{"id":805,"date":"2008-05-05T12:20:00","date_gmt":"2008-05-05T04:20:00","guid":{"rendered":"http:\/\/note.systw.net\/note\/?p=805"},"modified":"2023-11-05T12:25:34","modified_gmt":"2023-11-05T04:25:34","slug":"802-1d-stp","status":"publish","type":"post","link":"https:\/\/systw.net\/note\/archives\/805","title":{"rendered":"802.1D STP"},"content":{"rendered":"\n

STP(spanning tree protocol,\u64f4\u5145\u6a39\u5354\u5b9a)<\/strong>
IEEE\u4ee3\u865f\u70ba802.1D
\u5728\u5be6\u9ad4\u6709\u4e92\u9023\u8a2d\u5099\u4e0a\u7522\u751f\u908f\u8f2f\u6a39\u72c0\u7d50\u69cb,\u53ef\u907f\u514dframe\u50b3\u9001\u767c\u751floop
ps:\u7b2c\u4e8c\u5c64frame\u7121ttl(time to live,\u5b58\u6d3b\u6642\u9593)\u7684\u8a2d\u5b9a,\u56e0\u6b64\u53ef\u80fd\u9020\u6210loop
\u8def\u5f91\u4e2d\u65b7\u53ef\u63d0\u4f9b\u5099\u63f4\u8def\u5f91(\u6539\u8b8aPORT\u72c0\u614b)
\u589e\u52a0\u5927\u7db2\u8def\u74b0\u5883\u64f4\u5145\u6027
\u5c6cOSI layer2
ps:\u539f\u70badec\u8a2d\u8a08,\u5f8c\u4f86ieee\u5efa\u7acb\u81ea\u5df1\u7684\u7248\u672c\u70ba802.1d<\/p>\n\n\n\n

stp\u53ef\u80fd\u7522\u751f\u7684\u554f\u984c<\/strong>
\u4f9d\u9810\u8a2d\u512a\u5148\u6b0a\u81ea\u52d5\u8a08\u7b97stp\u53ef\u80fd\u4f7f\u7db2\u8def\u6548\u80fd\u8b8a\u5dee:
\u3000\u56e0\u70ba\u6548\u80fd\u6700\u5dee\u6216\u62d3\u7f6e\u4f4d\u7f6e\u6700\u5dee\u7684switch\u53ef\u80fd\u8b8a\u6210root bridge,
\u3000\u7576\u6240\u6709switch\u90fd\u9700\u6d41\u7d93\u6548\u80fd\u6216\u4f4d\u7f6e\u6700\u4e0d\u597d\u7684root bridge\u6642,\u9019\u6703\u8b8a\u6210bottleneck
\u89e3\u6c7a\u8fa6\u6cd5:
\u3000\u5c07\u7406\u60f3\u8207\u5099\u63f4\u7528\u7684switch\u512a\u5148\u6b0a\u8abf\u9ad8,\u4f7f\u8f03\u5feb\u6216\u4f4d\u7f6e\u8f03\u597d\u7684\u8a2d\u5099\u6210\u70baroot bridge\u4ee5\u8a08\u7b97\u8f03\u51fa\u8f03\u597d\u7684stp
<\/p>\n\n\n\n

