08 BGP Attributes and Policy LocalPref Communities

8/17/2019 08 BGP Attributes and Policy LocalPref Communities

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© 2011 Juniper Networks, Inc. All rights reserved. | www.juniper.net

© 2011 Juniper Networks, Inc. All rights reserved. www.juniper.net | 2

L BGP

A

AS

L PL PAS PAS P

OO

MEDMED


2/18


L BGP I ,

100

S [edit protocols bgp]

C local-preference

P F , BGP 170

S [edit protocols bgp]

C preference

M , !


E IBGP

AS

IBGP AS

172.17.2.0?

R B

IBGP

172.17.2.0/24

EBGP

IBGP R B

B

AS AS

A


3/18


A OC12 OC3

1

A

IBGP

B C

192.168.27.0/24

10 GE1 GE

R1 R2

192.168.27.0/24192.168.27.0/24

L P = 200 L P = 300


L P

P BGP

2

A

192.168.27.0/24

10 GE1 GE192.168.27.0/24192.168.27.0/24

P

1/E1192.168.27.0/24

1/E1192.168.27.0/24

B C

R1 R2


4/18


S:D AS

M BGP

AS

S AS


C AS

124 44 13 200 ( 100)

[edit policy-options]

as-path look-for-path “124 44 13”

policy-statement check-the-path {

term got-path {

from as-path look-for-path;

then {

local-preference 200;

accept;

}

}

}


5/18


B , ?B R1 R2 1000 IBGP

( ) export

D R1 R2 ?

172.17/16

172.17/16

172.17/16

LP = 1000

172.17/16

LP = 1000172.17/16

LP = 1000

R2

R1

R3


IBGP , R1 R2 A R2 1000

R1 R2 R2

A

172.17/16

172.17/16

172.17/16

LP = 1000

172.17/16

LP = 1000

172.17/16

LP = 1000

R2

R1

R3


6/18


BGP () BGP

()

A

S

AS ( )

IP ( ?)

, ,

BGP


(1 2)

E

O

C

I ,


7/18


(2 2)

M

C ,

R

AS

AS

R ( ,

200:666)

A AS 0 65535 : 000000000

00000FFFF 0FFFF0000 0FFFFFFFF


:

N (0FFFFFF01):

( AS),

N (0FFFFFF02):

BGP

N (0FFFFFF03):

BGP ( AS)

N

N AS

N

O


8/18


R

AS 1AS 1AS 1AS 1

AS 65000AS 65000AS 65000AS 65000

AS2AS2AS2AS2


R AS

AS 1AS 1AS 1AS 1

AS 65000AS 65000AS 65000AS 65000

AS2AS2AS2AS2


9/18


R AS

AS 1AS 1AS 1AS 1

AS 65000AS 65000AS 65000AS 65000

AS2AS2AS2AS2


AS 2 , I /17 ?

A /16 /17 /17

172.17.0/17

172.17.128/17

172.17/16

AS1 AS2

I

172.17/16

172.17.0/17 (N )

172.17/16

172.17.128/17 (N )


10/181111


AS 2

C

AS 20

AS 1

172.17.144/20

172.17.144/20 (NE )

172.17/16

172.17.144/20

172.17/16

172.17.144/20

172.17.144/20

172.31/16

172.17/16

172.31/16

172.31/16

I172.17/16

172.31/16


C AS 1 AS 2

R

AS 2AS 1

1:60 = L 60

172.17.64/18

172.20.128/18 2:70 = L 70

172.17/16 172.20/16

172.17.64/18

172.20/16 1:60

172.20.128/18

172.17/16 2:70

172.17.64/18

172.20.128/18

172.20/16172.17/16

172.17/16

172.20/16

I

CAS 20


11/181111


C BGP AS AS AS

C

AS

, AS!

