CCIE Learning Note 3---BGP Community attribute Community

Optional delivery

-BGP Communities is a marker for routing entries to ensure continuity of routing filtering and selection

-BGP routers can community the routing entries when redistribution, sending, and receiving routing updates (ROUTE-MAP)

-Depending on the community value, the BGP router can filter incoming or outgoing routing updates or optimize certain routes

-By default, community is stripped when the update route is in progress

The community Balue is split into the parts:

[As-number]:[low-order-16-bits]

As number description Local device

Configuration

Router (config) #

Match condition

Set community Value---100:1//AS100

Router BGP 100

Nei x.x.x.x route-map Map in/out

Neit x.x.x.x send-community//community is not passed by default, this command is used to pass

Call community, action

Router (config) #

IP community-list 1-99 Permit | Deny value

Community-list Standard (1-99): match the value of someone else's hit

Extension (100-199): match with regular expression.

Route-map name Permit|deny

Match Community Clist-number

Set attributes

Experiment:

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AS200 Configuration Federation, R2 R4 in As2000;r5 in AS300

R2 R4 R5IGP running OSPF

R1:

int f1/0

IP Add 12.1.1.1 255.255.255.0

No Shu

int Lo0

IP Add 1.1.1.1 255.255.255.255

Router BGP 100

Nei 12.1.1.1 Remot 200

R2:

int f1/0

IP Add 12.1.1.2 255.255.255.0

No Shu

IP OS 1 A 0

int Lo0

IP Add 2.1.1.1 255.255.255.255

IP OS 1 A 0

int F1/1

IP Add 24.1.1.2 255.255.255.0

No Shu

IP OS 1 A 0

int Lo0

IP Add 2.1.1.1 255.255.255.255

IP OS 1 A 0

Router BGP 2000

BGP Confen ID 200

Nei 4.1.1.1 Remot 2000

Nei 4.1.1.1 up Lo0

Nei 4.1.1.1 next-hop-self

Nei 12.1.1.1 Remot 100

R4: Enable IGP OSPF

Router BGP 2000

BGP Confen ID 200

BGP Confen Peers 3000

Nei 2.1.1.1 Remot 2000

Nei 2.1.1.1 up Lo0

Nei 5.1.1.1 Remot 3000

Nei 5.1.1.1 up Lo0

Nei 5.1.1.1 ebgp-multihop

R5: Enable IGP OSPF

Router BPG 3000

BGP Confen ID 200

BGP Confen Peer 2000

Nei 4.1.1.1 Remot 2000

Nei 4.1.1.1 up Lo0

Nei 4.1.1.1 next-hop-s

Nei 4.1.1.1 Ebgp-multi

Nei 56.1.1.6 Remot 300

R6:router BGP 300

Nei 56.1.1.5 Remot 200

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Configure Community

R1:router BGP 100

NET 1.1.1.1

IP prefix-list 1.1 per 1.1.1.1/32

Route-map com per 10

Match IP Add prefix-list 1.1

Set Commu 100:1

Route-map com per 1000

Router BGP 100

Nei 12.1.1.2 send-community//community is not passed by default, you need to manually configure delivery

R2:sho IP BGP 1.1.1.1//commuity value is not 100:1 format

Conf t

IP bgp-community new-format//configuration display in 100:1 format

Sho IP bgp 1.1.1.1

R2 can be configured by configuring Community-list call 100:1, and set different values

IP community-list 1 per 100:1

Route-map com per 10

Match Community 1

Set Commuity 200:2

Route-map com per 1000

Router BGP 2000

Nei 12.1.1.1 route-map com out

Sho IP bgp 1.1.1.1//At this time Community=200:2, before the 100:1 is overwritten

To overwrite 100:1, you need to add the ROUTE-MAP keyword additive

Route-map com per 10

Set Community 200:2 additive

Sho IP b 1.1.1.1//Can be seen at the same time 100:1 200:2

When a policy is matched to a community value, there are multiple community values in a route, as long as a match can be

R4:

IP community-list 1 per 100:1

Route-map Test per 10

Match Community 1

Set Wei 2000

Can be set by the keyword Exact-match, when there are multiple community, the full match is the line (exact match)

Route-map Test per 10

Match Community 1 exact-match

IP community-list 1 per 100:1 200:2

Sho IP b

Commnity-list can match multiple values

IP commnuity-list 1 per 100:1 200:2

IP commnuity-list 1 per 200:2

Sho IP community-list

CCIE Learning Note 3---BGP Community attribute Community