stp\u6709\u4ee5\u4e0b\u5e7e\u985e<\/strong> 
cst(common spanning tree)<\/strong>:\u4e5f\u5c31\u662f802.1d,\u4e00\u822c\u7684stp,\u591a\u500bVLAN\u4e00\u500bSTP,\u53ea\u5728802.1q\u4e0a\u904b\u4f5c 
pvst(per vlan spanning tree)<\/strong>:cicso\u5c08\u5c6c\u5354\u5b9a,\u4e00\u500bVLAN\u4e00\u500bSTP,\u53ea\u5728ISL\u4e0a\u904b\u4f5c,\u4e14\u7121\u6cd5\u8207\u4ed6\u5ee0\u7684stp,rstp\u76f8\u5bb9
pvst+<\/strong>:cisco\u5c08\u5c6c\u5354\u5b9a,\u4e00\u500bVLAN\u4e00\u500bSTP,\u53ef\u5728ISL\u548c802.1q\u904b\u4f5c,\u4e5f\u548c\u5176\u4ed6\u5ee0\u724c\u7684stp,rstp\u76f8\u5bb9
RSTP(rapid stp,\u5feb\u901f\u64f4\u5f35\u6a39)<\/strong>:ieee802.1w,\u6539\u826fstp\u7684\u6536\u6582\u901f\u5ea6,\u4ee5\u6eff\u8db3\u8a9e\u97f3\u548c\u8996\u983b\u7684\u9700\u6c42
MST(multiple stp,\u591a\u91cd\u64f4\u5f35\u6a39)<\/strong>:ieee802.1s,\u5141\u8a31\u7db2\u7ba1\u5728trunk\u4e0a\u5efa\u7f6e\u591a\u500b\u64f4\u5f35\u6a39,\u4e26\u5c0d\u61c9\u5230\u4e00\u500bspanning tree instance<\/p>\n\n\n\n

…………………………………… <\/p>\n\n\n\n

loop\u53ef\u80fd\u5f15\u767c\u7684\u554f\u984c\u6709:
broadstorm(\u5ee3\u64ad\u98a8\u7206)
multiframe(\u5c01\u5305\u91cd\u8986)
table instablity(mac\u8868\u4e0d\u7a69\u5b9a)<\/p>\n\n\n\n

loop\u6d41\u7a0b <\/strong>
\u5047\u8a2d\u67092switch\u53ea\u6709port1\u548cport2,port1\u8207pc1\u7db2\u8def\u9023\u7d50,\u800cport2\u8207pc2\u7db2\u8def\u9023\u7d50(loop\u60c5\u6cc1)
1
(src mac)pc1 \u50b3\u9001frame(unicast)\u5230(dst mac)pc2,
\u6839\u64dalisten\u898f\u5247,pc1\u7684frame\u6703\u9032\u5165switch1\u548cswitch2\u7684port1
mac-table\u5982\u4e0b
switch1:null on port1
switch1:null on port1
2
switch1\u7684port1\u6536\u5230frame,\u6839\u64dalearn\u898f\u5247\u8a18\u9304(src mac)pc1mac on port1,\u4e26\u6839\u64daflood\u898f\u5247\u5c07frame\u5f9eport2\u9001\u51fa
switch2\u7684port1\u6536\u5230frame,\u6839\u64dalearn\u898f\u5247\u8a18\u9304(src mac)pc1mac on port1,\u4e26\u6839\u64daflood\u898f\u5247\u5c07frame\u5f9eport2\u9001\u51fa
mac-table\u5982\u4e0b
switch1:pc1mac on port1
switch1:pc1mac on port1
3
\u6839\u64dalisten\u898f\u5247,switch1\u9001\u51fa\u7684frame\u6703\u9032\u5165switch2\u7684port2
switch2\u6839\u64dalearn\u898f\u5247\u5c07\u8a18\u9304\u66f4\u6539\u6210(src mac)pc1mac on port2,\u4e26\u6839\u64daflood\u898f\u5247\u5c07frame\u5f9eport1\u9001\u51fa
\u6839\u64dalisten\u898f\u5247,switch2\u9001\u51fa\u7684frame\u6703\u9032\u5165switch1\u7684port2
switch1\u6839\u64dalearn\u898f\u5247\u5c07\u8a18\u9304\u66f4\u6539\u6210(src mac)pc1mac on port2,\u4e26\u6839\u64daflood\u898f\u5247\u5c07frame\u5f9eport1\u9001\u51fa
mac-table\u5982\u4e0b
switch1:pc1mac on port2 (mac-table\u66f4\u52d5\u7b2c1\u6b21)
switch1:pc1mac on port2 (mac-table\u66f4\u52d5\u7b2c1\u6b21)
4
\u6839\u64dalisten\u898f\u5247,switch2\u9001\u51fa\u7684frame\u6703\u9032\u5165switch1\u7684port1
\u6839\u64dalearn\u898f\u5247\u5c07\u8a18\u9304\u66f4\u6539\u6210(src mac)pc1mac on port1,\u4e26\u6839\u64daflood\u898f\u5247\u5c07frame\u5f9eport2\u9001\u51fa
\u6839\u64dalisten\u898f\u5247,switch1\u9001\u51fa\u7684frame\u6703\u9032\u5165switch2\u7684port1
\u6839\u64dalearn\u898f\u5247\u5c07\u8a18\u9304\u66f4\u6539\u6210(src mac)pc1mac on port1,\u4e26\u6839\u64daflood\u898f\u5247\u5c07frame\u5f9eport2\u9001\u51fa
mac-table\u5982\u4e0b
switch1:pc1mac on port1 (mac-table\u66f4\u52d5\u7b2c2\u6b21)
switch1:pc1mac on port1 (mac-table\u66f4\u52d5\u7b2c2\u6b21)
5
\u4e0d\u65b7\u91cd\u8986,mac-table\u6703\u4e0d\u65b7\u6539\u8b8a,frame\u6703\u4e0d\u65b7\u5f9eport1\u548cport2\u9001\u51fa\u585e\u6eff\u6574\u500b\u7db2\u8def
mac-table\u5982\u4e0b
switch1:pc1mac on port1 (mac-table\u66f4\u52d5\u7b2cn\u6b21)
switch1:pc1mac on port1 (mac-table\u66f4\u52d5\u7b2cn\u6b21)<\/p>\n\n\n\n

