Route policies

Multiple policy-statement names can be specified in the CLI commands that attach route policies to specific functions. A chain of routing policies is created if a list of two or more policy names is specified in the CLI command. Route policy chaining allows complex route processing logic to be broken into smaller components. This enables the reuse of common functions and facilitates the process of amending and updating route control logic as required.

Each route is evaluated against a policy chain as follows.

1. The route is evaluated against the first listed policy. If the route matches an entry with action next-policy, or the route matches no entry and the default action is next-policy (or there is no default action specified at all), the evaluation continues into the second policy.

2. The route is evaluated against the second listed policy. If the route matches an entry with next-policy as the action or a default action of next-policy applies, the evaluation continues to the third policy.

3. The sequential evaluation of policies continues until the route is accepted or rejected by an entry or explicit default action.

In addition to policy chaining, the SR OS also supports policy logical expressions that enable applications to use complex multiple policy statements. A policy logical expression can be used as a standalone expression or as part of a policy chain. Each policy chain supports a maximum of one logical expression. The logical expression is usually the first element of the policy chain; however, it can appear in a non-initial position as long as its length does not exceed 64 characters.

A route policy logical expression is a string composed of logical operators (keywords AND, OR and NOT), up to 16 route policy names (each up to 64 characters in length and delimited by brackets ( ) and square brackets [ ] to group sub-expressions (with up to three levels of nesting)). The total length of the route policy expression cannot exceed 900 characters.

The following are examples of valid logical expressions in the SR OS CLI syntax:

• ‟NOT [policyA]”

• ‟[policyA] AND [policyB] OR [policyC]”

• ‟NOT ([policyA] OR [policyB] OR [policyC])”

The final result of a route policy evaluation against a logical expression is TRUE or FALSE. The SR OS rules for policy evaluation are as follows.

• If the expression includes a NOT operator followed by a sub-expression in brackets, the expression is flattened using De Morgan's rule.

  For example, the expression ‟NOT ([policyA] OR [policyB] OR [policyC])” is flattened to: ‟(NOT [policyA]) AND (NOT [policyB]) AND (NOT [policyC])”.

• The usual rules of precedence apply: NOT is the highest priority, then AND, then OR.

• The use of ‟NOT <expression>” negates the TRUE/FALSE result of the expression.

• Where the logic is ‟(<expression1>) AND (<expression2>)”, if expression1 is FALSE, the result is FALSE and expression2 is not evaluated. If expression1 is TRUE, expression2 is then evaluated. The final result is TRUE only if both expressions are TRUE.

• Where the logic is ‟(<expression1>) OR (<expression2>)”, if expression1 is TRUE, the result is TRUE and expression2 is not evaluated. If expression1 is FALSE, expression2 is then evaluated. The final result is TRUE if either expression is TRUE.

• Evaluation of a policy termination is as follows:

  • MD-CLI

    If the evaluation of a policy terminates with an accept, next-entry or next-policy action, the result is TRUE. If the evaluation of a policy terminates with an reject or drop action, the result is FALSE. If a route matches no entry in a policy and there is no specified default action, the implied default action is next-policy; if there is no next policy, this translates to the default action for the protocol.

  • classic CLI

    If the evaluation of a policy terminates with an accept, next-entry or next-policy action, the result is TRUE. If the evaluation of a policy terminates with an reject or drop action, the result is FALSE. If a route matches no entry in a policy and there is no specified default action, the implied default action is next-policy; if there is no next policy, this translates to the default action for the protocol.

  If the evaluation of a policy terminates with an accept, next-entry or next-policy action, the result is TRUE. If the evaluation of a policy terminates with an reject or drop action, the result is FALSE. If a route matches no entry in a policy and there is no specified default action, the implied default action is next-policy; if there is no next policy, this translates to the default action for the protocol.

