Specifications

17-34
System Management Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches
Chapter 17 Configuring Ethernet OAM, CFM, and E-LMI
Information About the Ethernet OAM Protocol
Hold-time: 100 Minutes
You can use the privileged EXEC commands in the following table to display IP SLAs Ethernet CFM
information:
Information About the Ethernet OAM Protocol
The Ethernet OAM protocol for installing, monitoring, and troubleshooting Metro Ethernet networks
and Ethernet WANs relies on an optional sublayer in the data link layer of the OSI model. Normal link
operation does not require Ethernet OAM. You can implement Ethernet OAM on any full-duplex
point-to-point or emulated point-to-point Ethernet link for a network or part of a network (specified
interfaces).
OAM frames, called OAM protocol data units (OAM PDUs) use the slow protocol destination MAC
address 0180.c200.0002. They are intercepted by the MAC sublayer and cannot propagate beyond a
single hop within an Ethernet network. Ethernet OAM is a relatively slow protocol, with a maximum
transmission rate of 10 frames per second, resulting in minor impact to normal operations. However,
when you enable link monitoring, because the CPU must poll error counters frequently, the number of
required CPU cycles is proportional to the number of interfaces that must be polled.
Ethernet OAM has two major components:
• The OAM client establishes and manages Ethernet OAM on a link and enables and configures the
OAM sublayer. During the OAM discovery phase, the OAM client monitors OAM PDUs received
from the remote peer and enables OAM functionality. After the discovery phase, it manages the rules
of response to OAM PDUs and the OAM remote loopback mode.
• The OAM sublayer presents two standard 802.3 MAC service interfaces facing the superior and
inferior MAC sublayers. It provides a dedicated interface for the OAM client to pass OAM control
information and PDUs to and from the client. It includes these components:
– The control block provides the interface between the OAM client and other OAM sublayer
internal blocks.
– The multiplexer manages frames from the MAC client, the control block, and the parser and
passes OAM PDUs from the control block and loopback frames from the parser to the
subordinate layer.
– The parser classifies frames as OAM PDUs, MAC client frames, or loopback frames and sends
them to the appropriate entity: OAM PDUs to the control block, MAC client frames to the
superior sublayer, and loopback frames to the multiplexer.
Command Purpose
show ip sla configuration
[entry-number]
Displays configuration values including all defaults for all IP
SLAs operations or a specific operation.
show ip sla ethernet-monitor
configuration [entry-number]
Displays the configuration of the IP SLAs automatic
Ethernet operation.
show ip sla statistics [entry-number |
aggregated | details]
Display current or aggregated operational status and
statistics.