參考stp生成樹協(xié)議

STP的概念冗余拓?fù)銼erver/host

XRouter

YSegment

1Segment

2冗余拓?fù)淠軌蚪鉀Q單點(diǎn)故障問題；冗余拓?fù)湓斐蓮V播風(fēng)暴,多幀復(fù)用,MAC地址不穩(wěn)定的問題；Switch

ASwitch

BSTP的概念廣播風(fēng)暴Host

X發(fā)送廣播幀；交換機(jī)繼續(xù)沒完沒了的更新廣播流量；Server/host

XRouter

YSegment

1Segment

2Switch

ASwitch

BBroadcastSTP的概念多幀Server/host

XRouter

YSegment

1Segment

2Host

X發(fā)送一個(gè)單播數(shù)據(jù)幀給Router

Y；Router

Y的MAC地址還沒有被每個(gè)交換機(jī)學(xué)習(xí)到；Router

Y接收2份相同的數(shù)據(jù)幀的拷貝；Switch

ASwitch

BunicastSTP的概念MAC表紊亂Server/host

XRouter

YSegment

1Segment

2Host

X發(fā)送一個(gè)單播數(shù)據(jù)幀給Router

Y；Router

Y的MAC地址還沒有被每個(gè)交換機(jī)學(xué)習(xí)到；Switches

A

and

B在Port1上學(xué)習(xí)到Host

X的MAC地址；到達(dá)Router

Y的數(shù)據(jù)幀被泛洪；Switches

A

and

B不正確的在Port2上學(xué)習(xí)到Host

X的MAC地址；Switch

ASwitch

BunicastSTP的概念復(fù)雜的多環(huán)網(wǎng)絡(luò)Server/hostWorkstationsLoopLoopLoopBroadcastSTP的概念采用生成樹STP解決環(huán)路–

Spanning-Tree

Protocol通過將特定的端口選為Blocking

state，來實(shí)現(xiàn)無環(huán)的拓?fù)?；IEEE

802.1D規(guī)定了這一行為；Cisco采用IEEE802.1D的增強(qiáng)的私有協(xié)議生成樹PVST+;STP的操作每個(gè)廣播域選擇一個(gè)根橋每個(gè)非根橋上選擇一個(gè)根端口每個(gè)段選擇一個(gè)指定端口選擇一個(gè)非指定端口10BASE-TSW1SW2SW3ROOT10BASE-TRoot

portDesignated

portDesignated

portRoot

port100BASE-TDesignated

portSTP的操作每個(gè)廣播域選擇一個(gè)根橋BPDU

(default

=

sent

every

2

seconds)Root

bridge

=

bridge

with

the

lowest

bridge

IDBridge

IDSwitch

YDefault

priority

32768(8000

hex)MAC

0c0022222222Switch

XDefault

priority

32768(8000

hex)MAC

0c0011111111BPDU橋優(yōu)先級2字節(jié)6字節(jié)橋MAC地址STP的操作BPDUSTP的操作每個(gè)廣播域選擇一個(gè)根橋每個(gè)非根橋上選擇一個(gè)根端口100BASE-T10BASE-T10BASE-TSW1SW2SW3ROOTDP

Designated

portRP

Root

port根端口：具有最低根路徑的接口要考慮的因素：1最低的根橋ID2最低的根路徑代價(jià)3最低發(fā)送者橋ID4

最

口IDSTP路徑開銷Link

SpeedCost

(New

IEEESpecification)Cost

(Old

IEEESpecification)10

Gb/s211

Gb/s41100

Mb/s191010

Mb/s100100最短路徑是cost累加，而cost是基于鏈路的速率的。STP的操作每個(gè)廣播域選擇一個(gè)根橋每個(gè)非根橋上選擇一個(gè)根端口100BASE-T10BASE-T10BASE-TSW1SW2SW3ROOTDP

Designated

portRP

RootportRPRP根端口：具有最低根路徑的接口要考慮的因素：最低的根橋ID最低的根路徑代價(jià)最低發(fā)送者橋ID最

口IDSTP的操作每個(gè)廣播域選擇一個(gè)根橋每個(gè)非根橋上選擇一個(gè)根端口每個(gè)段選擇一個(gè)指定端口100BASE-T10BASE-T10BASE-TSW1SW2SW3ROOTDP

Designated

portRP

RootportRPRPDPDP指定端口：具有最低根路徑的接口要考慮的因素：最低的根橋ID最低的根路徑代價(jià)最低發(fā)送者橋ID最

口IDSTP的操作每個(gè)廣播域選擇一個(gè)根橋每個(gè)非根橋上選擇一個(gè)根端口每個(gè)段選擇一個(gè)指定端口阻塞非指定端口100BASE-T10BASE-T10BASE-TSW1SW2SW3ROOTDP

Designated

portRP

RootportRPRPDPDPSTP案例CASE1SW1SW2SW3Pri

32768Mac

0C00.1111.0000ROOTDPPri

32768Mac

0C00.1111.1111Pri

32768Mac

0C00.1111.2222100

BASE-TRPRPSTP案例CASE2SW1SW2SW3ROOTDPPri

32768Mac

0C00.1111.1111Pri

32768Mac

0C00.1111.2222100

BASE-TRPRPPri

32768Mac

0C00.1111.0000DPDPSTP案例CASE3Pri

32768Mac

0C00.1111.0000ROOTSW1SW4SW2SW3Pri

32768Mac

0C00.1111.1111Pri

32768Mac

0C00.1111.3333RPRPPri

32768Mac

0C00.1111.2222RPDPDPDPDPSTP案例CASE4Pri

32768Mac

0C00.1111.0000ROOTSW1SW2Pri

32768Mac

0C00.1111.2222RPDPDPSTP的端口狀態(tài)STP的端口狀態(tài)In

the

blocking

state,

ports

can

only

receive

BPDUs.

It

may

take

up

to20

seconds

to

change

from

thisstate；In

listening

state,

switches

determine

if

there

are

any

other

paths

tothe

root

bridge.

the

forward

delay

and

lasts

for

15

seconds.

In

thelistening

state,

user

data

is

not

being

forwarded

and

MAC

addressesare

not

being

learned；In

learning

state

user

data

is

not

forwarded,

but

MAC

addresses

arelearned

from

any

traffic

that

is

seen.

The

learning

sta asts

for

15seconds

and

isalso

called

theforward

delay；In