IP SLAs Configuration Guide, Cisco IOS XE Gibraltar 16 (Cisco ASR 900 Series)
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Loss Measurement
Management (LMM) is a loss monitoring feature implemented using the Smart SFP
on the Cisco ASR 900 Router . The LMM functionality is developed to monitor the
loss and delay traffic measurement data on the router.
Note
This is not applicable for Cisco ASR 900 RSP3 Module.
Prerequisites for
LMM
Smart SFP must
be installed on the port where Frame Loss Ratio and Availability (Loss
Measurements with LMM or LMR) is calculated.
Continuity check
messages (CCM)s must be enabled for LM and DM on the Smart SFP.
An untagged EFP
BD should be configured on the Smart SFP interface for LMM.
Note
Smart SFP must be installed on the router running with Cisco IOS XE
Release 3.12S and later post the ISSU upgrade. However, if the smart SFP must
be installed on a router running prior to Cisco IOS XE Release 3.12S, we
recommend that an IM OIR is performed post ISSU upgrade and an SSO performed
post ISSU upgrade.
Restrictions for Smart SFP
Smart SFP does not support Digital Optical Monitoring (DOM).
Maximum number of MEPS supported on the interfaces with Smart SFP is 64.
Maximum of 2 MEPs can be configured under EFP on a Smart SFP for LMM or Delay measurement management (DMM).
Off-loaded CC interval is not supported for EVC BD UP MEP.
Performance management (PM) sessions are generated with an interval of 1 second. The maximum number of sessions that are supported
are 1000.
LMM is not supported on the ten gigabit ethernet interface.
A single Smart SFP can act as an UP or down MEP only.
A MEP can participate in per cos LM or aggregate LM, but participating on both is not supported.
Y.1731 measurements are not supported on the Smart SFP which is connected to a port-channel.
The UP MEP, CFM and Y.1731 messages initiating or terminating at the MEP, are not accounted for in the LM statistics.
LMM is not support on below encapsulations:
Untagged
Priority-tagged
Default tagged
In the case of EVC BD UP MEP, all the interfaces on the BD participating in performance measurement should have Smart SFPs
installed, however the core facing interface associated with the MEP may have a standard SFP installed.
An untagged EVC BD must be configured on the interface installed with Smart SFP where MEP is configured for LM session.
Interoperability with platforms supporting long pipe QoS model requires explicit qos policy for cos to exp mapping and vice
versa.
Information About Loss Measurement Management (LMM)
Loss measurement management is achieved on the Cisco ASR 900 Series routers using the Smart SFP.
Y.1731 Performance Monitoring (PM)
Y.1731 Performance Monitoring (PM) provides a standard Ethernet PM function that includes measurement of Ethernet frame delay,
frame delay variation, frame loss, and frame throughput measurements specified by the ITU-T Y-1731 standard and interpreted
by the Metro Ethernet Forum (MEF) standards group. As per recommendations, devices should be able to send, receive and process
PM frames in intervals of 1000ms (1000 frames per second) with the maximum recommended transmission period being 1000ms (1000
frames per second) for any given service.
To measure Service Level Agreements (SLAs) parameters, such as frame delay or frame delay variation, a small number of synthetic
frames are transmitted along with the service to the end point of the maintenance region, where the Maintenance End Point
(MEP) responds to the synthetic frame. For a function such as connectivity fault management, the messages are sent less frequently,
while performance monitoring frames are sent more frequently.
ITU-T Y.1731 Performance
Monitoring in a Service Provider Network
ITU-T Y.1731
performance monitoring provides standard-based Ethernet performance monitoring
that encompasses the measurement of Ethernet frame delay, frame-delay
variation, and throughput as outlined in the ITU-T Y.1731 specification and
interpreted by the Metro Ethernet Forum (MEF). Service providers offer service
level agreements (SLAs) that describe the level of performance customers can
expect for services. This document describes the Ethernet performance
management aspect of SLAs.
Frame Delay and Frame-Delay
Variation
The Frame Delay
parameter can be used for on-demand OAM measurements of frame delay and
frame-delay variation. When a maintenance end point (MEP) is enabled to
generate frames with frame-delay measurement (ETH-DM) information, it
periodically sends frames with ETH-DM information to its peer MEP in the same
maintenance entity. Peer MEPs perform frame-delay and frame-delay variation
measurements through this periodic exchange during the diagnostic interval.
