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    Supporting External Parent Groups for Hierarchical Rate-Limiting on JunosE Routing Platforms

    The SRC software supports aggregate rate-limiting for JunosE dual-stack subscribers (IPv4 and IPv6). You can rate-limit traffic flow based on a common external rate-limit profile. This is accomplished by defining higher-level external parent groups and hierarchical policy parameters. An external parent group is a hierarchical rate-limit profile, which you define externally to a policy list so that it may be globally accessed by all classify-traffic conditions and internal parent groups within a policy list. Each external parent group can have an associated rate-limit profile and also have a reference to another external parent group.

    Note: The SRC software supports hierarchical rate-limiting for dual-stack (IPv4 and IPv6) PPP and static interfaces on E Series routers. The SRC software does not support external parent groups on E Series router L2TP interfaces, or on any other SRC software-supported routers.

    Consider the scenario shown in Figure 1, where two dual-stack PPP user sessions are configured over the same JunosE VLAN interface. Each PPP session corresponds to a dynamic user. Each PPP user can send combined IPv4 and IPv6 video traffic with a maximum rate of 1 Mbps. One of the subscribers, PPP user1, can send only a default maximum rate of 3 Mbps combined IPv4 and IPv6 session traffic, whereas the other subscriber, PPP user2, can send a default maximum rate of 5 Mbps combined IPv4 and IPv6 session traffic. The SRC software supports this scenario by pushing a hierarchical rate-limit profile to the E Series router.

    Figure 1: External Parent Groups Supporting JunosE Dual-Stack Subscribers

    External Parent Groups
Supporting JunosE Dual-Stack Subscribers

    The following references correspond to Figure 1:

    • EPG is the external parent group.
    • I1 and I3 are interfaces where IPv4 policies are attached.
    • I2 and I4 are interfaces where IPV6 policies are attached.
    • PPP1 is the PPP session of dynamic subscriber user1. I1 and I2 belong to this subscriber.
    • PPP2 is the PPP session of dynamic subscriber user2. I3 and I4 belong to this subscriber.
    • VLAN denotes the VLAN interface over which subscribers are configured.

    In the JunosE software, parent groups act as non-leaf nodes in a hierarchical policy. A hierarchy of policers can be built using classifier groups as leaf nodes and parent groups as parent nodes within a policy list. Each classifier group (with or without a rate limit) can point to a single parent group and that parent group can point to another parent group. The hierarchical policy parameter can be either a numeric aggregation where you can aggregate the JunosE classifier groups in terms of a number, or it can be a level-based aggregation where you can aggregate the classifier groups based on the JunosE interface type.

    The inter-interface hierarchical model includes references to parent groups that are defined externally from a policy list. These external parent groups enable the definition of hierarchical nodes outside the scope of a policy-list attachment. Each external parent group can have a rate-limit profile defined and have a reference to another external parent group.

    Classify-traffic conditions and parent groups within an SRC policy list can reference external parent groups for all policies that implement hierarchical policies. Each external parent group reference must also have a policy parameter name.

    You can reference external parent groups in policies in three ways:

    • From within a policy list that has its own rate-limit profile
    • From within a policy list that does not have its own rate-limit profile
    • From within a classify-traffic condition

    Figure 2 illustrates the external parent group policy structure.

    Figure 2: External Parent Group Policy Structure

    External Parent Group
Policy Structure

    External Parent Group Hierarchy

    You can define external parent groups in a hierarchical fashion. An external parent group can have multiple external parent groups as children, in which case there must be a hierarchical policy parameter defined for each child. The hierarchical policy parameter is applied to the external parent group when the child is referenced from a classify-traffic condition or an internal parent group in a policy list. Figure 3 depicts the creation of an external parent group EPG1 with two children: EPG2 and EPG3.

    Figure 3: Hierarchical External Parent Groups

    Hierarchical External
Parent Groups

    Hierarchy of Internal Parent Groups Referencing External Parent Groups

    You can refer to an external parent group from within an internal parent group. When you reference an external parent group from within an internal parent group, the SRC software passes the hierarchical policy parameter details to that external parent group from the internal parent group. To reference an external parent group, the internal parent group must specify the hierarchical policy parameter associated with the referenced external parent group. Figure 4 depicts the structure of an internal parent group ipg1 referencing an external parent group epg1 and having a child internal parent group ipg2.

    Figure 4: Internal Parent Group Referencing an External Parent Groups

    Internal Parent Group Referencing
an External Parent Groups

    Note: When referencing an external parent group from an internal parent group, the external parent group is referenced only at the first level of the internal parent group because the external parent group rate limit is applied only at the final stage.

    Hierarchy of Classify-Traffic Condition Referencing External Parent Groups

    Classify-traffic conditions can directly reference external parent groups in the same way they reference internal parent groups. To reference an external parent group, the classify-traffic condition must specify the external parent group name and the associated hierarchical policy parameter. Figure 5 illustrates an example of how you might reference an external parent group from a classify-traffic condition.

    Note: The parent group defined in the classify-traffic condition can refer to either an internal parent group or an external parent group, but not both.

    Figure 5: Referencing an External Parent Group from a Classify-Traffic Condition

    Referencing
an External Parent Group from a Classify-Traffic Condition

    Published: 2014-12-10