Examples: Configuring BGP Communities as Routing Policy Match Conditions

Create a community named dunedin and apply it in a routing policy statement:

[edit]policy-options {community dunedin members [ 56:2379 23:46944 ];policy-statement from-dunedin {from community dunedin;then {metric 2;preference 100;next policy;}}}

The preceding example modifies the metric and preference for routes that contain members of community dunedin only.

Note: You cannot set or add a community in a policy whose members use regular expressions or a wildcard.

Delete a particular community from a route, leaving remaining communities untouched:

[edit]policy-options {community dunedin members 701:555;policy-statement delete-dunedin {then {community delete dunedin;}}}

Remove any community from a route with the AS number of 65534 or 65535:

[edit]policy-options {community my-as1-transit members [ 65535:10 65535:11 ];community my-as2-transit members [ 65534:10 65534:11 ];community my-wild members [ 65534:* 65535:* ];policy-statement delete-communities {from {community [ my-as1-transit my-as2-transit ];}then {community delete my-wild;}}}

Match the set of community members 5000, 5010, 5020, 5030, and so on up to 5090:

[edit]policy-options {community customers members "^1111:50.0$";policy-statement advertise-customers {from community customers;then accept;}}

Reject routes that are longer than /19 in Class A space, /16 in Class B space, and /24 in Class C space:

[edit policy-options]community auckland-accept members 555:1;policy-statement drop-specific-routes {from {route-filter 0.0.0.0/1 upto /19 {community add auckland-accept;next policy;}route-filter 172.16.0.0/2 upto /16 {community add auckland-accept;next policy;}route-filter 192.168.0.0/3 upto /24 {community add auckland-accept;next policy;}}then reject;}

In the preceding example, for routes that are not rejected, the tag auckland-accept is added.

Create routing policies to handle peer and customer communities. This example does the following:

Customer routes that match the attributes defined in the lcl20x-low communities, for example, lcl201-low, are accepted and their local preference is changed to 80.
Customer routes that match the attributes defined in the lcl20x-high communities, for example, lcl201-high, are accepted and have their local preference changed to 120.
Internal routes that match the attributes defined in the internal20x communities, for example, internal201, are rejected and not advertised to customers.
Routes received from a peer are assigned a metric of 10 and the community defined in peer201.
Routes that match the attributes defined in the prepend20x-x communities, for example, prepend201-1, prepend201-2, or prepend201-3, are sent to peers and have the AS number 201 prepended the specified number of times.
Routes that match the attributes defined in the peer20x, custpeer20x, and internal20x communities, for example, peer201, custpeer201, or internal201, respectively, are rejected and not advertised to peers.
[edit]policy-options {community internal201 members 201:112;community internal202 members 202:112;community internal203 members 203:112;community internal204 members 204:112;community internal205 members 205:112;community peer201 members 201:555;community peer202 members 202:555;community peer203 members 203:555;community peer204 members 204:555;community peer205 members 205:555;community custpeer201 members 201:20;community custpeer202 members 202:20;community custpeer203 members 203:20;community custpeer204 members 204:20;community custpeer205 members 205:20;community prepend201-1 members 201:1;community prepend202-1 members 202:1;community prepend203-1 members 203:1;community prepend204-1 members 204:1;community prepend205-1 members 205:1;community prepend201-2 members 201:2;community prepend202-2 members 202:2;community prepend203-2 members 203:2;community prepend204-2 members 204:2;community prepend205-2 members 205:2;community prepend201-3 members 201:3;community prepend202-3 members 202:3;community prepend203-3 members 203:3;community prepend204-3 members 204:3;community prepend205-3 members 205:3;community lcl201-low members 201:80;community lcl202-low members 202:80;community lcl203-low members 203:80;community lcl204-low members 204:80;community lcl205-low members 205:80;community lcl20x-high members "^20 [ 1-5 ] : 120$";policy-statement in-customer {term term1 {from {protocol bgp;community lcl20x-high;}then {local-preference 80;accept;}}term term2 {from {protocol bgp;community [ lcl201-high lcl202-high lcl203-high lcl204-high lcl205-high ];}then local-preference 120;}then next policy;}policy-statement out-customer {term term1 {from {protocol bgp;community [internal201 internal202 internal203 internal204 internal205];}then reject;}then next policy;}policy-statement in-peer {from protocol bgp;then {metric 10;community set peer201;}}policy-statement out-peer {term term1 {from {protocol bgp;community [ prepend201-1 prepend202-1 prepend203-1 prepend204-1 prepend205-1 ];}then as-path-prepend 201;}term term2 {from {protocol bgp;community [ prepend201-2 prepend202-2 prepend203-2 prepend204-2 prepend205-2 ];}then as-path-prepend "201 201";}term term3 {from {protocol bgp;community [ prepend201-3 prepend202-3 prepend203-3 prepend204-3 prepend205-3 ];}then as-path-prepend "201 201 201";}term term4 {from {protocol bgp;community [ peer201 peer202 peer203 peer204 peer205 custpeer201 custpeer202 custpeer203 custpeer204 custpeer205 internal201 internal202 internal203 internal204 internal205 ];}then reject;}then next policy;}}