An MEP requires the
following specific configuration information to support ETH-DM:
MEG level—MEG
level at which the MEP exists
Priority
Drop eligibility—marked drop ineligible
Transmission rate
Total interval of
ETH-DM
MEF10 frame-delay variation algorithm
A MEP transmits
frames with ETH-DM information using the TxTimeStampf information element.
TxTimeStampf is the time stamp for when the ETH-DM frame was sent. A receiving
MEP can compare the TxTimeStampf value with the RxTimef value, which is the
time the ETH-DM frame was received, and calculate one-way delay using the
formula
frame delay =
RxTimef – TxTimeStampf.
One-way frame-delay
measurement (1DM) requires that clocks at both the transmitting MEP and the
receiving MEPs are synchronized. Measuring frame-delay variation does not
require clock synchronization and the variation can be measured using 1DM or a
frame-delay measurement message (DMM) and a frame-delay measurement reply (DMR)
frame combination.
If it is not
practical to have clocks synchronized, only two-way frame-delay measurements
can be made. In this case, the MEP transmits a frame containing ETH-DM request
information and the TxTimeStampf element, and the receiving MEP responds with a
frame containing ETH-DM reply information and the TxTimeStampf value copied
from the ETH-DM request information.
Two-way frame delay is calculated as (RxTimeb–TxTimeStampf)–(TxTimeStampb–RxTimeStampf), where RxTimeb is the time that the frame with ETH-DM reply information was received. Two-way frame delay and variation can
be measured using only DMM and DMR frames.
To allow more precise
two-way frame-delay measurement, the MEP replying to a frame with ETH-DM
request information can also include two additional time stamps in the ETH-DM
reply information:
RxTimeStampf—Time
stamp of the time at which the frame with ETH-DM request information was
received.
TxTimeStampb—Time
stamp of the time at which the transmitting frame with ETH-DM reply information
was sent.
The timestamping happens at the hardware level for DMM operations.
Note
The frame-loss, frame-delay, and frame-delay variation measurement processes are aborted when faults related to continuity
and availability occur or when known network topology changes occur.
An MIP is transparent
to the frames with ETH-DM information; therefore, an MIP does not require
information to support the ETH-DM function.
The figure below
shows a functional overview of a typical network in which Y.1731 performance
monitoring is used.
Figure 1. Y.1731
Performance Monitoring
Overview of Smart
SFP
The smart
SFP is a optical transceiver module that provides solutions for monitoring and
troubleshooting Ethernet services using standardized protocols. It supports CFM
and Y.1731 protocols as standalone device.
The Smart SFP
maintains per vlan per cos statistics for all MEP configured on the Cisco ASR
900 series routers. When the Smart SFP receives a loss measurement (LM) frame
matching a particular MEP, the statistics associated with particular MEP are
inserted on the LM frame. To support performance management (PM), the ASR 900
series router uses the Smart SFP to maintain per vlan per cos frame statistics
and to add statistics and timestamps for PM frames when the local router is
used as the source or the destination.
OAM
functions described in ITU-T Y.1731 allow measurement of following performance
parameters:
Frame Delay and
Frame Delay variation
Frame Loss Ratio
and Availability
Ethernet
frame delay and frame delay variation are measured by sending periodic frames
with ETH-DM (Timestamps) information to the peer MEP and receiving frames with
ETH-DM reply information from the peer MEP. During the interval, the local MEP
measures the frame delay and frame delay variation.
ETH-LM
transmits frames with ETH-LM (frame counts) information to a peer MEP and
similarly receives frames with ETH-LM reply information from the peer MEP. The
local MEP performs frame loss measurements which contribute to unavailable
time. A near-end frame loss refers to frame loss associated with ingress data
frames. Far-end frame loss refers to frame loss associated with egress data
frames.
To embed
ETH-LM information on a LM frame, the platform should be capable of maintaining
per vlan per cos statistics and insert this statistics into LM frames based on
the vlan and cos present on the LM frame. This is performed by the Smart SFP on
the Cisco ASR900 Series Routers.
