7-6 - Implement Ethernet Operations, Administration, and Maintenance

Question 1

T/F: E-OAM is a protocol for installing, monitoring, and troubleshooting Metro Ethernet networks and Ethernet WANs. It is defined in IEEE 802.3ah specification.

Answer 1

True

Question 2

T/F: OAM frames, which are called OAM protocol data units (PDUs), use the slow protocol destination MAC address 0180.c200.0002. The MAC sublayer intercepts them, and they cannot propagate beyond a single hop within an Ethernet network.

Answer 2

True

Question 3

T/F: The frame transmission rate is limited to a maximum of 100 frames per second.

Answer 3

False. The frame transmission rate is limited to a maximum of 10 frames per second.

Question 4

Describe the OAM client.

Answer 4

-The OAM client establishes and manages E-OAM on a link.
-The OAM client also enables and configures the OAM sublayer.

Question 5

Describe the OAM sublayer.

Answer 5

The OAM sublayer presents two standard IEEE 802.3 MAC service interfaces:
one faces the superior sublayers, which include the MAC client (or link aggregation),
and the other interface faces the subordinate MAC control sublayer.
The OAM sublayer has three components:
control block
provides the interface between the OAM client and other blocks that are internal to the OAM sublayer.
It also includes the transmit process, which governs the transmission of OAM PDUs to the multiplexer, and a set of rules that govern the receipt of OAM PDUs from the p-parser.
multiplexer
manages frames that generate (or relay) from the MAC client, control block, and p-parser.
The multiplexer passes untouched through frames that the MAC client generates.
p-parser
classifies frames as OAM PDUs, MAC client frames, or loopback frames and then dispatches each class to the appropriate entity.
OAM PDUs transmit to the control block. MAC client frames pass to the superior sublayer. Loopback frames dispatch to the multiplexer.

Question 6

What two modules does the Cisco IOS Software implementation of E-OAM consist of?

Answer 6

The E-OAM shim is a thin layer that connects the E-OAM module and the platform code.
The E-OAM module, which is implemented within the control plane, handles the OAM client and control-block functionality of the OAM sublayer.
This module interacts with the CLI and Simple Network Management Protocol (SNMP) programmatic interface via control signals.

Question 7

T/F: The OAM features as defined by IEEE 802.3ah, Ethernet in the First Mile (EFM), are discovery, link monitoring, remote fault detection, remote loopback, and vendor-specific extensions.

Answer 7

True

Question 8

Describe E-OAM Discovery.

Answer 8

Discovery is the first phase of E-OAM, and it identifies the devices in the network and their OAM capabilities
During the discovery phase, the following information advertises within periodic information OAM PDUs:
OAM mode
OAM configuration (capabilities)
OAM PDU configuration
Platform identity

Question 9

Describe E-OAM Link Monitoring.

Answer 9

Link monitoring in E-OAM detects and indicates link faults under various conditions.
uses the event notification OAM PDU and sends events to the remote OAM entity when it detects problems on the link
The error events include the following:
Error symbol period (error symbols per second)
Error frame (error frames per second)
Error frame period (error frames per n frames)
Error frame seconds summary (error seconds per m seconds)
Because IEEE 802.3ah OAM provides no guaranteed delivery of any OAM PDU, the event notification OAM PDU may transmit multiple times to reduce the probability of a lost notification. A sequence number recognizes duplicate events.

Question 10

Describe E-OAM Remote Failure Indication.

Answer 10

The following failure conditions can disseminate:
Link fault
Dying gasp (vendor specific)
Critical event (vendor specific)

Question 11

Describe E-OAM Remote Loopback.

Answer 11

An OAM entity can put its remote peer into loopback mode by using the loopback control OAM PDU.
Loopback mode helps an administrator ensure the quality of links during installation or troubleshooting.
In loopback mode, every frame that is received transmits back on the same port except for OAM PDUs and pause frames.
The periodic exchange of OAM PDUs must continue during the loopback state to maintain the OAM session.

Question 12

Describe Vendor-Specific Extensions.

Answer 12

Ethernet OAM allows vendors to extend the protocol by creating their own type-length-value (TLV) fields.

Question 13

E-OAM supports four types of OAM messages:

Answer 13

Information OAM PDU
Event notification OAM PDU
Loopback control OAM PDU
Vendor-specific OAM PDU

Question 14

Benefits of 802.3ah high availability include the following:

Answer 14

Eliminates network downtime for Cisco software image upgrades, which results in higher availability.
Eliminates resource scheduling challenges that associate with planned outages and late-night maintenance windows.
Accelerates deployment of new services and applications and enables faster implementation of new features, hardware, and fixes by eliminating network downtime during upgrades.
Reduces operating costs due to outages while delivering higher service levels by eliminating network downtime during upgrades.

Question 15

Describe the configuration below.

Device> enable
Device# configure terminal
Device(config)# interface gigabitethernet 0/0/1
Device(config-if)# ethernet oam
Device(config-if)# exit

Answer 15

Set Up, Configure, and Verify E-OAM

Use the no ethernet oam command to disable the E-OAM feature on the interface.

Question 16

Describe the configuration below.

Device> enable
Device# configure terminal
Device(config)# interface gigabitethernet 0/0/1
Device(config-if)# ethernet oam
Device(config-if)# no ethernet oam link-monitor supported
Device(config-if)# exit

Answer 16

E-OAM Link-Monitoring Session

Use the following command to disable a link-monitoring session on the interface:
no ethernet oam link-monitor supported

Question 17

Describe the configuration below.

