Configuring Bfd - Cisco ME 3400 Software Configuration Manual

Configuring BFD

Table 35-13 ISO CLNS and IS-IS Clear and Show Commands (continued)
Command
show clns filter-set
show clns interface [interface-id]
show clns neighbor
show clns protocol
show clns route
show clns traffic
show ip route isis
show isis database
show isis routes
show isis spf-log
show isis topology
show route-map
trace clns destination
which-route {nsap-address | clns-name}
Configuring BFD
The Bidirectional Forwarding Detection (BFD) Protocol quickly detects forwarding-path failures for a
variety of media types, encapsulations, topologies, and routing protocols. It operates in a unicast,
point-to-point mode on top of any data protocol being forwarded between two systems to track IPv4
connectivity between directly connected neighbors. BFD packets are encapsulated in UDP packets with
a destination port number of 3784 or 3785.
In EIGRP, IS-IS, and OSPF deployments, the closest alternative to BFD is the use of modified
failure-detection mechanisms. Although reducing the EIGRP, IS-IS, and OSPF timers can result in a
failure-detection rate of 1 to 2 seconds, BFD can provide failure detection in less than 1 second. BFD
can be less CPU-intensive than the reduced timers and, because it is not tied to any particular routing
protocol, it can be used as a generic and consistent failure detection mechanism for multiple routing
protocols.
To create a BFD session, you must configure BFD on both systems (BFD peers). Enabling BFD at the
interface and routing protocol level on BFD peers creates a BFD session. BFD timers are negotiated and
the BFD peers send control packets to each other at the negotiated intervals. If the neighbor is not
directly connected, BFD neighbor registration is rejected.
Figure 35-6
neighbor (1), it sends a request to the BFD process to initiate a BFD neighbor session with the neighbor
OSPF router (2), establishing the BFD neighbor session (3).
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
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Purpose
Display filter sets.
Display the CLNS-specific or ES-IS information about each interface.
Display information about IS-IS neighbors.
List the protocol-specific information for each IS-IS or ISO IGRP routing
process in this router.
Display all the destinations to which this router knows how to route CLNS
packets.
Display information about the CLNS packets this router has seen.
Display the current state of the ISIS IP routing table.
Display the IS-IS link-state database.
Display the IS-IS Level 1 routing table.
Display a history of the shortest path first (SPF) calculations for IS-IS.
Display a list of all connected routers in all areas.
Display all route maps configured or only the one specified.
Discover the paths taken to a specified destination by packets in the network.
Display the routing table in which the specified CLNS destination is found.
shows a simple network with two routers running OSPF and BFD. When OSPF discovers a
Chapter 35 Configuring IP Unicast Routing
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