Vas Status And Vas Health Check - Cisco SCE 8000 10GBE Software Configuration Manual

VAS Status and VAS Health Check

VAS Status and VAS Health Check
To manage the VAS redundancy, the Cisco SCE platform needs to know the state of each VAS server.
The Cisco SCE platform performs periodic health checks for all the configured VAS servers. These
checks are the basis for VAS redundancy control; they enable the Cisco SCE platform to identify and
react to VAS server failure, and to check the connectivity between the Cisco SCE platform and the VAS
server before enabling the server to handle traffic.
The health check is performed over the VAS link, that is, the link that connects the Cisco SCE platform
with the VAS servers. It validates the traffic flow between the Cisco SCE platform and the VAS server
in both directions through special health check packets generated by the Cisco SCE platform.
The health check mechanism does not require special interaction with the VAS device. This is because
the VAS server does not have to answer health check packets; it only passes them as they are, back to
the Cisco SCE platform. As long as the packets are received by the Cisco SCE platform, the VAS server
is considered to be alive. Failing to receive the packets back from the VAS server within a predefined
time window is considered by the Cisco SCE platform as a failure of the VAS server and the server status
is changed to Down.
Health check packets are:
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•
The Cisco SCE platform uses default UDP ports beginning with 63140 and 63141 for VAS Server 0,
unless you configure different ports for the health check.
The Cisco SCE platform adds its own Layer 7 data on top of the UDP transport layer. This data is used
by the Cisco SCE platform to validate the correctness of the packet upon retrieval.
The health check is performed under the following conditions:
•
•
•
•
•
If the check is enabled, but any one of the conditions is not met, the server state will be Down (the same
as if the server did not pass the health check).
Check the connectivity between the Cisco SCE platform and the VAS server before you assign the server
to a server group.
Cisco SCE 8000 10GBE Software Configuration Guide
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Carried over UDP flows.
Contain source and destination IP addresses that can be user-configured.
IP addresses should be:
Unique to the Cisco SCE platform.
–
Addresses that are not used by the network traffic (such as private IPs).
–
VAS mode is enabled.
VAS server is enabled.
Health check for the VAS server is enabled.
Server has a VLAN tag.
Pseudo IPs are configured for the traffic interfaces.
Chapter 14 Value-Added Services (VAS) Traffic Forwarding
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