Connectivity
The first step to performance monitoring is verifying the connectivity. Continuity Check Messages (CCM) are best suited for
connectivity verification, but is optimized for fault recovery operation. It is usually not accepted as a component of an
SLA due to the timescale difference between SLA and Fault recovery. Hence, Connectivity Fault Management (CFM) and Continuity
Check Database (CCDB) are used to verify connectivity. For more information on CFM, see Configuring Ethernet Connectivity Fault Management in a Service Provider Network.
Loss Measurement
Management (LMM) is a loss monitoring feature implemented using the Smart SFP
on the Cisco ASR 900 Router . The LMM functionality is developed to monitor the
loss and delay traffic measurement data on the router.
Note
This is not applicable for Cisco ASR 900 RSP3 Module.
Configure the bridge domain ID. The range is from 1 to 4000.
You can use the
split-horizon keyword to configure the port as a
member of a split horizon group. The
group-id range is from 0 to 2.
Step 7
rewrite
ingress tag pop {1 |
2}
symmetric
Example:
Router (config-if-srv)# rewrite ingress tag pop 1 symmetric
(Optional) Specify that encapsulation modification to occur on
packets at ingress.
pop
1—Pop (remove) the outermost tag.
pop
2—Pop (remove) the two outermost tags.
symmetric—Configure
the packet to undergo the reverse of the ingress action at egress. If a tag is
popped at ingress, it is pushed (added) at egress. This keyword is required for
rewrite to function properly.
Binds the
Ethernet port interface to an attachment circuit to create a pseudowire. This
example uses virtual circuit (VC) 101 to uniquely identify the PW. Ensure that
the remote VLAN is configured with the same VC.
Note
When
creating IP routes for a pseudowire configuration, we recommend that you build
a route from the xconnect address (LDP router-id or loopback address) to the
next hop IP address, such as ip route 10.30.30.2 255.255.255.255 10.2.3.4.
Router (config-if-srv)# monitor loss counter priority 0-7
Configures
monitor loss on the router.
priorityvalue—Specifies the Cos value. the valid values
are 0 to 7.
Step 11
end
Example:
Device(config-if-srv)# end
Returns to
privileged EXEC mode.
Configuring a Sender MEP for
a Single-Ended Ethernet Frame Loss Ratio Operation
Note
To display
information about remote (target) MEPs on destination devices, use the
showethernetcfmmaintenance-pointsremote command.
Perform this task to
configure a sender MEP on the source device.
Before you begin
Class of
Service (CoS)-level monitoring must be enabled on MEPs associated to the
Ethernet frame loss operation by using the
monitorlosscounter command on the devices at both ends of the
operation. See the
Cisco IOS
Carrier Ethernet Command Reference for command information. See the
"Configuration Examples for IP SLAs Metro-Ethernet 3.0 (ITU-T Y.1731)
Operations" section for configuration information.
Note
Cisco IOS
Y.1731 implementation allows monitoring of frame loss for frames on an EVC
regardless of the CoS value (any CoS or Aggregate CoS cases). See the
"Configuration Examples for IP SLAs Metro-Ethernet 3.0 (ITU-T Y.1731)
Operations" section for configuration information.
Device(config-ip-sla)# ethernet y1731 loss LMM domain xxx vlan 12 mpid 34 CoS 4 source mpid 23
Begins
configuring a single-ended Ethernet frame loss ratio operation and enters IP
SLA Y.1731 loss configuration mode.
To configure
concurrent operations, use the
SLM keyword
with this command. Repeat the preceding two steps to configure each concurrent
operation to be added to a single IP SLA operation number. Concurrent
operations are supported for a given EVC, CoS, and remote-MEP combination, or
for multiple MEPs for a given multipoint EVC.
Note
The session with mac-address will not be inactivated when there
is CFM error.
(Optional)
Specifies number of consecutive measurements to be used to determine
availability or unavailability status.
Step 8
frameintervalmilliseconds
Example:
Device(config-sla-y1731-loss)# frame interval 100
(Optional)
Sets the gap between successive frames.
Step 9
historyintervalintervals-stored
Example:
Device(config-sla-y1731-loss)# history interval 2
(Optional)
Sets the number of statistics distributions kept during the lifetime of an IP
SLAs Ethernet operation.
