maximum-prefixes
Syntax
maximum-prefixes prefix-limit <log-interval seconds> <log-only | threshold percentage>;
Hierarchy Level
[edit logical-systems logical-system-name routing-instances routing-instance-name routing-options], [edit logical-systems logical-system-name routing-options], [edit routing-instances routing-instance-name routing-options], [edit routing-options]
Description
Configure a limit for the number of routes installed in a routing table based upon the route prefix.
Using a prefix limit, you can curtail the number of prefixes received from a CE router in a VPN. Prefix limits apply only to dynamic routing protocols and are not applicable to static, programmed, or interface routes.
Static, programmed [that is, programmable routing protocol process (prpd)
configured], and interface routes contribute to the overall route total count
used in the maximum-prefix calculation. The number of such routes affects the
number of dynamic routes that are accepted in to the virtual routing instance.
In the configuration example shown below, if VRF1 contains 98
static routes and 2 interface routes, then a maximum of 900 BGP routes (that is,
1000 - 98 - 2 = 900) are allowed, with a syslog warning shown at a total of 800
dynamic routes, which is 80%.
set routing-instances VRF1 routing-options maximum-prefixes 1000 set routing-instances VRF1 routing-options maximum-prefixes threshold 80
If the number of static, programmed, or interface routes increases, then it can affect the maximum number of dynamic routes that are accepted. Note that the static, programmed, or interface routes are not subject to the configured maximum-prefixes limit and can have a negative or undesired effect on the dynamic routes.
The maximum-prefixes statement is similar to the
maximum-paths statement. The maximum-prefixes
statement limits the number of unique destinations in a routing instance. For
example, suppose a routing instance has the following routes:
OSPF 10.10.10.0/24 ISIS 10.10.10.0/24
These are two routes, but only one destination (prefix). The
maximum-paths limit applies the total number of routes (two).
The maximum-prefixes limit applies to the total number of unique
prefixes (one).
Options
log-interval seconds—(Optional) Minimum time interval (in seconds) between
log messages.
Range: 5 through 86,400
log-only—(Optional) Sets the prefix limit as
an advisory limit. An advisory limit triggers only a warning, and
additional routes are not rejected.
prefix-limit—Maximum number
of route prefixes. If this limit is reached, a warning is triggered
and any additional routes are rejected.
Range: 1 through 4,294,967,295
Default: No default
threshold value—(Optional)
Percentage of the maximum number of prefixes that starts triggering
a warning. You can configure a percentage of the prefix-limit value that starts triggering the warnings.
Range: 1 through 100
When the number of routes reaches the threshold value, routes are still installed into the routing table while warning
messages are sent. When the number of routes reaches the prefix-limit value, then additional routes are rejected.
Required Privilege Level
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.
Release Information
Statement introduced in Junos OS Release 8.0.