Extended Community Lists

title: Extended Community Lists sidebar: order: 10

You can use extended community lists to filter BGP routes based on the community attribute. The community number consists of a 6-byte value in the aa4:nn format. The first four bytes represent the autonomous system number, and the last two bytes represent a user-defined network number.

When you configure multiple values in the same extended community list statement, all extended community values must match to satisfy the extended community list filter. When you configure multiple values in separate extended community list statements, the first list that matches a condition is processed.

Use extended community lists in a match statement to filter BGP routes based on the extended community attribute.

Transitive—BGP propagates the community attributes across autonomous systems.
Nontransitive—BGP removes community attributes before propagating the route to another autonomous system.

Diagram

Classes

route_control (vxlan.overlay_extensions)

Name	Type	Constraint	Mandatory	Default Value
extended_community_lists	List	`[extended_community_lists]`	No

extended_community_lists (vxlan.overlay_extensions.route_control)

Name	Type	Constraint	Mandatory	Default Value
name	String	Regex: `^[A-Za-z0-9-_]{1,63}$`	Yes
entries	List	`[entries]`	Yes

entries (vxlan.overlay_extensions.route_control.extended_community_lists)

Name	Type	Constraint	Mandatory
seq_number	Integer	min: `1`, max: `4294967294`	Yes
operation	Choice	`permit`, `deny`	Yes
communities	Class	`[communities]`	No

communities (vxlan.overlay_extensions.route_control.extended_community_lists.entries)

Name	Type	Constraint	Mandatory
4byteas_generic	List	`[4byteas_generic]`	No
rmac	List	Any[String[Regex: `^[a-f0-9]{4}.[a-f0-9]{4}.[a-f0-9]{4}$`] or String[Regex: `^[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}$`] or String[Regex: `^[a-f0-9]{2}-[a-f0-9]{2}-[a-f0-9]{2}-[a-f0-9]{2}-[a-f0-9]{2}-[a-f0-9]{2}$`]]	No
rt	List	Any[String[Regex: `^((?!0)[0-9]{1,5}.[0-9]{1,5})$`] or String[Regex: `^((?!0)[0-9]{1,11}.[0-9]{1,5})$`] or String[Regex: `^((25[0-5]\|(2[0-4]\|1\d\|[1-9]\|)\d)\.?){4}$`]]	No
soo	List	Any[String[Regex: `^((?!0)[0-9]{1,5}.[0-9]{1,5})$`] or String[Regex: `^((?!0)[0-9]{1,11}.[0-9]{1,5})$`] or String[Regex: `^((25[0-5]\|(2[0-4]\|1\d\|[1-9]\|)\d)\.?){4}$`]]	No

4byteas_generic (vxlan.overlay_extensions.route_control.extended_community_lists.entries.communities)

Name	Type	Constraint	Mandatory	Default Value
transitive	Boolean	`true`, `false`	Yes
extended_community_number_list	String	Regex: `^([0-9]{1,5}:[0-9]{1,5})$`	Yes

Examples

Example-1

The following example creates and configures a named: extcomm_list-test extended community list that will permit routes only from AS-4byte 65535:40 transitive AND AS-4byte 65535:60 transitive

switch# configure terminal
switch(config)# ip extcommunity-list standard extcomm_list-test seq 10 permit 4byteas-generic transitive 65535:40 4byteas-generic transitive 65535:60

---
vxlan:
  overlay_extensions:
    route_control:
      extended_community_lists:
        - name: extcomm_list-test
          entries:
            - seq_number: 10
              operation: permit
              communities:
                4byteas_generic:
                  - transitive: true
                    extended_community_number_list: 65535:40
                  - transitive: true
                    extended_community_number_list: 65535:60
      groups:
        - name: ExtCommunity_RCtrlGrp
          extended_community_lists:
            - name: extcomm_list-test
      switches:
        - name: netascode-leaf1
          groups:
            - ExtCommunity_RCtrlGrp

Example-2

The following example creates and configures a named: commext extended community list that will permit routes only from AS-4byte 65535:20 AND route target (rt) 2:2 AND with site of origin (soo) 3:3 AND will implicitly deny all other routes:

ip extcommunity-list standard commext seq 10 permit 4byteas-generic transitive 65535:20 rt 2:2 soo 3:3

---
vxlan:
  overlay_extensions:
    route_control:
      extended_community_lists:
        - name: commext
          entries:
            - seq_number: 10
              operation: permit
              communities:
                4byteas_generic:
                  - transitive: true
                    extended_community_number_list: 65535:20
                rt:
                  - 2:2
                soo:
                  - 3:3
      groups:
        - name: ExtCommunity_RCtrlGrp
          extended_community_lists:
            - name: commext
      switches:
        - name: netascode-leaf1
          groups:
            - ExtCommunity_RCtrlGrp