Initialization procedure – Cisco 6500 User Manual
Page 26
4-26
Cisco IOS Software Configuration Guide, Release 12.2SX
OL-13013-06
Chapter 4 Configuring Virtual Switching Systems
Understanding Virtual Switching Systems
Each chassis in the VSS determines its system PFC mode. If the supervisor engine of a given chassis
is provisioned with PFC3CXL and all the switching modules in the chassis are provisioned with
DFC3CXL, the PFC mode for the chassis is PFC3CXL. However, if any of the switching modules
is provisioned with DFC3C, the chassis PFC mode will be set to PFC3C. If there is a mismatch
between the PFC modes of two chassis, the VSS will come up in RPR mode instead of SSO mode.
You can prevent this situation by using the platform hardware vsl pfc mode pfc3c command to
force the VSS to operate in PFC3C mode after the next reload.
•
SSO and NSF enabled
SSO and NSF must be configured and enabled on both chassis. For detailed information on
configuring and verifying SSO and NSF, see
Chapter 6, “Configuring NSF with SSO
Supervisor Engine Redundancy.”
If these conditions are not met, the VSS operates in RPR redundancy mode. For a description of SSO
and RPR, see the
“VSS Redundancy” section on page 4-11
Initialization Procedure
The following sections describe the VSS initialization procedure:
•
•
System Initialization, page 4-26
•
VSL Initialization
A VSS is formed when the two chassis and the VSL link between them become operational. Because
both chassis need to be assigned their role (VSS active or VSS standby) before completing initialization,
VSL is brought online before the rest of the system is initialized. The initialization sequence is as
follows:
1.
The VSS initializes all cards with VSL ports, and then initializes the VSL ports.
2.
The two chassis communicate over VSL to negotiate their roles (VSS active or VSS standby).
3.
The VSS active chassis completes the boot sequence, including the consistency check described in
the
“SSO Dependencies” section on page 4-25
.
4.
If the consistency check completed successfully, the VSS standby chassis comes up in SSO VSS
standby mode. If the consistency check failed, the VSS standby chassis comes up in RPR mode.
5.
The VSS active chassis synchronizes configuration and application data to the VSS standby chassis.
System Initialization
If you boot both chassis simultaneously, the VSL ports become VSS active, and the chassis will come
up as VSS active and VSS standby. If priority is configured, the higher priority switch becomes active.
If you boot up only one chassis, the VSL ports remain inactive, and the chassis comes up as VSS active.
When you subsequently boot up the other chassis, the VSL links become active, and the new chassis
comes up as VSS standby.