Beta Draft Confidential
2-161/19/05 ATM Services Configuration Guide for CBX 3500, CBX 500, GX 550, and B-STDX 9000
About ATM Logical Ports
ATMoMPLS UNI/NNI
Configuring VCC VPI Start and Stop Values for Virtual UNI/NNI
The CBX 3500, CBX 500, and GX 550 switches provide a virtual UNI/NNI feature.
The direct UNI/NNI provides the range of VCC VPI start and stop values. The range
of VPI start and stop values you define for the first virtual UNI/NNI must fall within
this range; it cannot overlap with the range you define for subsequent virtual UNI/NNI
ports.
For example:
The switch handles SVCs differently, depending on how you configure the
Connection Type field of the virtual UNI/NNI (see Table 3-4 on page 3-29). If the
logical port is set to the Network <-> Network Connection Type, it implies a network
scenario as shown in Figure 2-1 on page 2-11. In this case, the first VPI is used for
VCCs only. Additional VPIs can only be used for signaled VPCs with the best effort
QoS. If the logical port is set to the Network <=> Endsystem Connection Type, it
implies a network scenario as shown in Figure 2-2 on page 2-12. In this case, all
available VPIs can be used for either signaled VCCs or VPCs of any QoS class.
The restrictions described above only apply to SVCs. When using virtual UNI/NNIs
in conjunction with PVCs, there are no restrictions and the Connection Type field on
the logical port is not used.
ATMoMPLS UNI/NNI
The CBX 3500, CBX 500, and GX 550 ATMoMPLS UNI or NNI logical port types
enable you to configure an ATMoMPLS UNI or NNI logical port with a minimal
amount of bandwidth to act as the feeder port which enables interoperability between
Lucent and non-Lucent switches. This feeder logical port must be configured before
you can configure an ATMoMPLS trunk. For more information on ATMoMPLS UNI
and NNI LPorts, see Chapter 8, “Configuring ATM Over MPLS Trunks.”
About Logical Port Bandwidth
The maximum amount of logical port bandwidth does not equal the physical port
bandwidth due to the overhead associated with packaging ATM cells into the physical
layer frames. This overhead is different for each physical media type as well as the
different packaging methods. Table 2-5 provides a guide to mapping and converting
physical layer bandwidth to logical port bandwidth.
Logical Port VPI Start VPI Stop
First Virtual UNI/NNI 2 5
Second Virtual UNI/NNI 6 10
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