??: 1. ???IP?Ethernet????.

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?????? ??
??1. ???IP?Ethernet????. 2. ?????????????. 3.
IGMP Snooping / Proxy / Server?
?????
??935602 ??? 935604 ??? 935625 ???
935627 ??? 935645 ??? 935651
??? 935657 ???
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1. IP ???? IP ??????
Version (4) Internet Header Length (4) Internet Header Length (4) Type of Service (8) Type of Service (8) Total Length (16)
Identification (16) Identification (16) Flags (3) Flags (3) Fragment Offset (13) Fragment Offset (13)
Time To Live (8) Time To Live (8) Protocol (8) Protocol (8) Header checksum (16) Header checksum (16)
Source Address (32) Source Address (32) Source Address (32) Source Address (32) Source Address (32) Source Address (32)
Destination Address (32) Destination Address (32) Destination Address (32) Destination Address (32) Destination Address (32) Destination Address (32)
Options (Variable) Options (Variable) Options (Variable) Padding (0-24) Padding (0-24) Padding (0-24)
Data???? Data???? Data???? Data???? Data???? Data????

?? bit
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Version ?? (VER)????? IP ????,??? IP ?????? 4
(version 4),?????????? 0x4 Internet Header
Length ???? (IHL)???? IP ?????????? 6 ?? header
,?? Options ? Padding??????,????5 ???? Type of
Service ???? (TOS)?????? IP ???????????????
Total Length ???? (TL)???? byte
?????????????,????????????? Identification
??? (ID)????IP?????? 16bit ?????????? OSI ?
TCP/IP ???????????????????????????,??????????????
??,???????????,?? ID ?????
4
Flag ?? (FL)?????????????????????? 3 ? bit ?????
Fragment Offset ???? (FO)????????????????(MTU)???
???,????????(fragment) ?????(???????????????,?????
????) Time To Live ???? (TTL)??? TTL
???,????????????????????? TTL ?(???????(hop)???),?
????????? Protocol ??(PROT)???????????????????,?
?ICMP ? TCP/UDP Header Checksum
?????(HC)?????????????,??????????????????????????
,??????????????????????,????????,????????,??????
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Source IP Address ????(SA)???????????,?????? IP
????,??? 32 bit Destination IP Address
?????(SA)???????? IP ??,??? 32 bit Options
Padding ?????????,????????????????,??????
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Ethernet???? EV2 ?? ??????, ?DIX ????
802.3 ?? ?IEEE ???,?????EV2?????
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• Preamble (??)
• ?7 ?Byte ???????????(Clock)??????????(0101)
• ??8 ?Byte(?802.3 ?????SFD ??)???? ?,
  ???????(???????????)????????????
• Destination Address (????)
• ????????MAC ???
• ?3 Bytes ?????, ?3 Bytes ?????
• ?0xFFFFFFFFFFFF?(??Bit ??1)??????????????,
  ?????????????????

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• Source Address (????)
• ????????MAC ???
• ????????????MAC ??, ?????
• ????
• Type (????)
• ???????(???)???????
• ??0x0800??IP?0x8137 ??IPX?
• ??????????TCP/IP?IPX?NetBeui ?????,
  ????????Payload ?????????????
• Data (??)
• ???Payload?
• ???46 Bytes ?1500 Bytes?

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• FCS(Frame Check Sequence,???????????)
• ??????(???)?????CRC (cyclic redundancy check)??
• ??????????, ??????CRC ?, ?????CRC?????,???????????
  ?
• 802.3 ?EV2 ?????
• ??SFD ?? SFD(Start Frame Delimiter, ?????)
• ??, ????EV2 ??Preamble ?????1 Byte?
• ?Type ????Length ????Payload ???????????Byte
  ???, ???461500?

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2. ?????????????.
2. ?????????????.
2. ?????????????.
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• ????Spanning Tree??????
• ?Host ????Broadcast Frame (??ARP Request)?
  Router?,Frame???Switch A???
• Switch A ??Frame ??Destination MAC Address
  ??(BroadcastFFFFFFFFFFFF),?????Frame
  Flood?Segment B?
• ?Broadcast Frame ??Switch B ?,Switch
  B???????,Flood?Frame?Segment A?
• ?Broadcast Frame ?????????????????,??Router
  ?????Frame?
• ??Bridge?Switch???????Flood????????Port?,?????????
  ??

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Spanning Tree?????? Spanning Tree
Protocol?????,???????????,?????STP?Switch?????????
?????,????(Block)????????Port,Spanning
Tree??????????,???????????,STP?????????Port???????
??????? ??Spanning Tree????Bridge?Switch??????
???,??????????BPDU (Bridge Protocol Data
Unit)?Hello Message?MulticastFrame???BPDU???,??STP
?????????????????????????
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• STP ?????????
• ????Root Bridge
• ?BPDU???????????Bridge ID,?? Bridge ???????Bridge
  ID,Root Bridge??Spanning Tree???????Bridge
  ID?Bridge?Switch?
• Bridge ID??Bridge Priority (2 Bytes)?Bridge MAC
  Address (6 Bytes)???,???802.1D Bridge
  Priority??32768?????,??Switch?Bridge
  Priority?32768 (?????8000),?MAC
  Address?0A0C5123456,??Bridge
  ID?800000A0C5123456?
• Root Bridge ???Port ??Designated Port,Designated
  Port ?????Forwarding???,??Forwarding???,??Port????
  ??????

