bgp community parametri and config-example application
09.01 2020 | by massimilianobgp community parametri Sono implementate come route-tag, usate per: ADVERTISEMENT POLICY FILTERING POLICY BEST PATH SELECTION POLICY […]
https://www.ingegnerianetworking.com/wp-content/uploads/2020/01/bgp-community-example-1-5ac.png
bgp community parametri
Sono implementate come route-tag, usate per:
ADVERTISEMENT POLICY
FILTERING POLICY
BEST PATH SELECTION POLICY
WELL KNOW Community
NO-EXPORT: No Advertisement to EBGP Peers
NO-ADVERTISE: No Advertisement to both EBGP and IBGP Peers
NO-EXPORT -SUBCONF (LOCAL-AS): No Advertisement to Confederation EBGP Peers
Nota:
Il setting è fatto direttamente in route-map
Il matching è fatto via community-list di tipo standard oppure expanded.
Example:
ip-community-list standard 400:1 permit 400:1
ip-community-lit standard 400:2 permit 400:2
!
route-map TO-IN permit 10
match community 400:1
set as-path prepend 400
!
route-map TO-IN permit 20
match community 400:2
set as-path prepend 400 400 400
!
router bgp 400
neighbor 155.28.0.4 route-map TO-IN out
# sul router originatore dell’annuncio:
route-map SET -COMM
set community 400:2
!
router bgp 400 network 155.28.28.0 mask 255.255.255.0 route-map SET -COMM
ESEMPIO DI APPLICAZIONE COMMUNITY
Le community BGP, quindi, sono dei tag con determinati valori che possono essere propagati ai peer neighbors, i quali a seconda del valore di community ricevuto intraprendono delle azioni per determinare politiche di routing.
L’invio di community BGP deve essere esplicitamente indicato, assegnate da route-map e referenziate sempre da route-map:
router bgp < as >
neighbor < ip_address_peer > remote as < as_remote >
neighbor < ip_address_peer > send-community
neighbor < ip_address_peer > route-map assegna-community out
!
access-list < num > permit ip < source-subnet > < destination-subnet >
!
route-map assegna-community permit 10
match ip address < acl_num >
set community AS:NN
!
!
ip community list 1 permit AS:NN
!
route-map referenzia-community permit 10
match community 1
set local-preference 150
ESEMPIO GRAFICO DI APPLICAZIONE COMMUNITY:
CE
access-list 101 permit ip host 10.10.10.0 host 255.255.255.255
access-list 102 permit ip host 20.20.20.0 host 255.255.255.255
!
route-map to-PE1 permit 10
match ip address 101
set community 100:250
!
route-map to-PE1 permit 20
match ip address 102
set community 100:150
!
route-map to-PE2 permit 10
match ip address 102
set community 100:250
!
route-map to-PE2 permit 20
match ip address 101
set community 100:150
!
router bgp 65000
router-id < loopback0 >
network 10.10.10.0 mask 255.255.255.0
network 20.20.20.0 mask 255.255.255.0
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 send-community
neighbor 1.1.1.1 route-map to-PE1 out
neighbor 2.2.2.1 remote-as 100
neighbor 2.2.2.1 send-community
neighbor 2.2.2.1 route-map to-PE2 out
PE1:
ip bgp community new-format
!
ip community-list 101 permit 100:250
ip community-list 102 permit 100:150
!
route-map from-ce permit 10
match community 101
set local-preference 250
!
route-map from-ce permit 20
match community 102
set local-preference 150
!
router bgp 100
router-id < loopback0 >
neighbor 1.1.1.2 remote-as 65000
neighbor 1.1.1.2 send-community
neighbor 1.1.1.2 route-map from-ce in
PE2:
ip bgp community new-format
!
ip community-list 101 permit 100:150
ip community-list 102 permit 100:250
!
route-map from-ce permit 10
match community 1
set local-preference 150
!
route-map from-ce permit 20
match community 2
set local-preference 250
!
router bgp 100
router-id < loopback0 >
neighbor 2.2.2.2 remote-as 65000
neighbor 2.2.2.2 send-community
neighbor 2.2.2.2 route-map from-ce in