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doc: cleanup community list docs more
Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>
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Quentin Young
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doc/user/bgp.rst
166
doc/user/bgp.rst
@ -1034,67 +1034,71 @@ is 4 octet long. The following format is used to define the community value.
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it is considered as external BGP peer, so the route will not be announced to
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the peer.
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When BGP communities attribute is received, duplicated communities value in the
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communities attribute is ignored and each communities values are sorted in
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numerical order.
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When the communities attribute is received duplicate community values in the
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attribute are ignored and value is sorted in numerical order.
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.. _bgp-community-lists:
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Community Lists
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^^^^^^^^^^^^^^^
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Community lists are user defined lists of community attribute values. These
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lists can be used for matching or manipulating the communities attribute in
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UPDATE messages.
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BGP community list is a user defined BGP communities attribute list. BGP
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community list can be used for matching or manipulating BGP communities
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attribute in updates.
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There are two types of community list:
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There are two types of community list. One is standard community list and
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another is expanded community list. Standard community list defines communities
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attribute. Expanded community list defines communities attribute string with
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regular expression. Standard community list is compiled into binary format when
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user define it. Standard community list will be directly compared to BGP
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communities attribute in BGP updates. Therefore the comparison is faster than
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expanded community list.
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standard
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This type accepts an explicit value for the atttribute.
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expanded
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This type accepts a regular expression. Because the regex must be
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interpreted on each use expanded community lists are slower than standard
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lists.
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.. index:: ip community-list standard NAME permit|deny COMMUNITY
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.. clicmd:: ip community-list standard NAME permit|deny COMMUNITY
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This command defines a new standard community list. COMUNITY is
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communities value. The COMUNITY is compiled into community structure. We
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can define multiple community list under same name. In that case match will
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happen user defined order. Once the community list matches to communities
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attribute in BGP updates it return permit or deny by the community list
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definition. When there is no matched entry, deny will be returned. When
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COMUNITY is empty it matches to any routes.
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This command defines a new standard community list. ``COMMUNITY`` is
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communities value. The ``COMMUNITY`` is compiled into community structure.
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We can define multiple community list under same name. In that case match
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will happen user defined order. Once the community list matches to
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communities attribute in BGP updates it return permit or deny by the
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community list definition. When there is no matched entry, deny will be
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returned. When ``COMMUNITY`` is empty it matches to any routes.
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.. index:: ip community-list expanded NAME permit|deny LINE
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.. clicmd:: ip community-list expanded NAME permit|deny LINE
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.. index:: ip community-list expanded NAME permit|deny COMMUNITY
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.. clicmd:: ip community-list expanded NAME permit|deny COMMUNITY
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This command defines a new expanded community list. COMUNITY is a
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string expression of communities attribute. COMUNITY can be a
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regular expression (:ref:`bgp-regular-expressions`) to match
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the communities attribute in BGP updates.
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This command defines a new expanded community list. ``COMMUNITY`` is a
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string expression of communities attribute. ``COMMUNITY`` can be a regular
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expression (:ref:`bgp-regular-expressions`) to match the communities
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attribute in BGP updates.
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.. index:: no ip community-list NAME
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.. clicmd:: no ip community-list NAME
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.. deprecated:: 5.0
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It is recommended to use the more explicit versions of this command.
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.. index:: no ip community-list standard NAME
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.. clicmd:: no ip community-list standard NAME
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.. index:: ip community-list NAME permit|deny COMMUNITY
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.. clicmd:: ip community-list NAME permit|deny COMMUNITY
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.. index:: no ip community-list expanded NAME
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.. clicmd:: no ip community-list expanded NAME
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When the community list type is not specified, the community list type is
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automatically detected. If ``COMMUNITY`` can be compiled into communities
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attribute, the community list is defined as a standard community list.
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Otherwise it is defined as an expanded community list. This feature is left
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for backward compatibility. Use of this feature is not recommended.
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These commands delete community lists specified by NAME. All of
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community lists shares a single name space. So community lists can be
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removed simply specifying community lists name.
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.. index:: show ip community-list
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.. clicmd:: show ip community-list
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.. index:: no ip community-list [standard|expanded] NAME
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.. clicmd:: no ip community-list [standard|expanded] NAME
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.. index:: show ip community-list NAME
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.. clicmd:: show ip community-list NAME
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Deletes the community list specified by ``NAME``. All community lists share
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the same namespace, so it's not necessary to specify ``standard`` or
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``expanded``; these modifiers are purely aesthetic.
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This command displays current community list information. When NAME is
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specified the specified community list's information is shown.
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.. index:: show ip community-list [NAME]
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.. clicmd:: show ip community-list [NAME]
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Displays community list information. When ``NAME`` is specified the
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specified community list's information is shown.