…………………<\/p>\n\n\n\n

id type
bridge id<\/strong>:\u7528\u4f86\u8b58\u5225\u6bcf\u4e00\u53f0switch,\u683c\u5f0f\u6709\u4ee5\u4e0b2\u7a2e
\u3000traditional 802.1d<\/strong>:\u683c\u5f0f\u70babridge priority(16bit)+unique mac address(48bit),priority\u9810\u8a2d\u70ba32768
\u3000802.1t<\/strong>:\u683c\u5f0f\u70bapriority(4bit)+vlan id\/system id(12bit)+nonunique mac address(48bit)
port id:<\/strong>\u7528\u4f86\u8b58\u5225\u6bcf\u4e00\u500bport,mac\u4f4d\u7f6e\u4e5f\u8d8a\u5927,\u901a\u5e38port id\u8d8a\u5927  <\/p>\n\n\n\n

bridge role
Root Bridge<\/strong>:\u7db2\u8def\u4e2dbridge id\u6700\u4f4e\u7684\u8a2d\u5099,\u4e00\u500b\u7db2\u8def\u4e2d\u53ea\u6703\u6709\u4e00\u500b 
\u3000ps:\u5c07\u8a2d\u5099\u512a\u5148\u6b0a\u8a2d\u4f4e\u53ef\u505aroot bridge,\u5e38\u7528\u5728\u81ea\u5df1\u6c7a\u5b9a\u6700\u4f73\u5316\u8def\u5f91\u6642
non-root\/Designated Bridge(\u4ee3\u7406\u6a4b\u63a5\u5668):\u6709designated port\u7684\u6a4b\u63a5\u5668\u3000<\/strong><\/p>\n\n\n\n

port role
RP(Root Port)<\/strong>:\u5f9e\u6b64port\u51fa\u53bb\u6703\u5f80root bridge\u7684\u65b9\u5411,\u4e14\u662f\u62b5\u9054root bridge\u7684\u6700\u77ed\u8def\u5f91\u7684\u57e0
\u3000Root Path Cost<\/strong>:bridge\u7d93\u7531\u5176root port\u5230root bridge\u7684\u8def\u5f91\u8cbb\u7528,\u6839\u64dapath cost\u7d2f\u8a08 
\u3000Transmission Cost\/<\/strong>Path Cost<\/strong>:\u5404port\u7686\u6709,\u8a0a\u6846\u7d93\u8a72port\u50b3\u9032\u9023\u63a5\u5340\u57df\u7db2\u8def\u7684\u8cbb\u7528,\u50b3\u9001\u901f\u7387\u8d8a\u5feb\u7684\u5340\u57df\u7db2\u8def,\u548c\u5176\u76f8\u9023\u63a5\u7684port\u8cbb\u7528\u8d8a\u5c0f
DP(Designated Port)<\/strong>:\u5176\u4ed6\u8a2d\u5099\u9032\u5165\u6b64port\u5c07\u6709\u689d\u6700\u5c11\u8cbb\u7528\u7684\u8def\u5f91\u5230\u9054root bridge
<\/strong>\u3000ps:root bridge\u7684\u5176\u4ed6port\u5fc5\u70badesignated port,\u56e0\u70ba\u6bcf\u500bport\u7684root path cost=0
NDP(non-Designated port)<\/strong>:blocking state\u7684port <\/strong><\/p>\n\n\n\n

