Table of Contents
Advertisement
Chapter 12
Value Added Services (VAS) Traffic Forwarding
Load Balancing and Subscribers
The system balances the usage of the VAS servers within a VAS Server Group, trying to create an equal
subscriber load for all the VAS servers in one VAS Server Group. The load balancing is subscriber based,
meaning that the subscribers are evenly distributed between the servers.
VAS load sharing is subscriber-based rather than bandwidth-based to ensure that all the traffic of the
subscriber gets to the same server so the server can make subscriber based decisions.
The SCE platform uses the same VAS server for all the traffic of a subscriber (per server group) even if
there is a change in the number of active servers in the group. Traffic from a subscriber is assigned to a
new server only if the current server becomes inactive. This will only apply on new flows. Flows that
were already mapped to a server before it became active will remain attached to it.
The mapping of subscriber to VAS servers not is saved across logouts or SCE platform reload
Load Balancing and Subscriber Mode
Since the load balancing is subscribers based, this solution will not work properly in subscriberless
mode, as the entire traffic load would be carried only by one VAS server per group.
Use anonymous mode rather than subscriberless mode with VAS traffic forwarding.
Note
In Pull mode, the first flow of the subscriber behaves as configured in the anonymous template. If no
anonymous template is configured, such first flows will be processed as defined by the default template.
Therefore, the default template should provide a proper package, so these flows will get VAS service.
VAS Redundancy
•
•
•
•
The services provided by the VAS servers should be highly available. The failure of a single VAS server
should not degrade the total system performance and availability. This requirement must be considered
when determining the number of VAS servers necessary for each VAS service.
There are two mechanisms by which the system guarantees the performance and availability of the VAS
services:
•
•
In addition to failure of an individual VAS server, a complete VAS Server Group is considered to be
failed if a defined minimum number of servers are not active.
OL-7827-12
VAS Server Failure, page 12-10
VAS Server Group Failure, page 12-10
Ethernet Switch Failure, page 12-10
Disabling a VAS Server, page 12-11
Load sharing — The SCE platform distributes the subscribers between all the active VAS servers
within a server group.
Monitoring — The SCE platform monitors connectivity with the VAS servers and handles server
failure according to the applied configuration.
Cisco SCE 2000 and SCE 1000 Software Configuration Guide
VAS Redundancy
12-9
Advertisement
Table of Contents