Device> enable
Device# configure terminal
Device(config)# interface gigabitethernet 0/0/1
Device(config-if)# ethernet oam
Device(config-if)# no ethernet oam link-monitor supported
Device(config-if)# exit

Answer 17

E-OAM Link-Monitoring Session

Use the following command to disable a link-monitoring session on the interface:
no ethernet oam link-monitor supported

Question 18

Describe the configuration below.

Device> enable
Device(config)# interface gigabitEthernet 0/0/2
Device(config-if)# ethernet oam
Device(config-if)# no ethernet oam link-monitor on
Device(config-if)# exit

Answer 18

E-OAM Link-Monitoring Operations

Use the following command to disable link monitoring operations on the interface:
no ethernet oam link-monitor on

Question 19

What does this command do?

Device# show ethernet oam summary

Answer 19

Verify an E-OAM Session

Question 20

What does this command do?

Device# show ethernet oam discovery interface gigabitethernet0/0/1

Answer 20

Verify E-OAM Discovery Status

Question 21

What does this command do?

Device# show ethernet oam statistics interface gigabitethernet0/0/1

Answer 21

Verify OAM PDU and Fault Statistics Information

Question 22

What does this command do?

Device# show ethernet oam status interface gigabitethernet0/0/1

Answer 22

Verify Link-Monitoring Configuration and Status

Question 23

What does this command do?

Device# show ethernet oam summary

Answer 23

Verify Status of Remote E-OAM Client

Question 24

Describe Ethernet CFM.

Answer 24

Ethernet CFM is an end-to-end per-service-instance Ethernet layer OAM protocol. End to end can be PE to PE or CE to CE.
Per service instance means per VLAN.
It is defined by IEEE 802.1ag specification.

Question 25

Ethernet CFM provides the following benefits:

Answer 25

End-to-end service-level OAM technology.
Reduced operating expense for service provider Ethernet networks.
Competitive advantage for service providers.
Supports both distribution and access network environments with the outward-facing maintenance endpoint (MEP) enhancement.

Question 26

Ethernet CFM Conceptual Information

Answer 26

Customer service instance: A customer service instance is an EVC that is identified by a service-provider VLAN (S-VLAN) within an Ethernet island and a globally unique service ID. A customer service instance can be point-to-point or multipoint-to-multipoint.
Maintenance domain: A maintenance domain is a management space for managing and administering a network. A single entity owns and operates a domain and defines the set of ports that are internal to it and at its boundary.
Ethernet CFM maintenance domain: A network administrator assigns a unique maintenance level in the range of 0 to 7 to each domain. Levels and domain names are useful for defining the hierarchical relationship that exists among domains. The hierarchical relationship of domains parallels the structure of customer, service provider, and operator. The larger the domain, the higher the level value.
Maintenance points: A maintenance point demarcates an interface that participates in a CFM. Maintenance points drop all lower-level frames and forward all higher-level frames. The two types of maintenance points include the following:
MEPs are points at the edge of the domain that define the boundary and confine CFM messages within the boundary. MEPs are inward-facing by default.
An inward-facing MEP sends and receives CFM frames through the relay function. It drops all CFM frames at its level or lower that come from the wire side.
An outward-facing MEP sends and receives CFM frames on the wire side. It drops all CFM frames at its level or lower that come from the relay function side.
Maintenance intermediate points (MIPs) are inside a domain, not at the boundary, and respond to CFM only when traceroute and loopback messages trigger them. They forward CFM frames that MEPs and other MIPs receive, drop all CFM frames at a lower level, and forward all CFM frames at a higher level, whether they are received from the relay or wire side.

Question 27

Ethernet CFM Messages

Answer 27

Continuity Check (Auto and On-demand):
In this fault detection mechanism, multicast heartbeat messages exchange periodically between MEPs that allow MEPs to discover other MEPs within a domain and allow MIPs to discover MEPs.
The continuity check can detect the following faults:
Unintended connectivity or service leaks
Unexpected sites
Loss of connectivity to a site
Link connectivity failure
Device failure (soft and hard)
Forwarding plane loops
CFM configuration errors
Loopback (ping):
In this fault-verification mechanism, a MEP transmits unicast frames at administrator request to verify connectivity to a particular maintenance point, which indicates whether a destination is reachable
The loopback mechanism contains the following capabilities:
Per EVC MAC ping (source to single destination).
Verify bidirectional connectivity between two CFM maintenance points (for varied frame sizes).
Traceroute:
This fault-isolation mechanism uses next-hop multicast from MEP to next MEP or MIP along the route. The receiver both replies with a unicast to the original MEP and sends the traceroute to the next MEP or MIP.
The link trace mechanism contains the following capabilities:
Engage per EVC MAC traceroute.
Discover MIPs on the path from source endpoint to destination endpoint.
Report ingress action, relay action, and egress action hop by hop.
Report encountered ACLs or STP-blocked ports.

Question 28

Which of the following is true about the E-OAM protocol?

A. OAM sublayer is responsible for establishing and managing E-OAM on a link.
B. OAM client presents two standard IEEE 802.3 MAC service interfaces.
C. Ethernet OAM module implementation is within the data plane.
D. OAM relies on a new, optional sublayer in the data link layer of the OSI model.

Answer 28

D