????????????? BPDU ????? ????????????????) Switch ??????????????????? BPDU ????????? Port ??? ???????? ????????????????????????? BPDU ???????????????? Bridge ID ????????????????????????? Bridge ID ????? ??????????????????? ??????? Bridge ID ????? ??????????????????????????? 

     ???????? BPDU ???????? Bridge ID ????????? ???????????????? Root Bridge ID ?????? BPDU ??????????????????????????? Bridge ID ????????? BPDU ?????????????? ?????????????????????? Sender Bridge ID ????????????? Bridge ID ????????????????????????  ???????????????????? Root Bridge ?????? ??????? Switch/Bridge  ??????? Switch ???????? Bridge ID ??????????? (???????????) ???????????????????? ??????? Root Bridge ????????????????????? Designated Port ?? Segment ????? ??????????????

     ??????????? Root Bridge ???????? ?????????? Swtich ???????????????????? Network ???? Bridge ID ??? Switch ????????????????????????????????????????????????? 2 ???????????????????? BPDU  ???

??????????? ???????????????????????????????????????????? ^^

     ????????????????????? Bridge ID ???????? ?????? Bridge Priority ??????????????????????????????????????????? ?????????????? Switch ???? ?????????? Default Bridge Priority (32,768=2^15) ?????????? ?????????????????? ??????????????????????????????????? Mac address ???????? Switch ??????????? Switch ?????? ?????????????????????????????? Root Bridge ???????????? Root Bridge ????????????????????? Designated Port ???????????? ??????????

Note: Bridge ID ??? ID (Mac adddress) ???????????????? ???????????????

Step 2. ???????? Root Port

             ????????????????????? Root Bridge ????????? Switch ????????????????? Root Bridge ????????????????????? ????????????????? ??????????????????????????????????????????????????????????????? Root Bridge ??????????????? Root Port ??????????????????????????????????? Switch 1 ??? ???? STP ????????????? "Root Path Cost" ?????????????????????? Port ??????????????? Root Port ????????????? Cost ????????????????????????????????? ????????? Link ???? Connection ??? Switch ??????? Path cost ???????????? 

      Path Cost ??????????????????????????? Bandwidth ??? Link ????????? Link ????? Bandwidth ??? ??????? Path Cost ?????? ??? Link ????? Bandwidth ??????????? Path cost ?????? ??????????????? "Root Path Cost" ???????????????????? Path Cost ????????????? Root Bridge ??????????????? ?? Non-Root Bridge ???????? (Cumulative path cost = ?????????)

      ??????? Path cost ??? SpanningTree Protocol ?????? IEEE ???????????????????????

??????????????????? Root Path Cost

1. Root Bridge ??? BPDU ??????????????????? Root Path Cost ?????????? 0 ???????????????????????????? Root Bridge

2. ????? Switch ???????? ?????? BPDU ??? Root Bridge ????????????? Path Cost ????????????????????????? Root Bridge ??????????????????? Root Path Cost ??????? BPDU ???????????????

3. ??????? Switch ????????????? Root Bridge ??????????????? switch ???????? ?????????

4. ???????? Root Path Cost ??????????????????????????????????? ?????? BPDU ?????????????? switch ?????????????????

Note: ???????? Root Path Cost ??????????????????????? Switch ?????? BPDU ?????????????? ??? Root Path Cost ?????????????????

Step 3. ????? Designated Port 

             ??????????????? Root Bridge ??? Root Ports ????????? ??????????????????????????????????? Designated port ????? Segment ????? ???????? Active ??????????? Status = blocking state ??? ????????????????????????????? Designated port ????? ??????????????????????? Root Path Cost ????????? ???????????????????????????????????????????? Root Bridge ??????????????????????? ?? Segment ????????

Spanning Tree Protocol ?????????????????????? Root port ??? Designated port ??????

        1. ??????????????? Root Path cost ????????????? ?????????????????? ???????????????

2. ?????????????? Designated Port ???????  Switch ??????????????? ???????????????? Switch ????? Bridge ID ????????? 

    ?????????????? Root Port ?? Switch ???????????????????????????????? Switch ??????????? Bridge ID ???????

3. ?????????????????? Port ID ?????????

??????? ??????? ??????????????? ?????????????????????????????????????? Lab ????????????????????  ????????????????????? >>> 

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