N ISP #1

N ISP #2

S ISP

N #1

R1

N #1

S ISP R2

N #1 : NOS ISP : ES


C [edit policy-options]

M community-ids AND[edit policy-options]

community name members [community-ids];

C ID :•as-number:community-value

C ID :

• no-export• no-advertise

• no-export-subconfed

A , ,


12/181111


L user@router> show route 182.168.0/24192.168.0.0/24 (2 entries, 1 announced)

Communities: 64512:567 100:20 50:70 1234:66


policy-statement community-actions {

term add-a-community

then community add test-comm;

}

}

community test-comm members 65001:1234;

user@router> show route 182.168.0/24

192.168.0.0/24 (2 entries, 1 announced)

Communities: 64512:567 100:20 50:70 1234:66 65001:1234


R

user@router> show route 182.168.0/24192.168.0.0/24 (2 entries, 1 announced)

Communities: 64512:567 100:20 50:70 1234:66




then community delete test-comm;

}

}



Communities: 100:20 50:70 1234:66


13/181111


R ALL

user@router> show route 182.168.0/24192.168.0.0/24 (2 entries, 1 announced)

Communities: 64512:567 100:20 50:70 1234:66




then community set test-comm;

}

}



Communities: 65001:1234


1

C customers

S MED 20

S BGP 200 ( 100)


community customers members [56:2379 23:46944];

policy-statement from-customers {

from community customers;

then {

metric 20;

local-preference 200;next policy;

}

}


14/181111


2

C my-acceptR /19 C A, /16

C B, /24 C C

[edit policy-options]community my-accept members 567:1;policy-statement drop-specifics {

term drop-specifics {from {

route-filter 0.0.0.0/1 upto /19 {community add my-accept;next policy;

}route-filter 128.0.0.0/2 upto /16 {

community add my-accept;next policy;

}route-filter 192.0.0.0/3 upto /24 {

community add my-accept;next policy;

}}

}then reject;

}


S ,

AS

B ,

,

( * )


community wild-match members “*:*”;. . .

policy-statement delete-all-communities {

term all-gone {

then community delete wild-match;

}

}


15/181111


S (*) (.)

AS

AS

(.*)

E :

A AS: as-number :*

F , 600:* AS 600

A AS : *:community-value

F ,*:20 20 AS

A 3

F ,1111:50.0 5000, 5010, 5020, . 5090

AS 1111


(1 2)user@router> show route community *:20 terse

inet.0: 123 destinations, 123 routes (123 active, 0 holddown, 0 hidden)

+ = Active Route, - = Last Active, * = Both

A Destination P Prf Metric 1 Metric 2 Next hop AS path

* 192.168.128.0/24 S 5 5 Reject

user@router> show route community *:20 detail



192.168.128.0/24 (1 entry, 1 announced)

*Static Preference: 5

Next hop type: RejectState:

Age: 3d 6:07:37 Metric: 5

Task: RT

Announcement bits (3): 0-KRT 1-BGP.0.0.0.0+179 5-Aggregate

AS path: I

Communities: 1:20


16/1811


(2 2)

user@router> show configuration policy-options

policy-options {

community community-1 members 1:20;

}

user@router> show route community-name community-1 detail



192.168.128.0/24 (1 entry, 1 announced)

*Static Preference: 5

Next hop type: Reject

State:

Age: 3d 6:07:37 Metric: 5

Task: RT

Announcement bits (3): 0-KRT 1-BGP.0.0.0.0+179 5-AggregateAS path: I

Communities: 1:20


C

C ( AS )

F term operator

R (^) ($) ,

show route

• show route community regex

• community match-this members regex


17/18


, M

M

, M

* M 0 , 0,

+ M 1 , 1,

? M 0 1 , 0,1

M

M

$ M M

( ),() ,


C

: R: M:

AS 56 78 ((56)(78)):(.*)$ 56:1000,

78:65000

AS 56 2 56:(2.*)$ 56:234, 56:2,

56:222

AS

5, 7, 9

(.*):(.*579)$ 1234:5,

78:2357,

34:65005

AS 56 78,

2

2 8

((56)(78)):(2.*28)$ 56:22,

56:21197,

78:2678


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D ?

AS 105, 207, 309

4 5 1

O, 2, 5, 6

O, 3, 4, 7, 9

"^((105)|(207)|(309)):((1.{3,4})|([256].*)|

(.*[3479]))$"

08 BGP Attributes and Policy LocalPref Communities

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