ps:
path cost<\/strong>\u5982\u4e0b
bandwidth,oldcost,newcost
4Mbps ,250 ,250
10Mbps ,100 ,100
16Mbps ,63 ,62
45Mbps ,22 ,39
100Mbps ,10 ,19
155Mbps ,6 ,14
622Mbps ,2 ,6
1Gbps ,1 ,4
10Gbps ,0 ,2  tie-breaking decision process
<\/strong>stp\u6c7a\u7b56\u53c3\u6578,\u5305\u62ec\u4ee5\u4e0b
Lowest root bridge ID
Lowest root path cost to root bridge
Lowest sender bridge ID
Lowest sender port ID stp port state<\/p>\n\n\n\n

port\u72c0\u614b<\/td>\u8a0a\u6846<\/td>BPDU<\/td>\u6642\u9593<\/td>mac\u4f4d\u7f6e<\/td> <\/td><\/tr>
Blocking(\u505c\u6eef\u72c0\u614b) <\/td> <\/td>\u53ef\u6536 <\/td> <\/td> <\/td>\u7121root port\u548cdesignated port\u72c0\u614b
\u4ea4\u63db\u5668\u958b\u6a5f\u6642\u901a\u5e38\u70ba\u6b64\u72c0\u614b<\/td><\/tr>
Listening(\u50be\u807d\u72c0\u614b)<\/td> <\/td>\u53ef\u6536\/\u53ef\u9001 <\/td>\u66ab\u6642\u6027
15\u79d2\u7d50\u675f<\/td>		 <\/td>\u525b\u5f97\u5230root port\u6216designated port,\u4e26\u5728forward delay\u5167
\u82e5\u6b64\u8def\u5f91\u4e0d\u662f\u901a\u5f80root bridge\u7684\u6700\u4f4e\u6210\u672c\u5c07\u6703\u56de\u5230blocking\u72c0\u614b<\/td><\/tr>
Learning(\u5b78\u7fd2\u72c0\u614b)<\/td> <\/td>\u53ef\u6536\/\u53ef\u9001 <\/td>\u66ab\u6642\u6027
15\u79d2\u7d50\u675f<\/td>		\u53ef\u5b78\u7fd2<\/td>forward delay\u5167\u672a\u88ab\u53d6\u6d88root port\u6216designated port
\u958b\u59cb\u7522\u751fmac table<\/td><\/tr>
Forwarding(\u8f49\u9001\u72c0\u614b)<\/td>\u53ef\u50b3\u9001<\/td>\u53ef\u6536\/\u53ef\u9001<\/td> <\/td>\u53ef\u5b78\u7fd2<\/td>\u78ba\u5b9a\u5c6c\u65bc\u64f4\u5f35\u6a39\u7684\u4e00\u90e8\u5206(root port\u6216designated port)
\u53ef\u57f7\u884c\u8f49\u9001\u8a0a\u6846\u7684\u4efb\u52d9,…\u7b49<\/td><\/tr>
Disabled(\u95dc\u9589\u72c0\u614b)<\/td> <\/td> <\/td> <\/td> <\/td>\u7ba1\u7406\u4e0a\u7684\u95dc\u9589,\u4e0d\u53c3\u8207STP\u64cd\u4f5c<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