• When a route is evaluated against a policy contained in a logical expression, the route property changes (such as MED, local preference, communities) made by the matching entry or default action apply cumulatively to the route. The result of a cumulative change is that a policy evaluated later in the logical expression (or later in the entire policy chain) may undo or reverse prior changes. A later policy in the logical expression (or policy chain) may also match a route on the basis of route properties that were modified by earlier policies.

When evaluation of the logical expression is complete, the final TRUE or FALSE result is translated back to a traditional action. The FALSE value is translated to action reject; the TRUE value is translated to action accept, action next-policy or action next-entry to match the action of the last policy that produced the TRUE result.

It is possible to reference a routing policy from within another routing policy to construct powerful subroutine based policies.

Up to the three levels of subroutine calls are supported. Policy subroutines produce a final result of TRUE or FALSE through matching and policy entry actions. A policy entry action of ‛accept’ evaluates to TRUE, and a policy entry action of reject evaluates to FALSE.

When using next-policy action state in the subroutine, the match value is defined by the default action behavior. The action is protocol-dependent. See Default action behavior for information about the default actions that are applied during packet processing.

If a match is not found during the evaluation of one or more routing policies, the final evaluation returns the accept or the reject provided by the default behavior based on the policy type (import or export) and the destination and/or source protocol.

Users can evaluate a routing policy against a BGP neighbor, routing context, or individual prefix before applying the policy to the neighbor or routing context. Use the following command to show what modifications are made by a policy.

show router bgp policy-test plcy-or-long-expr

show router bgp policy-test plcy-or-long-expr

In the classic CLI, users can set an exclusive lock on policy edit sessions using the following command.

configure router policy-options exclusive-lock

When the exclusive flag is set by a user that is editing policy, other users (console or SNMP) are restricted from being able to begin, edit, commit, or abort policy. An administrative override is made available to reset the exclusive flag in the event of a session failure.

The default action of a policy applies to a route when the route does not match any of the entries of the policy. If a policy does not have any match entries, all routes are subject to the default action. If no default action is specified and the policy is the last one in a chain of policies, the default action is determined by the protocol that called the policy.

If a default action is defined for one or more of the configured route policies, then the default action is handled as follows.

• The default action can be set to all available action states including accept, reject, next-entry, and next-policy.

• If the action states accept or reject, the policy evaluation terminates and the appropriate result is returned.

• If a default action is defined and no matches occurred with the entries in the policy, then the default action is used.

• If a default action is defined and one or more matches occurred with the entries of the policy, then the default action is not used.

The Route Table Manager does not inherently restrict any IP prefixes from the forwarding table, but individual routing protocols may not accept prefixes that are not globally routable.

Route damping is a controlled acceptance of unstable routes from BGP peers so that any ripple effect caused by route flapping across BGP AS border routers is minimized. The purpose is to delay the use of unstable routes (flapping routes) to forward data and advertisements until the route stabilizes.

Nokia’s implementation of route damping is based on the following:

• Figure of Merit

  A route is assigned a Figure of Merit (FoM), which is proportional to the frequency of flaps. FoM should be able to characterize route behavior over a period of time.

• route flap

  A route flap is not limited to the withdrawn route. It also applies to any change in the AS path or the next-hop of a reachable route. A change in AS path or next-hop indicates that the intermediate AS or the route-advertising peer is not suppressing flapping routes at the source or during the propagation. Even if the route is accepted as a stable route, the data packets destined for the route could experience unstable routing because of the unstable AS path or next-hop.

• suppress threshold

  The threshold is a configured value such that, when exceeded, the route is suppressed and not advertised to other peers. The state is considered to be down from the perspective of the routing protocol.

• reuse threshold

  When the FoM value falls below a configured reuse threshold and the route is still reachable, the route is advertised to other peers. The FoM value decays exponentially after a route is suppressed. This requires the BGP implementation to decay thousands of routes from a misbehaving peer.

