High Availability Technologies; Fault Detection Technologies - HP 6125G Configuration Manual

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 2 and level 3 high availability requirements by
decreasing MTTR.
High availability technologies can be classified as fault detection technologies or protection switchover
technologies.

Fault detection technologies

Fault detection technologies enable detection and diagnosis of network faults. CFD, DLDP, and Ethernet
OAM are data link layer fault detection technologies. BFD is a generic fault detection technology that
can be used at any layer. NQA is used for diagnosis and evaluation of network quality. Monitor Link and
Track work along with other high availability technologies to detect faults through a collaboration
mechanism.
Table 2 Fault detection technologies
Technology
CFD
DLDP
Ethernet OAM
BFD
NQA
Monitor Link
Introduction
Connectivity Fault Detection (CFD), which conforms to IEEE
802.1ag Connectivity Fault Management (CFM), is an end-to-end
per-VLAN link layer Operations, Administration and Maintenance
(OAM) mechanism used for link connectivity detection, fault
verification, and fault location.
The Device link detection protocol (DLDP) deals with unidirectional
links that may occur in a network. Upon detecting a unidirectional
link, DLDP, as configured, can shut down the related port
automatically or prompt users to take actions to avoid network
problems.
As a tool monitoring Layer 2 link status, Ethernet OAM is mainly
used to address common link-related issues on the "last mile". You
can monitor the status of the point-to-point link between two directly
connected devices by enabling Ethernet OAM on them.
Bidirectional forwarding detection (BFD) provides a single
mechanism to quickly detect and monitor the connectivity of links
or IP forwarding in networks. To improve network performance,
devices must quickly detect communication failures to restore
communication through backup paths as soon as possible.
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.
Monitor Link works together with Layer 2 topology protocols to
adapt the up/down state of a downlink port to the state of an uplink
port. This feature enables fast link switchover on a downstream
device in response to the uplink state change on its upstream
device.
2
Reference
"Configuring CFD" in
High Availability
Configuration Guide
"Configuring DLDP" in
High Availability
Configuration Guide
"Configuring Ethernet
OAM" in High
Availability
Configuration Guide
"Configuring BFD" in
High Availability
Configuration Guide
"Configuring NQA"
in Network
Management and
Monitoring
Configuration Guide
"Configuring Monitor
Link" in High
Availability
Configuration Guide