Cisco 10000 - Manual (Page 245)

8-5
Cisco 10000 Series Router Software Configuration Guide
OL-2226-23
Chapter 8 Configuring ATM Permanent Virtual Circuit Autoprovisioning
ATM PVC Autoprovisioning
When SAR the Page Limit is Reached
In releases earlier than Cisco IOS Release 12.3(7)XI2, if the SAR page limit was reached while you were
creating ATM PVCs, the router continued to create ATM PVCs but they were inactive.
In Cisco IOS Release 12.3(7)XI2, the router checks the SAR page limit before creating an ATM PVC.
If the SAR page limit has been reached, a message displays indicating that there are no more SAR pages
available for the PVC. A message similar to the following message is displayed for both individual ATM
PVCs and ATM PVCs that are configured within a range.
*Oct 28 21:09:26.535: SAR exhausted the number of pages available to create this VC
*Oct 28 21:09:26.535: %ATM-3-FAILCREATEVC: ATM failed to create VC(VCD=1173, VPI=147,
VCI=1408) on Interface ATM5/0/3, (Cause of the failure: VPI/VCI out of range.)
OC-12 ATM Line Card and VC Scaling
The SAR on the OC-12 ATM line card uses four priority levels, 0 through 3. Unspecified bit rate (UBR)
and virtual protocol (VP) tunnel use priority 3; variable bit rate (VBR) uses priority 2; and constant bit
rate (CBR) uses priority 0. Each priority level supports a maximum of 16,000 VCs.
Feature History for ATM PVC Autoprovisioning
Restrictions for ATM PVC Autoprovisioning
The ATM PVC autoprovisioning feature has the following restriction:
• The Segmentation and Reassembly (SAR) chip on the OC-3 and OC-12 ATM line cards is
responsible for all physical ports on the line card. Restrictions on how VCs are assigned might
reduce the VC counts.
• The ATM line cards use a pair of unidirectional SAR chips to segment and reassemble cells based
on priority levels. The architecture of the SAR limits the way in which you can assign VCs. In some
configurations, the limitation of the SAR can reduce the VC counts from the maximum number
typically support (for example, a maximum of 8000 VCs per port for the OC-3 and 16,000 per port
for the OC-12). For more information, see the
“ATM VC Scaling and VC Assignment” section on
page 8-4 .
• The SAR translates the external VPI/VCI values into an internal 32-bit logical header. Router
interfaces can support 510 unique bit field combinations in the 32-bit logical header. While there are
512 total SAR pages, page 0 is unused due to a hardware limitation and page 511 is reserved for
tunnels.
• On PRE3 and PRE4, to prevent LC SAR overflow, only 97 percent of the configured VC rate is used
internally.
Cisco IOS Release Description Required PRE
12.2(15)BX This feature was integrated into Cisco IOS Release
12.2(15)BX. PRE2
12.3(7)XI1 This feature was integrated into Cisco IOS Release
12.3(7)XI1. PRE2
12.2(28)SB This feature was integrated into Cisco IOS Release
12.2(28)SB. PRE2