The two events that could trigger the route flapping algorithm are:

• route flapping

  If a route flap is detected within a configured maximum route flap history time, the route FoM is initialized and the route is marked as a potentially unstable route. Every time a route flaps, the FoM is increased and the route is suppressed if the FoM crosses the suppress threshold.

• route reuse timer trigger

  The FoM of a suppressed route decays exponentially. When it crosses the reuse threshold, the route is eligible for advertisement if it is still reachable.

If the route continues to flap, the FoM, with respect to time scale, looks like a sawtooth waveform with the exponential rise and decay of FoM. To control flapping, the following parameters can be configured:

• half-life

  The half-life value is the time, expressed in minutes, required for a route to remain stable in order for one half of the FoM value to be reduced. For example, if the half-life value is 6 (minutes) and the route remains stable for 6 minutes, the new FoM value is 3. If another 6 minutes passes and the route remains stable, the new FoM value is 1.5.

  Use the following command to configure the half-life value:

  • MD-CLI

    configure policy-options damping half-life

  • classic CLI

    configure router policy-options damping half-life

• max-suppress

  The maximum suppression time, expressed in minutes, is the maximum amount of time that a route can remain suppressed.

  Use the following command to configure the maximum suppression time:

  • MD-CLI

    configure policy-options damping max-suppress

  • classic CLI

    configure router policy-options damping max-suppress

• suppress

  If the FoM value exceeds the configured integer value, the route is suppressed from use or inclusion in advertisements.

  Use the following command to configure the suppression value:

  • MD-CLI

    configure policy-options damping suppress

  • classic CLI

    configure router policy-options damping suppress

• reuse

  If the suppress value falls below the configured reuse value, the route can be reused.

  Use the following command to configure the reuse value:

  • MD-CLI

    configure policy-options damping reuse

  • classic CLI

    configure router policy-options damping reuse

Nokia’s implementation of BGP uses route policies extensively. The implied or default route policies can be overridden by customized route policies. The default BGP properties, with no route policies configured, behave as follows:

• accept all BGP routes into the RTM for consideration

• announce all used BGP learned routes to other BGP peers

• announce none of the IGP, static, or local routes to BGP peers

The following figure shows OSPF, which applies routing policies at the edge of the protocol, to control only the routes that are announced to or accepted from the RTM.

Occasionally, BGP routes may be re-advertised from BGP into OSPF and IS-IS. OSPF export policies (policies that control which routes are exported to OSPF) are not handled by the main OSPF task. They are handled by a separate task or an RTM task that filters the routes before they are presented to the main OSPF task.

With triggered policy enabled, deletion and re-addition of a peer after making changes to an export policy causes the new updates to be sent out to all peers.

The triggered policy feature is not honored if a new peer is added to BGP. An update with the old policy is sent to the newly added peer. The new policy does not get applied to the new peer until the peer is flapped.

With triggered policy enabled, if a new BGP/static route comes in, a new addition or the modification of an export policy causes the updates to send out dynamically to all peers with the new or modified export policy.

When multiple peers (for example, P1, P2 and P3) share the same export policy, any modifications to the export policy followed the following command on one of the peers, for instance P1, sends out routes to P1 only according to newly modified policy.

clear router bgp neighbor soft

Though routes with a newly modified policy are not sent to other peers (P2 and P3) as there were no issues the clear router bgp neighbor command with the soft command option on these peers, RIB-OUT shows that new routes with the modified policy are sent to all the peers. RIB-IN on peers P2 and P3 are shown correctly.

The triggered policy is not honored if a new peer is added to BGP. An update with the old policy is sent to the newly added peer. The new policy is not applied to the new peer until the peer is flapped.

With the triggered policy feature enabled, if a new BGP/static route comes in, the new addition or modification of an export policy causes the updates to be sent out dynamically to all peers with the new or modified export policy.