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::
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@ -1126,43 +1130,28 @@ is called as named community lists.
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.. index:: ip community-list (1-99) permit|deny COMMUNITY
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.. clicmd:: ip community-list (1-99) permit|deny COMMUNITY
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This command defines a new community list. (1-99) is standard
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community list number. Community list name within this range defines
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standard community list. When `community` is empty it matches to
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any routes.
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This command defines a new community list. The argument to (1-99) defines
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the list identifier.
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.. index:: ip community-list (100-199) permit|deny COMMUNITY
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.. clicmd:: ip community-list (100-199) permit|deny COMMUNITY
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This command defines a new community list. (100-199) is expanded
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community list number. Community list name within this range defines
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expanded community list.
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.. index:: ip community-list NAME permit|deny COMMUNITY
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.. clicmd:: ip community-list NAME permit|deny COMMUNITY
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When community list type is not specified, the community list type is
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automatically detected. If COMMUNITY can be compiled into communities
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attribute, the community list is defined as a standard community list.
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Otherwise it is defined as an expanded community list. This feature is left
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for backward compatibility. Use of this feature is not recommended.
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This command defines a new expanded community list. The argument to
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(100-199) defines the list identifier.
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.. _bgp-using-communities-in-route-map:
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Using Communities in Route Maps
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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In Route Map (:ref:`route-map`), we can match or set BGP
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communities attribute. Using this feature network operator can
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implement their network policy based on BGP communities attribute.
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In :ref:`route-map` we can match on or set the BGP communities attribute. Using
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this feature network operator can implement their network policy based on BGP
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communities attribute.
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Following commands can be used in Route Map.
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The ollowing commands can be used in route maps:
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.. index:: match community WORD
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.. clicmd:: match community WORD
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.. index:: match community WORD exact-match
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.. clicmd:: match community WORD exact-match
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.. index:: match community WORD exact-match [exact-match]
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.. clicmd:: match community WORD exact-match [exact-match]
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This command perform match to BGP updates using community list WORD. When
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the one of BGP communities value match to the one of communities value in
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@ -1170,32 +1159,25 @@ Following commands can be used in Route Map.
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happen only when BGP updates have completely same communities value
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specified in the community list.
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.. index:: set community none
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.. clicmd:: set community none
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.. index:: set community <none|COMMUNITY> additive
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.. clicmd:: set community <none|COMMUNITY> additive
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.. index:: set community COMMUNITY
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.. clicmd:: set community COMMUNITY
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This command sets the community value in BGP updates. If the attribute is
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already configured, the newly provided value replaces the old one unless the
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``additive`` keyword is specified, in which case the new value is appended
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to the existing value.
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.. index:: set community COMMUNITY additive
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.. clicmd:: set community COMMUNITY additive
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This command manipulate communities value in BGP updates. When
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`none` is specified as communities value, it removes entire
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communities attribute from BGP updates. When `community` is not
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`none`, specified communities value is set to BGP updates. If
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BGP updates already has BGP communities value, the existing BGP
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communities value is replaced with specified `community` value.
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When `additive` keyword is specified, `community` is appended
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to the existing communities value.
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If ``none`` is specified as the community value, the communities attribute
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is not sent.
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.. index:: set comm-list WORD delete
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.. clicmd:: set comm-list WORD delete
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This command remove communities value from BGP communities attribute.
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The `word` is community list name. When BGP route's communities
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value matches to the community list `word`, the communities value
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is removed. When all of communities value is removed eventually, the
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BGP update's communities attribute is completely removed.
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This command remove communities value from BGP communities attribute. The
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``word`` is community list name. When BGP route's communities value matches
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to the community list ``word``, the communities value is removed. When all
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of communities value is removed eventually, the BGP update's communities
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attribute is completely removed.
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.. _bgp-communities-example:
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@ -2202,12 +2184,12 @@ Example of a session to an upstream, advertising only one prefix to it.
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ip prefix-list pl-allowed-adv seq 5 permit 82.195.133.0/25
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ip prefix-list pl-allowed-adv seq 10 deny any
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A more complex example. With upstream, peer and customer sessions. Advertising
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global prefixes and NO_EXPORT prefixes and providing actions for customer
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routes based on community values. Extensive use of route-maps and the 'call'
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feature to support selective advertising of prefixes. This example is intended
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as guidance only, it has NOT been tested and almost certainly contains silly
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mistakes, if not serious flaws.
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A more complex example including upstream, peer and customer sessions
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advertising global prefixes and NO_EXPORT prefixes and providing actions for
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customer routes based on community values. Extensive use is made of route-maps
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and the 'call' feature to support selective advertising of prefixes. This
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example is intended as guidance only, it has NOT been tested and almost
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certainly contains silly mistakes, if not serious flaws.
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.. code-block:: frr
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