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• 2. Non-Root Bridge????Root Port
• ????Root ?Bridge?Switch??,??????Root Port???,Root
  Port?????Non-Root Bridge??Root Bridge??,Root
  Port???????????(Leaf)????
• 1) Root Port?Non-Root Bridge??Root
  Bridge??Port??????PathCost ?Port,Root
  Port?????Forwarding ???
• 2) Path Cost?????Port????????????Frame?Root
  Bridge???Cost ???Path Cost ???????????,????????Cos
  t ????,IEEE 802.1D ????Path Cost ??????
• ????Port ?????Path Cost ???Root
  Bridge,?????PortPriority?Port????Root Port?

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• 3. ????????(Segment)????Designated Port
• ????????(Collision Domain)????Designated
  Port,DesignatedPort????Cost???Root
  Bridge,Designated Port ????Forwarding???,????Segme
  nt?????????????Segment?????????Port ????Path
  Cost,????Bridge ID ???Port ?????Designate Port?

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• 4. Spanning Tree Protocol???
• ?STP?????Cost?Spanning Tree
  ?,???Enable???Root Port?Designated
  Port,????Port?????Disable,???????Root
  Port?Designated Port ????,??????????????????STP
  ????????????BPDU,????????????,????Spanning
  Tree??????????????????????,???Bridge?????Root
  Bridge??????Hello BPDU,?????Bridge???????????(Max
  Age)????Hello BPDU,?Bridge??????Root
  Bridge?????,???Bridge ?????Bridge
  ?????????,?????????????

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• 3. IGMP Snooping / Proxy / Server?
• IGMPIGMP(Internet Group Management
  Protocol)?IP??????????????????????????????????,???
  ????IGMP?????????IGMP?????????????????????????????
  ??????IP????????,??????????????????

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• IGMP Snooping ????
• IGMP Snooping(Internet Group Management Protocol
  Snooping)????????????????????,???????????
• IGMP Snooping?????????????????????????????IGMP???,
  IGMP Snooping??IGMP?????????????????IGMP??????(IGM
  P host report message)?,?????????????????????????
  ???IGMP????(IGMP leave message)?,?????????????????
  ?????????IGMP??,??????????????MAC????????,????????
  MAC?????????????????????

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• ????IGMP Snooping?,???????????
  ?????

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• ??IGMP Snooping?,?????????,?????????
• ?????

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• ??IGMP Snooping??????
• ??????????IGMP Snooping???IGMP?????,??????????????
  ??????????????IGMP Snooping,???????????IGMP???????
  ??

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• IGMP??????IGMP???????????????????????,???????????
  ??????IGMP???????,????????????????????,???????????
  ?????????????????????????????,???????????????????
  ????,?????????????????
• IGMP???????IGMP????????????????????????,?????????
  ????????????????IGMP????????,??????IP??????????

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• IGMP????IGMP????????????????????,???????????????
  IGMP??????????????IGMP?????,???????????IP??????MAC
  ???????????????MAC??????,?????????????????,????MAC
  ???,????????????MAC????,???????????,???????VLAN???
  ???????????MAC??????,????IP???,?????????????IP????
  ????????MAC???????,?????????????MAC????,?????????
  ???MAC???????????????,??????????IP????????????,??
  ?IP????????????????IP????,?????????????????IP????
  ????????MAC??????,?????????????????MAC???,????????
  ????????????

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• IGMP????IGMP?????????????????????,??????????????
  ???????????????IP????????,????????????????????????
  ??,????????????????????????,??????????????????????
  ??????????????????,???????MAC?????????MAC?????????
  ??,???????????????????????

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• IGMP Proxy ????
• Proxy????
• ?????(proxy server)?????????????????????????
• ?????????,??????????????????????????,?????????????
  ????????,?????????,?????????????,?????????????????
  ??????????,??????????,?????????????????(firewall)?

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• ??(proxy)???,???????????????????,?????????????????
  ??,??????????????,???????????????,????????????????
  ,???????????????????????????????????????(Cache
  Server),????????????????,??????????,??????????????
  ????,??,????????,???,??????,?????,??????????????,?
  ??????????????,?????????,?????????,???????????,???
  ????????????,?????????????????????????,?????????

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• Proxy????
• Proxy???????????,????????http???????????,?????????
  ?,????????????????????,?????,???????????,???????,?
  ????????????,?????????http??????????????,??????,??
  ????????????????,??????????,?????????????????

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• Proxy???????????

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• ????proxy??
• ????????????????????????????,????,????????????????
  ,?????,??,?????????proxy???

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• ?????,??????www??????????(?proxy1?proxy2)??Interne
  t,??proxy2??,?proxy2????cache????????????,???proxy
  3????????,???,??proxy3??proxy2,??proxy2?????????pr
  oxy3?????,proxy2???proxy4???,?proxy4????????,??,?p
  roxy4????????,??????????????,?????proxy2,??proxy2?
  ????,???????????????,proxy4??proxy2???,?????,???(?
  ??proxy2)?????,??(???proxy4)????,?proxy2?proxy3???
  ??(sibling),proxy2????,???????(???proxy3)???????,?
  ???,?????,??proxy3?????,proxy2?????????????proxy??
  ,?????????????,??????????????proxy????????????????
  ??????,?????????????(????????),???????????????????
  ???,??????????

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