When multiple peers, such as P1, P2, and P3, share the same export policy, any modifications to the export policy followed by using the clear router bgp neighbor command with the soft command option on one of the peer P1s, send out routes to P1 only according to the newly modified policy. Though routes with the newly modified policy are not sent to other peers (P2 and P3) as there are no issues using the clear router bgp neighbor command with the soft command option on these peers, RIB-OUT shows that the new routes with the modified policy are sent to all the peers. RIB-IN on peers P2 and P3 are shown correctly.

This feature sets MED to the IGP cost of a route exported into BGP as an action in route policies. The following command supports this feature at the global BGP level.

configure router bgp med-out
configure service vprn bgp med-out

The following command supports this feature at the BGP group level.

configure router bgp group med-out
configure service vprn bgp group med-out

Additionally, the following command supports this feature at the BGP neighbor level:

• MD-CLI

  configure router bgp neighbor med-out
  configure service vprn bgp neighbor med-out

• classic CLI

  configure router bgp group neighbor med-out
  configure service vprn bgp group neighbor med-out

However, the preceding commands lack per-prefix granularity. Alternatively, use the command options in the following context to set the MED to a fixed number or add or subtract a fixed number from the received MED, as well as set the IGP cost option:

• MD-CLI

  configure policy-options policy-statement entry action metric

• classic CLI

  configure router policy-options policy-statement entry action metric

Configuring the set command option to use igp (when used in a BGP export policy), has the same effect as configuring the med-out command to use igp-cost, except that it applies only to the routes matched by the policy entry.

The effect configuring the set command option to igp depends on the route type and policy type, as described in the following table.

A BGP policy can call another policy (subroutine) and that subroutine can call another subroutine, and so on. This facilitates re-usability of common logic and a structured approach to writing BGP policies. Up to three levels of subroutine are supported.

This feature adds the flexibility to attach a route policy to the BGP next-hop resolution process; it also allows a route policy to be associated with the optional BGP peer-tracking function. BGP next-hop resolution is a fundamental part of BGP protocol operation; it determines the best matching route (or tunnel) for the BGP next-hop address and uses information about this resolving route in the best path selection algorithm and to program the forwarding table. Attaching a policy to BGP next-hop resolution provides more control over which IP routes in the routing table can become resolving routes. Similar flexibility is also available for BGP peer-tracking, which is an optional feature that allows the session with a BGP neighbor to be taken down if there is no IP route to the neighbor address or if the best matching IP route is rejected by the policy.

The following are known limitations of the policy reference checks functionality:

• Policy elements must be entered in the correct order to resolve references. For example, if a prefix list is referenced in a policy statement, the prefix list must be entered first. This feature does not order policy statements so that references to policy elements exist.

• Variable expansion is not supported with the policy reference checks feature. Variables that reference policy elements that do not exist are not checked and are permitted.

• This feature is available only for configuring policies. If a policy is deleted, the command succeeds with no info or warning messages displayed. In the classic CLI, use the following command to display warnings for elements that do not exist.

  show router policy-edits

• The policy reference checks functionality is not supported with policy expressions.

Use the commands in the following context to configure route policies:

• MD-CLI

  configure policy-options policy-statement

• classic CLI

  configure router policy-options policy-statement

There are no default route policies. Each route policy must be explicitly created and applied. Applying route policies can introduce more efficiency as well as more complexity to the router capabilities.

A route policy impacts the flow of routing information or packets within and through the router. A routing policy can be specified to prevent particular customer routes from being placed in the route table, which causes those routes to not forward traffic to various destinations and the routes are not advertised by the routing protocol to neighbors.

Route policies can be created to control the following:

• export of all the active routes learned by a protocol

• route characteristics that determine which route is selected to act as the active route to reach a destination and advertise the route to neighbors

• import of all routes into the routing table, which must learn about particular routes to be able to forward packets and redistribute to other routing protocols

• damping

Before a route policy is applied, analyze the purpose of a policy and be aware of the results (and consequences) when packets match the specified criteria and the associated actions and default actions, if specified, are executed. Membership reports can be filtered based on a specific source address.

