Atm Vc Scaling And Vc Assignment - Cisco 10000-2P2-2DC Software Configuration Manual

ATM PVC Autoprovisioning

ATM VC Scaling and VC Assignment

The ATM line cards support the full range of VPI//VCI pairs (unidirection only)—8 bit VPI range and
16 bit VCI range.
Cisco IOS Release 12.3(7)XI2 or later releases.
Table 8-1 Active VCs on ATM Line Cards
Line Card Max. VCs per Port
E3/DS3 4,096
OC-3 8,191
OC-12 16,384 (previously 14,436)
1. For 32,768 VCs per module, 4096 of them must be unshaped UBR VCs.
2. For 28,672 VBR, CBR, and shaped UBR VCs, no VCs can be in shaped VP tunnels. If VCs are in shaped VPs, the number of VBR, CBR, and shaped
UBR VCs is 22,204.
3. For 32,764 VCs per module, 4096 of them must be unshaped UBR VCs.
4. For 28,672 VBR, CBR, and shaped UBR VCs, no VCs can be in shaped VP tunnels. If VCs are in shaped VPs, the number of VBR, CBR, and shaped
UBR VCs is 22,204.
You can configure the maximum number of VCs across the ports in any fashion, provided that you do
not exceed the per-port maximum.
Although the maximum number of VBR, CBR, and shaped UBR VCs per E3/DS3 and OC-3 ATM line
card is 28,672 VCs, the router supports a maximum of 22,204 VBR, CBR, and shaped UBR VCs per line
card that you can place within virtual path (VP) tunnels. If you attempt to bring up more than 22,204
VCs in a configuration that includes VP tunnels and VCs (hierarchical traffic shaping configuration), the
VCs might not assign traffic correctly or the VCs might not come up at all. Be sure to limit the number
of configured VBR, CBR, and shaped UBR VCs on an ATM card to less than 22,204 VCs if you place
the VCs in VP tunnels.
For the OC-12 ATM line card, the router supports 16,384 VCs in VP tunnels.
A pair of unidirectional Segmentation and Reassembly (SAR) chips are used on the line cards, one for
the transmit direction and the other for the receive direction. The architecture of the SAR places limits
on the following values supported by the router's ATM interfaces:
•
•
•
To allow the SAR to support the same VPI/VCI values per interface and thus discriminate among the
VCs, the SAR translates the external VPI/VCI values into an internal 32-bit logical header that includes
bits for the port number. Router interfaces can support 510 (page 0 is unused due to a hardware
limitation; page 511 is reserved for tunnels) unique combinations of the following bit fields:
•
•
•
For more information, see the
ATM Router Interfaces
Cisco 10000 Series Router Software Configuration Guide
8-4
Table 8-1 lists the maximum number of active VCs supported on ATM line cards for
Maximum number of active VCs
Maximum number of VPI combinations that can be configured
Maximum number of VCI combinations that can be configured
PHY bits to designate the physical interface of the PVC. The OC-3 line card requires 2 bits for the
port number; the OC-12 line card doesn't require any bits; and the DS-2 line card requires 3 bits.
8 VPI bits (represents the entire VPI value)
Upper 9 bits of VCI value (bits 7-15 of the VCI field)
Understanding the Maximum Number of Active Virtual Circuits on Cisco
tech note.
Chapter 8 Configuring ATM Permanent Virtual Circuit Autoprovisioning
Maximum VCs per Module
1
32,768
3
32,764
16,384
No. VBR, CBR, Shaped UBR VCs
2
28,672
4
28,672
16,384
OL-2226-23