Lenovo Flex System Fabric CN4093, Application Manual

Page: 526 / 634

526
CN4093 Application Guide for N/OS 8.4
Failover Methods
With service availability becoming a major concern on the Internet, service
providers are increasingly deploying Internet traffic control devices, such as
application switches, in redundant configurations. Traditionally, these
configurations have been hot ‐ standby configurations, where one switch is active
and the other is in a standby mode. A non ‐ VRRP hot ‐ standby configuration is
shown in the figure below:
Figure 60.
A Non ‐ VRRP, Hot ‐ Standby Configuration
While hot ‐ standby configurations increase site availability by removing single
points ‐ of ‐ failure, service providers increasingly view them as an inefficient use of
network resources because one functional application switch sits by idly until a
failure calls it into action. Service providers now demand that vendors ʹ equipment
support redundant configurations where all devices can process traffic when they
are healthy, increasing site throughput and decreasing user response times when
no device has failed.
Enterprise NOS high availability configurations are based on VRRP. The
implementation of VRRP includes proprietary extensions.
The Enterprise NOS implementation of VRRP supports the following modes of
high availability:
 Active ‐ Active —based on proprietary Enterprise NOS extensions to VRRP
 Hot ‐ Standby —supports Network Adapter Teaming on your server blades
A
Internet
Servers
B
NFS Server
Primary Switch
IP: 200.200.200.100
Secondary Switch
IP: 200.200.200.101
Client Switches
Intranet Clients