Extreme Networks ExtremeWare XOS 10.1, Руководство пользователя

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Switch Protection
ExtremeWare XOS 10.1 Concepts Guide 121
origin egp;
}
}
Policy entries are evaluated in order, from the beginning of the file to the end, as follows:
• If a match occurs, the action in the then statement is taken:
— if the action contains an explicit permit or deny, the evaluation process terminates.
— if the action does not contain an explicit permit or deny, then the action is an implicit permit, and
the evaluation process terminates.
• If a match does not occur, then the next policy entry is evaluated.
• If no match has occurred after evaluating all policy entries, the default action is deny.
Often a policy will have a rule entry at the end of the policy with no match conditions. This entry will
match anything not otherwise processed, so that user can specify an action to override the default deny
action.
The next sections list detailed information about policy match conditions, about matching BGP AS
paths, and about action statements. For information on those subjects, see the following sections:
• “Policy Match Conditions” on page 121
• “Autonomous System Expressions” on page 122
• “Policy Action Statements” on page 124
Policy Match Conditions
Table 23 lists the possible policy entry match conditions.
Table 23: Policy Match Conditions
Match Condition Description
as-path [<as-number>
| <as-path-regular-expression>]; Where <as-number> is a valid Autonomous system number
in the range [1 - 65535].
<as-path-regular-expression> is a multi-character regular
expression (with 2-byte unsigned Integer being an Atom).
Regular expression will consist of the AS-Numbers and
various regular expression symbols. Regular expressions
must be enclosed in double quotes ("").
community [no-advertise | no-export |
no-export-subconfed | number <community_num> |
<community_regular_expression> |
<as_num> : <num>]; "no-advertise", "no-export" and "no-export-subconfed" are
the standard communities defined by RFC.
<community_num> is a four byte unsigned integer,
<as_num> is a two byte AS-Number and <num> is the
2-bytes community number.
Community regular expression is a multi-character regular
expression (with four byte unsigned integer being an Atom).
Regular expression is enclosed in double quotes ("").
med <number>; <number> is a four byte unsigned integer.
next-hop [<ipaddress> {<ipaddress1> <ipaddress2>
<ipaddress3> ..} | <ipaddress-regular-expression>]; <ipaddress> is a valid IP address in dotted decimal format.
User can supply multiple IP addresses (separated by
space) to match against the next hop.