Each routing protocol has default behaviors for the import and export of routing information. The following table describes the default behavior for each routing protocol.

Routing policy statements can consist of as few as one or several entries. The entries specify the matching criteria. A route is compared to the first entry in the policy statement. If it matches, the specified entry action is taken, either accepted or rejected. If the action is to accept or reject the route, that action is taken and the evaluation of the route ends.

If the route does not match the first entry, the route is compared to the next entry (if more than one is configured) in the policy statement. If there is a match with the second entry, the specified action is taken. If the action is to accept or reject the route, that action is taken and the evaluation of the route ends, and so on.

Each route policy statement can have a default-action clause defined. If a default action is defined for one or more of the configured route policies, the default actions should be handled as follows:

• The process stops when the first complete match is found and executes the action defined in the entry.

• If the packet does not match any of the entries, the system executes the default action specified in the policy statement.

Route policy process example shows an example of the route policy process.

Use the following command option to configure the route policy to match a specific route policy entry and continue to search for other entries within the same route policy:

• MD-CLI

  configure policy-options policy-statement entry action action-type next-entry

• classic CLI

  configure router policy-options policy-statement entry action next-entry

Use the following command option to configure the route policy to match a specific route policy entry and continue to search for other entries within the next route policy:

• MD-CLI

  configure policy-options policy-statement entry action action-type next-policy

• classic CLI

  configure router policy-options policy-statement entry action next-policy

Policies can be constructed to support multiple states to the evaluation and setting of various route attributes.

Next policy logic example shows the next-policy and next-entry route processes.

For the default route policy actions, see Default route policy actions.

Damping initiates controls when routes flap. Route flapping can occur when an advertised route between nodes alternates (flaps) back and forth between two paths due to network problems that cause intermittent route failures. It is necessary to reduce the amount of routing state change updates propagated to limit processing requirements. When a route flaps beyond a configured value (the suppress value), then, that route is removed from the routing tables and routing protocols until the value falls below the reuse value.

A route can be suppressed according to the Figure of Merit (FoM) value. The FoM is a value that is added to a route each time it flaps. A new route begins with an FoM value of 0.

Damping is optional. If damping is configured, the following command values must be explicitly specified, as there are no default values:

• MD-CLI

  configure policy-options damping suppress
  configure policy-options damping half-life
  configure policy-options damping reuse
  configure policy-options damping max-suppress

• classic CLI

  configure router policy-options damping suppress
  configure router policy-options damping half-life
  configure router policy-options damping reuse
  configure router policy-options damping max-suppress

When the FoM value for a route exceeds the suppress value, the route is removed from the routing table. The route is considered to be stable when the FoM drops below the reuse value by means of the specified half-life parameter. The route is then returned to the routing tables. When routes have higher FoM and half-life values, they are suppressed for longer periods of time.

The following figure shows an example of a flapping route, the suppress threshold, the half-life decay (time), and reuse threshold. The peaks represent route flaps, the slopes represent half-life decay.

In the classic CLI, before creating a route policy or configuring route policy components, use the following command to enter edit mode.

configure router policy-options begin

The following error message displays when you try to modify policy options without entering begin first.

A:node-2>config>router>policy-options# policy-statement ‟allow all”
MINOR: CLI The policy-options must be in edit mode by calling begin before any changes can be made.

The following are other editing commands available in the classic CLI:

• commit

  This command saves changes made to route policies during a session.

• abort

  This command discards changes that have been made to route policies during a session.

There are no default policy statement command options. All command options must be explicitly configured.

Use the following command to create a route policy statement:

• MD-CLI

  configure policy-options policy-statement

• classic CLI

  configure router policy-options policy-statement

Use the following command to configure a text description for the route policy statement:

• MD-CLI

  configure policy-options policy-statement description

• classic CLI

  configure router policy-options policy-statement description

Specifying a default action is optional. The default action controls those packets not matching any policy statement entries. If no default action is specified for the policy, then the action associated with the protocol to which the routing policy was applied is performed. The default action is applied only to those routes that do not match any policy entries.

