Huawei AR2200-S Series Configuration Manual page 147

Huawei AR2200-S Series Enterprise Routers
Configuration Guide - Reliability
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A dynamic BFD session triggered by a protocol is established using a dynamically allocated
local discriminator and a self-learned remote discriminator.
The following conditions must be met to allow two ends of a BFD session to create discriminators
using different methods:
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At present, a BFD session working as both a dynamic BFD session and a static BFD session
with automatically negotiated discriminators is supported by BFD for OSPF and BFD for
BGP.
Single-hop BFD and Multi-hop BFD
The AR2200-S supports single-hop BFD and multi-hop BFD to detect the reachability of IP
routes. This section describes single-hop BFD.
On the AR2200-S, common BFD sessions can be established on the following types of interfaces:
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On the AR2200-S, multicast BFD sessions can be established on the following interfaces:
Issue 01 (2012-01-06)
Dynamic BFD sessions triggered by a protocol
NOTE
l On the AR2200-S, OSPF, BGP, IS-IS, and PIM can dynamically trigger the establishment of BFD
sessions.
If a static BFD session is established on the local end using the manually specified
discriminators, the static BFD session must also be established on the remote end using the
manually specified discriminators.
If a static BFD session is established on the local end using the automatically negotiated
discriminators, the static BFD session can be established on the remote end using the
automatically negotiated discriminators or a dynamic BFD session can be established on
the remote end.
If a dynamic BFD session and a static BFD session with automatically negotiated
discriminators are configured on the local end, the following situations occur:
– If the dynamic BFD session and static BFD session share the same configurations (the
source address, destination address, outbound interface, and VPN index), the dynamic
BFD session coexists with the static BFD session.
– If the dynamic BFD session named DYN_local-discriminator is configured before the
static BFD session, the dynamic BFD session's name is replaced by the static BFD
session's name.
– Smallest values of the parameters of the two BFD sessions are used.
Physical interfaces: Layer 3 Ethernet interfaces, serial interfaces (including synchronous
SA interfaces, E1 interfaces, CE1/CT1/PRI interfaces, and CPOS interfaces), ATM
interfaces (including ADSL interfaces and G.SHDSL interfaces).
Logical interfaces: Ethernet sub-interfaces (including Dot1q sub-interfaces and QinQ sub-
interfaces), dialer interfaces, VLANIF interfaces, Layer 3 Eth-Trunk interfaces, virtual
Ethernet interfaces, virtual template interfaces, MP-Group interfaces, MFR interfaces,
serial sub-interfaces, channelized serial sub-interfaces, MFR sub-interfaces, ATM sub-
interfaces, and Eth-Trunk sub-interfaces (Dot1q sub-interfaces).
NOTE
When a physical Ethernet interface has multiple sub-interfaces, a BFD session can be established on
the physical Ethernet interface or each sub-interface.
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3 BFD Configuration
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