stp timer 
Forward Delay(\u8f49\u9001\u5ef6\u9072\u6642\u9593)<\/strong>:
\u4e00\u7b46\u8a0a\u6846\u5f9e\u958b\u59cb\u50b3\u9001\u5230\u8a0a\u6846\u7d93\u904e\u6240\u6709\u6a4b\u63a5\u5668\u6240\u9700\u8981\u6700\u9577\u7684\u6642\u9593,\u4e00\u500b\u9031\u671f\u9810\u8a2d15sec
ps:all forward delay 30sec=listening forward delay 15sec+learning forward delay 15sec
ps:\u8a2d\u592a\u4f4e\u53ef\u80fd\u6703\u5f62\u6210loop 
Maximum Age(BPDU\u4fdd\u5b58\u6642\u9593):
<\/strong>\u5f9e\u76f8\u9130switch\u7684DP\u4f86\u7684bpdu\u7684\u6700\u5927\u4fdd\u5b58\u6642\u9593,\u9810\u8a2d20sec 
Hello Time(\u554f\u5019\u6642\u9593)<\/strong>:
root bridge\u7522\u751fconfigure bpdu\u7684\u9593\u9694,\u5075\u6e2c\u7db2\u8def\u72c0\u614b\u7528,\u9810\u8a2d2sec 
ps:\u65b0\u7684stp\u6536\u6582\u6642\u9593\u6700\u591a\u82b1\u8cbb50sec,\u5176\u4e2dmax age 20sec\u4ee5\u53caall forward delay 30sec <\/p>\n\n\n\n

…………….<\/p>\n\n\n\n

\u5efa\u7acbspanning tree<\/strong>(\u6240\u6709LAN\u5167bridge\u5230root bridge\u7684path cost\u70ba\u6700\u5c0f)
\u6f14\u7b97\u6cd5\u5728\u6bcf\u500bbridge\u4e0a\u57f7\u884c, \u5f62\u6210\u6240\u6709bridge\u9593\u7684\u4e00\u500b\u901a\u8a0a\u5354\u5b9a
1<\/strong>\u627e\u51faroot bridge<\/strong>:\u4e00\u500blan\u53ea\u6709\u4e00\u500b,\u4efb\u4e00\u6a4b\u63a5\u5668\u5728\u4e8c\u500bforward delay\u5167\u4e0d\u6536\u5230\u6bd4\u81ea\u5df1\u5c0f\u7684root bridge id\u5c31\u53ef\u78ba\u8a8d\u81ea\u5df1\u662froot bridge
2\u627e\u51faroot port<\/strong>:\u4e00\u500bdevice\u4e00\u500b,\u78ba\u8a8d\u81ea\u5df1\u4e0d\u662froot bridge\u5f8c\u4fbf\u7acb\u523b\u5c0b\u627e\u81ea\u5df1\u7684root port
3\u627e\u51fadesignated port<\/strong>:\u4e00\u500blan segment\u4e00\u500b,designated port\u7531\u6240\u6709\u548c\u5176\u76f8\u9023\u63a5\u7684\u6a4b\u63a5\u5668\u5171\u540c\u4f86\u5c0b\u627e
\u3000\u82e5\u6709\u591a\u500bDP\u53ef\u9078\u6642,\u5247\u9078\u64c7\u9806\u5e8f\u70basend-bridge id,port cost,port id
ps:\u82e5device\u7684port\u5373\u4e0d\u662froot port\u4e5f\u4e0d\u662fdesignated port,\u5247\u8a72port\u9032\u5165blocking state
stp\u6536\u6582\u5b8c\u6210\u60c5\u6cc1<\/strong>
\u6bcf\u500bport\u7684\u72c0\u614b\u4e0d\u662fforwarding\u5c31\u662fblocking\u6642,\u4e14\u4ee5\u4e0b\u6703\u6210\u7acb
\u3000\u6b64LAN\u6709\u4e00\u500broot bridge
\u3000\u6bcf\u500b\u975eroot bridge\u6709\u4e00\u500broot port
\u3000\u6bcf\u500blan segment\u6709\u4e00\u500bdesignated port<\/p>\n\n\n\n

