Техническая Спецификация для Cisco 1-port ATM E3 port adapter PA-A6-E3=
Модели
PA-A6-E3=
Data Sheet
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Port Adapter advanced traffic management features mentioned previously are a direct result of this
SAR design.
The Cisco ATM Port Adapter also includes a large amount of buffer memory locally on the port
adapter, a feature unique to the Cisco ATM Port Adapter. This buffer memory is partitioned on a
per-virtual circuit and per-virtual path basis, providing better overall performance and the ability
to absorb large bursts of traffic. This design ensures that bursty traffic from one virtual circuit does
not prevent another virtual circuit from being serviced, an issue that could be crucial for any
service provider ATM network.
Advanced Bandwidth Management Feature
Advanced bandwidth management mechanisms in the ATM network module architecture allow for
the support of bursty client/server traffic while supporting applications that require guaranteed or
best-effort service. The Cisco ATM Port Adapter bandwidth management capabilities exceed those
of existing older ATM interfaces in midrange routers.
This new feature provides the ability to keep track of the bandwidth used by a virtual circuit or
virtual path on a per-interface basis. It prevents the oversubscription of the ATM link and is
configurable by the user.
The total bandwidth allocated on the interface is tracked by aggregating the values specified for
sustained cell rate for each virtual circuit. Whenever a new virtual circuit is requested, the
requested rate is checked against the available rate to ensure that the available bandwidth is not
exceeded. This check can be disabled if link-over subscription is desired.
ATM Layer Connection Management
OAM cells are used for ATM layer end-to-end link management messages. This ensures that the
remote end of the connection is alive and functioning. Support is provided for both OAM F4 and F5
flows. During segmentation, the OAM cells have the highest priority, and they are transmitted
ahead of other queued data. During reassembly, the OAM traffic is routed to a global OAM receive
buffer pool of 512 64-byte buffers.
MPLS
The MPLS feature classes that are supported include basic MPLS, MPLS traffic engineering,
MPLS VPN, and MPLS CoS.
IP to CoS Features
The Cisco ATM Port Adapter supports the Cisco IOS Software IP QoS-to-ATM CoS (IP-to-ATM
CoS) feature. This implements a solution for coarse-grained mapping of quality-of-service (QoS)
characteristics between IP and ATM. These features ensure consistent QoS between IP and
ATM interworked networks. IP/ATM networks can now offer different service classes across the
entire WAN, not just the routed portion. Critical applications can be given higher classes of service
during periods of high network usage and congestion. Great QoS flexibility becomes available for
more important traffic and user types.
Per-virtual circuit QoS features enable you to apply advanced queuing and bandwidth
management functionality such as Class-Based Weighted Fair Queuing (CBWFQ), Weighted
Random Early Detection (WRED), or low-latency queuing (LLQ) to an individual virtual circuit. Also