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
####################################################
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