Cisco Cisco 1700 2600 3600 3700 Series VPN Module 白書
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High Availability
Central to the high-availability model of a Cisco Virtual Switching System are the concepts of NSF/SSO and RPR.
The intricacies of these protocols are beyond the scope of this paper; you can find more information on these
protocols in the Catalyst 6500 documentation materials as well as in the following white paper:
“Non-Stop Forwarding and Stateful Switchover on the Catalyst 6500”
The high-availability model of the system changes when you integrate two chassis together into a single network
entity. In order to take advantage of the existing innovations in NSF/SSO technologies, Cisco Virtual Switching
System has implemented a high-availability model that uses this redundancy framework for an inter-chassis
environment (Figure 19).
Figure 13. Interchassis NSF/SSO in a Cisco Virtual Switching System Environment
In an SSO system, “high availability-aware” protocols and features may synchronize events and state information
from the active supervisor engine to the hot-standby supervisor engine. From a redundancy framework viewpoint,
the active supervisor engine acts as a server, whereas the standby supervisor engine acts as the client.
Information that is “high availability-aware” will be statefully synchronized between these entities. In the event of a
Information that is “high availability-aware” will be statefully synchronized between these entities. In the event of a
failover, the standby supervisor engine does not need to relearn this information, resulting in a minimal amount of
outage time.
As Figure 19 shows, the supervisor engine in the active virtual switch (Switch 1 in the figure) assumes the role as
the active supervisor engine, whereas the supervisor engine in the standby virtual switch (Switch 2) assumes the
role as the hot-standby supervisor engine. You can verify this situation with the following command:
VSS#sh switch virtual redundancy
My Switch Id = 1
Peer Switch Id = 2
Last switchover reason = none
Configured Redundancy Mode = sso
Operating Redundancy Mode = sso
Switch 1 Slot 1 Processor Information :
-----------------------------------------------
Current Software state = ACTIVE
Uptime in current state = 1 day, 19 hours, 30 minutes
Image Version = Cisco IOS Software, s72033_rp Software (s72033_rp-
ADVENTERPRISEK9_WAN_DBG-VM), Version 12.2(SIERRA_INTEG_070530) INTERIM SOFTWARE
ADVENTERPRISEK9_WAN_DBG-VM), Version 12.2(SIERRA_INTEG_070530) INTERIM SOFTWARE
Synced to V122_32_8_11, 12.2(32.8.11)SR on rainier, Weekly 12.2(32.8.11)SX85
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