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ATM and Frame Relay SVCs, and SPVCs 8-5
Signaling Plane
Signaling Plane
To support ATM and Frame Relay SVCs, the BPX switches essentially overlay a signaling network
over a traditional (that is PVC-based) network. This signaling network, indicated by the dashed lines
in Figure 8-2, connects all of the BPX switches with ESP and extends to the CPE. The signaling
plane establishes and maintains SVCs between the CPE, that is, end users, across a Cisco StrataCom
wide-area ATM network.
Figure 8-2 BPX Switch with ESP Network Signaling Plane
The signaling plane is created out of two basic types of signaling channels:
• User to Network Interface (UNI) signaling channels.
• Network to Network Interface (NNI) signaling channels.
The signaling VCCs are normally configured during the provisioning of UNI ports and NNI trunks.
UNI Signaling Channel
There is an internal signaling VCC established between every UNI port on the BPX switch which
will support ATM or Frame Relay SVCs and the ESP in the BPX switch.There are two types of UNI
signaling channels supported by the BPX switch as shown in Figure 8-3.
• ATM UNI—For ATM CPE, these UNI VCCs extend from an ATM UNI port to the ESP. This is
either a one segment cross-connect between the BXM (or ASI) attached to the ATM CPE and the
BXM attached to the ESP within the BPX switch, or a two segment VCC from the MGX 8220
AUSM port connected to ATM CPE and the BXM attached to the ESP within the BPX switch.
(Note that VPI 0 and VCI 5 are reserved on the ATM UNI port for ATM SVC signaling channels.
The ILMI signaling channel will use VPI 0 and VCI 16, and the PNNI signaling channel will use
VPI 0 and VCI 18.)
• Frame Relay UNI—For Frame Relay CPE, there will always be a two segment VCC between the
MGX 8220 FRSM port connected to the ATM CPE and the BXM attached to the ESP within the
BPX switch. (Note that DLCI 0 is reserved on the Frame Relay UNI port for Frame Relay SVC
signaling channels.)
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S6358
WAN switching network