root bridge election process<\/strong>(\u627e\u51faroot bridge)
1
\u5404switch\u555f\u52d5\u5f8c,\u6703\u5047\u8a2d\u81ea\u5df1\u70baroot bridge,
\u4e26\u9001\u51fabpdu,\u800croot bridge id\u548csender bridge id\u90fd\u7b49\u65bcown bridge id
2
\u5404switch\u6536\u5230\u5176\u4ed6switch\u7684bpdu,
\u82e5root bridge id\u6bd4\u81ea\u5df1\u512a\u5148\u6b0a\u9ad8,\u5247\u5c07\u4ee5\u6b64\u66ff\u63db\u81ea\u5df1\u7684root bridge id,\u800c\u81ea\u5df1\u5c6c\u65bcnonroot bridge 
\u82e5\u5728\u6642\u9593\u5167\u6c92\u6709\u5176\u4ed6switch\u6bd4\u81ea\u5df1\u512a\u5148\u6b0a\u9ad8,\u5247\u8868\u793a\u81ea\u5df1\u88ab\u9078\u70baroot bridge 
ps:root bridge id\u7684\u503c\u8d8a\u5c0f,\u512a\u5148\u6b0a\u8d8a\u9ad8
3
\u6b64\u6b65\u9a5f\u6703\u6301\u7e8c\u9032\u884c,\u9810\u8a2d\u6bcf2\u79d2\u5075\u6e2c\u4e00\u6b21root bridge id <\/p>\n\n\n\n

nonroot bridge elected root port<\/strong>(\u627e\u51faroot port)
1
root bridge\u9001\u51fabpdu,
root path cost=0
2
\u6700\u9760\u8fd1root bridge\u7684nonroot bridge\u6536\u5230\u8a72bpdu\u5f8c,\u8a72\u4ecb\u9762\u5247\u70baroot port,
\u4e14root path cost+=root path,\u4e26\u653e\u5165bpdu\u5167\u9001\u51fa
3
\u9760\u8fd1\u8a72\u53f0nonroot bridge\u6536\u5230\u8a72bpdu\u5f8c,\u8a72\u4ecb\u9762\u5247\u70baroot port
\u4e14root path cost+=root path,\u4e26\u653e\u5165bpdu\u5167\u9001\u51fa
4
\u91cd\u89862-3\u6b65\u9a5f\u76f4\u5230\u5404nonroot bridge\u627e\u5230root port\u4e26\u5b9a\u7fa9\u597droot path cost<\/p>\n\n\n\n

……………………………………………….<\/p>\n\n\n\n

\u7dad\u8b77\u64f4\u5f35\u6a39<\/strong>(\u56e0\u8a2d\u5099\u7684\u6545\u969c\u6216\u640d\u58de\u53ef\u80fd\u9020\u6210\u65b7\u88c2)
\u65b9\u6cd5\u4e3b\u8981\u5206\u70ba\u5169\u90e8\u4efd:
\u65b7\u88c2\u5075\u6e2c:root bridge\u8ca0\u8cac\u63d0\u4f9b\u539f\u59cb\u8a0a\u606f
\u64f4\u5f35\u6a39\u91cd\u7d44:\u53d6\u4ee3\u8a72designated bridge\u89d2\u8272\u7684\u5de5\u4f5c <\/p>\n\n\n\n

topology change\u7684\u6b65\u9a5f <\/p>\n\n\n\n

Direct Topology Changes<\/strong>
nonroot switch a\u767c\u73feroot port\u4e2d\u65b7\u6642
1 \u767c\u73fe\u4e2d\u65b7\u7684switch\u50b3\u9001TCN BPDU\u7d66root bridge\u901a\u77e5\u6709\u8b8a\u52d5
ps:nonroot switch a\u7121\u6cd5\u900f\u904eroot port\u50b3\u9001TCN BPDU,\u56e0\u70ba\u5df1\u4e2d\u65b7
2 root bridge\u50b3\u9001config BPDU with TCN\u7d66\u4e0b\u6e38switch
3 \u6240\u6709nonroot switch\u6536\u5230config BPDU with TCN\u5f8c,\u7e2e\u77ed\u5404\u81ea\u7684BridgeTable Aging Times
4 nonroot switch a\u5c07\u6536\u5230config BPDU with TCN\u7684\u4ecb\u9762\u8a2d\u70baroot port
5 nonroot switch a\u7684root port\u7684\u72c0\u614b\u6703\u5f9elistening\u5230learning(15sec),\u5728\u5230forwarding(15sec)
\u6062\u5fa9\u9023\u7dda\u6642\u9593total 30sec<\/p>\n\n\n\n