A policy statement must include at least one entry (see Configuring an entry).

Use the commands in the following context to configure a default action:

• MD-CLI

  configure policy-options policy-statement default-action

• classic CLI

  configure router policy-options policy-statement default-action

The following example displays a default-action configuration.

[ex:/configure policy-options]
A:admin@node-2# info
...
    policy-statement "1" {
        default-action {
            action-type accept
            damping "flaptest"
            next-hop 10.10.10.104
            as-path {
                add "test"
            }
            community {
                add ["365"]
            }
        }
    }

A:node-2>config>router>policy-options# info
----------------------------------------------
...
            policy-statement "1"
                default-action accept
                    as-path add "test"
                    community add "365"
                    damping "flaptest"
                    next-hop 10.10.10.104
                exit
            exit
----------------------------------------------

Use the following command to configure an entry for the route policy statement:

• MD-CLI

  configure policy-options policy-statement entry

• classic CLI

  configure router policy-options policy-statement entry

An entry action must be specified. Use the following command to specify an entry action:

• MD-CLI

  configure policy-options policy-statement entry action action-type

• classic CLI

  configure router policy-options policy-statement entry action

The other commands in the action context are optional.

The following example displays entry command option configurations and includes the default-action configuration that is shown in Configuring a default action.

[ex:/configure policy-options]
A:admin@node-2# info
...
    policy-statement "1" {
        entry 1 {
            to {
                neighbor {
                    ip-address 10.10.10.104
                }
            }
            action {
                action-type accept
            }
        }
        entry 2 {
            from {
                protocol {
                    name [ospf]
                    instance 1
                }
            }
            to {
                neighbor {
                    ip-address 10.10.0.91
                }
                protocol {
                    name [ospf]
                }
            }
            action {
                action-type accept
            }
        }
        default-action {
            action-type accept
            damping "flaptest"
            next-hop 10.10.10.104
            as-path {
                add "test"
            }
            community {
                add ["365"]
            }
        }
    }

A:node-2>config>router>policy-options# info
----------------------------------------------
...
            policy-statement "1"
                entry 1
                    to
                        neighbor 10.10.10.104
                    exit
                    action accept
                    exit
                exit
                entry 2
                    from
                        protocol ospf instance 1
                    exit
                    to
                        protocol ospf
                        neighbor 10.10.0.91
                    exit
                    action accept
                    exit
                exit
                default-action accept
                    as-path add "test"
                    community add "365"
                    damping "flaptest"
                    next-hop 10.10.10.104
                exit
            exit
----------------------------------------------

[ex:/configure policy-options]
A:admin@node-2# info
...
    policy-statement "1" {
        entry 1 {
            to {
                neighbor {
                    ip-address 10.10.10.104
                }
                protocol {
                    name [bgp]
                }
            }
            action {
                action-type accept
            }
        }
        entry 2 {
            from {
                protocol {
                    name [ospf]
                    instance 1
                }
            }
            to {
                neighbor {
                    ip-address 10.10.0.91
                }
                protocol {
                    name [ospf]
                }
            }
            action {
                action-type accept
            }
        }
        default-action {
            action-type accept
            damping "flaptest"
            next-hop 10.10.10.104
            as-path {
                add "test"
            }
            community {
                add ["365"]
            }
        }
    }

A:node-2>config>router>policy-options# info
----------------------------------------------
...
            policy-statement "1"
                entry 1
                    to
                        protocol bgp
                        neighbor 10.10.10.104
                    exit
                    action accept
                    exit
                exit
                entry 2
                    from
                        protocol ospf instance 1
                    exit
                    to
                        protocol ospf
                        neighbor 10.10.0.91
                    exit
                    action accept
                    exit
                exit
                default-action accept
                    as-path add "test"
                    community add "365"
                    damping "flaptest"
                    next-hop 10.10.10.104
                exit
            exit
----------------------------------------------

Community lists are composed of a group of destinations which share a common property. Community lists allow you to administer actions on a configured group instead of having to execute identical commands for each member.

