R3204P16-HP Load Balancing Module High Availability Configuration Guide-6PW101

2
MTTR = fault detection time + hardware replacement time + system initialization time + link recovery time
+ routing time + forwarding recovery time. A smaller value of each item, a smaller MTTR and a higher
availability.
High availability technologies
Increasing MTBF or decreasing MTTR can enhance the availability of a network. The high availability
technologies described in this section meet the level 3 high availability requirements in the aspect of
decreasing MTTR.
High availability technologies can be classified into fault detection technologies and protection
switchover technologies.
Fault detection technologies
Fault detection technologies enable detection and diagnosis of network faults. NQA is used for
diagnosis and evaluation of network quality.
Table 2 Fault detection technologies
Technolo
gy
Introduction Reference
NQA
Network Quality Analyzer (NQA) analyzes network performance,
services and service quality through sending test packets, and
provides you with network performance and service quality
parameters such as jitter, TCP connection delay, FTP connection delay
and file transfer rate.
NQA
configuration in the
High Reliability
Configuration
Guide
Protection switchover technologies
Protection switchover technologies aim at recovering network faults. They back up hardware, link, routing,
and service information for switchover in case of network faults to ensure continuity of network services.
For more information about protection switchover technologies, see Table 3.
Table 3 Protection switchover technologies
Technolo
gy
Introduction Reference
Active and
Standby
Switchover
Devices supporting active and standby switchover are normally
equipped with two main boards, with one being the active main
board (AMB), and the other being the standby main board (SMB).
The configurations on the SMB are the same as those on the AMB.
When the AMB fails or is unplugged, the SMB automatically
becomes the AMB to ensure non-stop operating of the devices.
Active and standby
switchover
configuration in the
High Availability
Configuration Guide
VRRP
Virtual Router Redundancy Protocol (VRRP) is an error-tolerant
protocol, which provides highly reliable default links on multicast
and broadcast LANs such as Ethernet, avoiding network
interruption due to failure of a single link.
VRRP configuration in
the High Availability
Configuration Guide
A single availability technology cannot solve all problems. Therefore, a combination of availability
technologies, chosen on the basis of detailed analysis of network environments and user requirements,
should be used to enhance network availability. For example, access-layer devices should be connected
to distribution-layer devices over redundant links, and core-layer devices should be fully meshed. Also,
network availability should be considered during planning prior to building a network.