![Cisco ASR 9000 Serie Скачать руководство пользователя страница 219](http://html.mh-extra.com/html/cisco/asr-9000-serie/asr-9000-serie_configuration-manuals_66679219.webp)
Description
Operation
Tests the connectivity of a label switched paths (LSP)
and measures round-trip delay of the LSP in an MPLS
network. The following Forwarding Equivalence
Classes (FECs) are supported:
•
IPv4 Label Distribution Protocol (LDP)
•
Traffic engineering (TE) tunnels
•
Pseudowire
An echo request is sent along the same data path as
other packets belonging to the FEC. When the echo
request packet reaches the end of the path, it is sent
to to the control plane of the egress label switching
router (LSR). The LSR verifies that it is indeed an
egress for the FEC and sends an echo reply packet
that contains information about the FEC whose MPLS
path is being verified. Only a default VRF table is
supported.
MPLS LSP ping
Traces the hop-by-hop route of an LSP path and
measures the hop-by-hop round-trip delay for IPv4
LDP prefixes and TE tunnel FECs in an MPLS
network.
An echo request packet is sent data to the control
plane of each transit LSR, which checks if it is a
transit LSR for this path. Each transit LSR also returns
information related to the label bound to the FEC that
is being tested. Only a default VRF table is supported.
MPLS LSP trace
IP SLA Responder and IP SLA Control Protocol
The IP SLA Responder is a component embedded in the destination Cisco routing device that allows the
system to anticipate and respond to IP SLA request packets. The IP SLA Responder provides enhanced
accuracy for measurements. Additional statistics are also provided, which are not otherwise available through
standard ICMP-based measurements. The patented IP SLA Control Protocol is used by the IP SLA Responder,
providing a mechanism through which the responder is notified on which port it should listen and respond.
Only a Cisco IOS XR Software device or other Cisco platforms can be a source for a destination IP SLA
Responder.
Figure 4: IP SLA Operations, on page 201
shows where the IP SLA Responder fits relative to the IP network.
The IP SLA Responder listens on a specific port for control protocol messages sent by an IP SLA operation.
Upon receipt of the control message, the responder enables the UDP port specified in the control message for
the specified duration. During this time, the responder accepts the requests and responds to them. The responder
disables the port after it responds to the IP SLA packet or packets, or when the specified time expires. For
added security, MD5 authentication for control messages is available.
Cisco ASR 9000 Series Aggregation Services Router System Monitoring Configuration Guide, Release 4.2.x
203
Implementing IP Service Level Agreements
IP SLA Responder and IP SLA Control Protocol