Indirect Topology Changes<\/strong>
nonroot switch a\u767c\u73feroot port\u7121\u6cd5\u6536\u5230bpdu,\u4f46\u7dda\u8def\u6b63\u5e38
1 nonroot switch a\u7b49\u5230max age\u5f8c(20sec),\u958b\u59cb\u6e96\u5099\u66f4\u65b0bpdu
2 nonroot switch a\u5728\u5176\u4ed6port\u6536\u5230bpdu(2sec),\u5c07\u6b64port\u8a2d\u70baroot port
3 nonroot switch a\u7684root port\u7684\u72c0\u614b\u6703\u5f9elistening\u5230learning(15sec),\u5728\u5230forwarding(15sec)
\u6062\u5fa9\u9023\u7dda\u6642\u9593total 52sec<\/p>\n\n\n\n

Insignificant Topology Changes<\/strong>
nonroot switch a\u767c\u73fenon-redundant\u7684\u4ecb\u9762\u4e2d\u65b7\u6216\u555f\u7528 
1 \u8a72\u4ecb\u9762\u5931\u53bbstp\u529f\u80fd\u6216\u6062\u5fa9stp\u529f\u80fd\u4e26\u4f9d\u898f\u5247\u8b8a\u70baforwarding status 
2 nonroot switch a\u50b3\u9001TCN BPDU\u7d66root bridge\u901a\u77e5\u6709\u8b8a\u52d5
3 root bridge\u50b3\u9001config BPDU with TCN\u7d66\u4e0b\u6e38switch
4 \u6240\u6709nonroot switch\u6536\u5230config BPDU with TCN\u5f8c,\u7e2e\u77ed\u5404\u81ea\u7684BridgeTable Aging Times
ps:non-redundant\u7684\u4ecb\u9762:\u9023\u63a5\u55ae\u4e00\u7dda\u8def\u7684\u8a2d\u5099,\u5305\u62ec\u672a\u505astp\u7684switch,pc
ps:\u4e00\u4f46pc\u5920\u591a,\u5247bridgetable\u6703\u4e00\u76f4\u88ab\u4fee\u6539,\u4e5f\u8868\u793a\u6703\u6709\u66f4\u591a\u7684broadcast\u767c\u751f <\/p>\n\n\n\n

……………..<\/p>\n\n\n\n

BPDU(Bridge Protocol Data Unit,\u6a4b\u63a5\u5668\u901a\u8a0a\u5354\u5b9a\u8cc7\u6599\u55ae\u5143)
<\/strong>bridge\u5f7c\u6b64\u4e4b\u9593\u9001\u8a0a\u6846\u7684\u55ae\u5143,\u8a2d\u5b9astp\u7528
\u82e5\u4e09\u6b21\u6c92\u9001BPDU\u8868\u793a\u8a72\u8a2d\u5099\u5df1\u639b,\u6b21\u8981bridge\u6703\u63a5\u624b
ps:bpdu\u5229\u7528multicast\u6280\u8853,\u9810\u8a2dSTP multicast address\u70ba01-80-c2-00-00-00<\/p>\n\n\n\n

bpdu\u5206\u70ba:
Configuration BPDU<\/strong>:
\u3000spanning-tree\u7684\u5efa\u7acb\u6642\u5404bridge\u7528\u6b64\u7a2ebpdu\u4ea4\u63db\u8a0a\u606f
\u3000\u7576spanning-tree\u88ab\u5efa\u7acb\u5f8c,\u53ea\u6709root bridge\u80fd\u9001\u6b64\u7a2ebpdu 
TCN(Topology Change Notification) BPDU<\/strong>\uff1a
\u3000\u767c\u73fe\u64f4\u5f35\u6a39\u6709\u8b8a\u52d5\u60c5\u6cc1\u6642\u901a\u77e5root bridge,ex:\u65b7\u7dda
\u3000\u6536\u5230\u8a72bpdu\u7684device\u6703\u7e2e\u77edbridge table aging times<\/p>\n\n\n\n

