Specifications

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Cisco IGX 8400 Series Provisioning Guide, Release 9.3.3 and Later Releases
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Chapter 8 Cisco IGX 8400 Series ATM Service
ATM Service—Functional Overview
• Available bit rate (ABR), used for connections that do not require a timing relationship between the
source and the destination. ABR provides best-effort service, but does not provide guaranteed
minimum cell loss rate or cell transmission delay. ABR is often used for LAN-WAN services, such
as router traffic.
• Unspecified bit rate (UBR), which allows any amount of data (up to a configured maximum) to be
sent across the connection, but does not provide any guaranteed minimums for cell loss rate or cell
transmission delay.
Service Class Templates
Note Service class templates (SCTs) are primarily used with virtual circuits (VCs) and must be used when
configuring the IGX to work with a VSI master in a Label Switch Controller (LSC).
SCTs provide a way to map a set of standard connection protocol parameters to different hardware
platforms. For example, SCTs for the BPX and the IGX are different, but the BPX and IGX can still
deliver equivalent CoS for full QoS.
On the IGX, the NPM stores a set of SCTs. When a UXM or UXM-E is initially configured, the
appropriate SCTs are downloaded to the card. Later, if you configure a new interface on the card, the
appropriate SCTs for that new interface will also be downloaded to the card.
Each SCT contains the following information:
• Parameters necessary to establish a connection, including entries such as UPC actions, various
bandwidth-related items, and per-VC thresholds (for VCs)
• Parameters necessary to configure associated CoS buffers (Qbins) to provide QoS support
Each SCT has an associated Qbin mapping table, which manages bandwidth by temporarily storing cells
and serving them to the interface based on bandwidth availability and CoS priority.
Note The default SCT, Template 1, is automatically assigned to a virtual interface (VI) when you configure
the interface.
There are nine SCTs available for assignment to a VSI. For more information on SCTs, see Figure 8-1.
Caution SCTs can be reassigned on an operational interface, triggering a resynchronization process between the
UXM or UXM-E and the controllers. However, for a Cisco MPLS VSI controller, reassignment of an
SCT on an operational interface will cause all connections on the card to be resynchronized with the
controller, and can affect service.