Use the commands in the following context to configure community lists:

• MD-CLI

  configure policy-options community

• classic CLI

  configure router policy-options community

The following example displays a community list configuration.

[ex:/configure policy-options]
A:admin@node-2# info
    community "eastern" {
        member "100:200" { }
    }
    community "headquarters" {
        member "100:1000" { }
    }
    community "northern" {
        member "100:400" { }
    }
    community "southern" {
        member "100:500" { }
    }
    community "western" {
        member "100:300" { }
    }
    policy-statement "1" {
        entry 1 {
            to {
                neighbor {
                    ip-address 10.10.10.104
                }
                protocol {
                    name [bgp]
                }
            }
            action {
                action-type accept
            }
        }
    }

A:node-2>config>router>policy-options# info
----------------------------------------------
            community "eastern"
                members "100:200"
            exit
            community "western"
                members "100:300"
            exit
            community "northern"
                members "100:400"
            exit
            community "southern"
                members "100:500"
            exit
            community "headquarters"
                members "100:1000"
            exit
            policy-statement "1"
                entry 1
                    to
                        protocol bgp
                        neighbor 10.10.10.104
                    exit
                    action accept
                    exit
                exit
            exit
----------------------------------------------

The following considerations apply for damping:

• For each damping profile, all command options must be configured.

• The value of the suppress command must be greater than that of the reuse command (see Damping).

• Damping can be enabled at the global BGP level, BGP group level, and BGP neighbor level.

  Use the following command to enable damping at the global BGP level.

  configure router bgp damping

  Use the following command to enable damping at the BGP group level.

  configure router bgp group damping

  Use the following command to enable damping at the BGP neighbor level:

  • MD-CLI

    configure router bgp neighbor damping

  • classic CLI

    configure router bgp group neighbor damping

  Use the commands in the following context to configure a damping profile:

  Note: In the classic CLI, before configuring a damping profile, you must enter edit mode, as described in Beginning the policy statement in the classic CLI.

  • MD-CLI

    configure router bgp neighbor damping

  • classic CLI

    configure router policy-options damping

  If damping is enabled, but the route policy does not specify a damping profile, the default damping profile is used. This profile is always present and its command default values are configured as follows:

  • half-life – 15 minutes

  • max-suppress – 60 minutes

  • suppress – 3000

  • reuse – 750

The following example displays a damping configuration.

[ex:/configure policy-options]
A:admin@node-2# info
    damping "damptest123" {
        half-life 15
        max-suppress 60
        reuse 750
        suppress 1000
    }

A:node-2>config>router>policy-options# info
----------------------------------------------
            damping "damptest123"
                half-life 15
                max-suppress 60
                reuse 750
                suppress 1000
            exit
----------------------------------------------

Use the commands in the following context to configure prefix lists:

• MD-CLI

  configure policy-options prefix-list

• classic CLI

  configure router policy-options prefix-list

The following example displays a prefix list configuration.

[ex:/configure policy-options]
A:admin@node-2# info
    damping "damptest123" {
        half-life 15
        max-suppress 60
        reuse 750
    }
    prefix-list "western" {
        prefix 10.10.0.1/32 type exact {
        }
        prefix 10.10.0.2/32 type exact {
        }
        prefix 10.10.0.3/32 type exact {
        }
        prefix 10.10.0.4/32 type exact {
        }
    }

A:node-2>config>router>policy-options# info
----------------------------------------------
            prefix-list "western"
                prefix 10.10.0.1/32 exact
                prefix 10.10.0.2/32 exact
                prefix 10.10.0.3/32 exact
                prefix 10.10.0.4/32 exact
            exit
            damping "damptest123"
                half-life 15
                max-suppress 60
                reuse 750
            exit
----------------------------------------------