Configuration BPDU\u8a0a\u6846
<\/strong>\u6b04\u4f4d\u5982\u4e0b:
protocol id(2byte):\u901a\u8a0a\u5354\u5b9a\u8fa8\u8b58\u78bc,
version(1byte):IEEE 802.1D\u64f4\u5f35\u6a39\u901a\u8a0a\u5354\u5b9a\u7248\u672c\u70ba 0000 0000
message type(1byte):BPDU\u7a2e\u985e,0000 0000\u70baConfiguration BPDU,1000 0000\u70baTCN BPDU
flags(1byte):\u6709\u67b6\u69cb\u8b8a\u66f4\u65d7\u6a19(\u7b2c1bit)\u53ca\u67b6\u69cb\u8b8a\u66f4\u56de\u8986\u65d7\u6a19(\u7b2c8bit)
root bridge id(8byte):\u8a18\u9304\u50b3\u9001\u6b64BPDU\u7684\u6a4b\u63a5\u5668\u8a8d\u5b9a\u7684root bridge\u7684\u8fa8\u8b58\u78bc,\u524d2byte\u70ba\u53ef\u8a2d\u5b9a\u8fa8\u8b58\u78bc, \u5f8c6byte\u70baMAC \u4f4d\u5740
root path cost(4byte):\u8a18\u9304\u50b3\u9001\u6b64BPDU\u4e4b\u6a4b\u63a5\u5668\u4e4broot path cost
send bridge id(8byte):\u50b3\u9001\u6b64BPDU\u7684\u6a4b\u63a5\u5668\u7684\u8fa8\u8b58\u78bc
port id(2byte):\u50b3\u9001\u6b64BPDU\u7684\u6a4b\u63a5\u5668\u57e0\u8fa8\u8b58\u78bc,priority(1byte)+interface sn(1byte)
Message Age(2byte):\u6b64 BPDU \u5df2\u7d93\u5728\u7db2\u8def\u4e2d\u751f\u5b58\u7684\u6642\u9593 (in 256ths of a second)
Maximum Age(2byte):\u6b64 BPDU \u4e4b\u6700\u5927\u751f\u5b58\u6642\u9650,\u82e5\u60f3\u6e1b\u5c11BPDU\u6d41\u91cf\u53ef\u52a0\u5927\u79d2\u6578 (in 256ths of a second)
Hello Time(2byte):root bridge\u7522\u751fBPDU\u7684\u9593\u9694\u6642\u9593,\u9810\u8a2d2\u79d2 (in 256ths of a second)
Forward Delay(2byte):bridge\u4f7f\u7528\u7684\u6642\u9593\u53c3\u6578 (in 256ths of a second)\u8fa8\u5225\u6240\u7528\u7684\u901a\u8a0a\u5354\u5b9a<\/p>\n\n\n\n

TCN BPDU<\/strong>\u8a0a\u6846<\/strong>
\u6b04\u4f4d\u5982\u4e0b:
protocol id(2byte):\u8fa8\u5225\u6240\u7528\u7684\u901a\u8a0a\u5354\u5b9a,\u9810\u8a2d\u70ba0 
version(1byte):IEEE 802.1D\u64f4\u5f35\u6a39\u901a\u8a0a\u5354\u5b9a\u7248\u672c\u70ba 0000 0000
message type(1byte):BPDU\u7a2e\u985e,0000 0000\u70baconfiguration BPDU,1000 0000\u70baTCN BPDU <\/p>\n","protected":false},"excerpt":{"rendered":"

STP(spanning tree protocol,\u64f4\u5145\u6a39 …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"","fifu_image_alt":"","_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[26],"tags":[],"class_list":["post-805","post","type-post","status-publish","format-standard","hentry","category-osi-layer2"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts\/805","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/comments?post=805"}],"version-history":[{"count":0,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts\/805\/revisions"}],"wp:attachment":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/media?parent=805"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/categories?post=805"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/tags?post=805"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}