Examples: Configuring the Community Attribute

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

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:

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

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

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

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 lcl 20x-high members "^20 [ 1-5 ] : 120$";

  policy-statement in-customer {

  term term1 {

  from {

  protocol bgp;

  community lcl 20x-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;

  }

  }

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