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When preferential next hop node fails, through BFD and MPLS OAM, the PE detects that the
outer tunnel connecting the PE to the preferential node is unavailable. The PE sets a
corresponding flag in the LSP tunnel status table to indicates the outer LSP is unavailable and
delivers the flag to the forwarding engine. When the forwarding engine selects a forwarding
entry, it checks the LSP tunnel status corresponding to this forwarding entry. If the LSP tunnel
is unavailable, the engine uses the route of an inferior priority carried in this forwarding entry
to forward packets.
1.3.2 OAM (Operation Administration & Maintenance)
The OAM technology can simplify the network operation and test the network performance at
any time, which helps you to cut the network operation cost. This section describes only the
MPLS OAM technology.
MPLS is a key bearer technology applied to the extendable next generation network (NGN),
supporting multiple services guaranteed by QoS. A unique network layer is introduced to MPLS
and this layer may lead to faults. Therefore, MPLS must be competent with OAM.
MPLS supports different Layer 2 and Layer 3 protocols, such as IP, FR, and Ethernet. MPLS
offers an OAM mechanism entirely independent from upper and lower layers, enabling the
following features on the MPLS user plane:
l
Detecting the TE LSP connectivity
l
Performing switchover when a link fails to provide services according to Service Level
Agreements (SLAs)
With the MPLS OAM mechanism, the router can detect, identify, and locate a fault of MPLS
layer effectively. Then, the fault is reported and processed. In addition, when a failure occurs,
the protection switching mechanism can be triggered.
1.3.3 VRRP
Virtual Router Redundancy Protocol (VRRP) groups multiple routers into one virtual router,
and sets the address of the default gateway as the IPv6 address of the virtual router.
Generally, all hosts of a LAN are configured with the same default route to the gateway, for
example, Router A in
. In this manner, the hosts can communicate with external
networks. When the gateway fails, the communication between hosts and external networks is
interrupted.
Figure 1-1
LAN default gateway
Ethernet
Gateway:10.0.0.1
IP Address:10.0.0.2/24
Gateway:10.0.0.1
IP Address:10.0.0.3/24
Gateway:10.0.0.1
IP Address:10.0.0.4/24
RouterA
10.0.0.1/24
Network
HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability
1 Reliability Overview
Issue 02 (2014-09-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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