Step 10
ownerowner-id
Example:
Device(config-sla-y1731-delay)# owner admin
(Optional)
Configures the owner of an IP SLAs operation.
Step 11
exit
Example:
Device(config-sla-y1731-delay)# exit
Exits to IP
SLA configuration mode.
Step 12
exit
Example:
Device(config-ip-sla)# exit
Exits to
global configuration mode.
Step 13
exit
Example:
Device(config)# exit
Exits to
privileged EXEC mode.
What to do next
When you are
finished configuring this MEP, see the "Scheduling IP SLAs Operations" section
to schedule the operation.
Configuration
Examples for LMM
The following
example shows a sample output of LMM:
!
interface GigabitEthernet0/1/4
no ip address
negotiation auto
service instance 3 ethernet e3
encapsulation dot1q 3
service-policy input set-qos
xconnect 20.20.20.20 3 encapsulation mpls
cfm mep domain SSFP-3 mpid 3
monitor loss counter
!
!
ip sla 3
ethernet y1731 loss LMM domain SSFP-3 evc e3 mpid 30 cos 1 source mpid 3
history interval 1
aggregate interval 120
ip sla schedule 3 life 140 start-time after 00:00:05
!
Verifying LMM
Use the show ethernet cfm ma {local | remote} command to display the loss on the MEP domain
Router# show ethernet cfm ma local
Local MEPs:
--------------------------------------------------------------------------------
MPID Domain Name Lvl MacAddress Type CC
Ofld Domain Id Dir Port Id
MA Name SrvcInst Source
EVC name
--------------------------------------------------------------------------------
3 SSFP-3 3 0000.5c50.36bf XCON Y
No SSFP-3 Up Gi0/1/4 N/A
s3 3 Static
e3
2 SSFP-2 2 0000.5c50.36bf XCON Y
No SSFP-2 Up Gi0/1/4 N/A
s2 2 Static
e2
Total Local MEPs: 2
Router# show ethernet cfm ma remote
--------------------------------------------------------------------------------
MPID Domain Name MacAddress IfSt PtSt
Lvl Domain ID Ingress
RDI MA Name Type Id SrvcInst
EVC Name Age
Local MEP Info
--------------------------------------------------------------------------------
20 SSFP-2 c471.fe02.9970 Up Up
2 SSFP-2 Gi0/1/4:(20.20.20.20, 2)
- s2 XCON N/A 2
e2 0s
MPID: 2 Domain: SSFP-2 MA: s2
30 SSFP-3 c471.fe02.9970 Up Up
3 SSFP-3 Gi0/1/4:(20.20.20.20, 3)
- s3 XCON N/A 3
e3 0s
MPID: 3 Domain: SSFP-3 MA: s3
Total Remote MEPs: 2
Use the show ip sla interval-stastistics command to view the statistics.
Router# show ip sla history 3 interval-statistics
Loss Statistics for Y1731 Operation 3
Type of operation: Y1731 Loss Measurement
Latest operation start time: 09:19:21.974 UTC Mon Jan 20 2014
Latest operation return code: OK
Distribution Statistics:
Interval 1
Start time: 09:19:21.974 UTC Mon Jan 20 2014
End time: 09:21:21.976 UTC Mon Jan 20 2014
Number of measurements initiated: 120
Number of measurements completed: 120
Flag: OK
Forward
Number of Observations 101
Available indicators: 101
Unavailable indicators: 0
Tx frame count: 1000000
Rx frame count: 1000000
Min/Avg/Max - (FLR % ): 0:7225/000.00%/0:7225
Cumulative - (FLR % ): 000.0000%
Timestamps forward:
Min - 09:21:08.703 UTC Mon Jan 20 2014
Max - 09:21:08.703 UTC Mon Jan 20 2014
Backward
Number of Observations 99
Available indicators: 99
Unavailable indicators: 0
Tx frame count: 1000000
Rx frame count: 1000000
Min/Avg/Max - (FLR % ): 0:1435/000.00%/0:1435
Cumulative - (FLR % ): 000.0000%
Timestamps backward:
Min - 09:21:08.703 UTC Mon Jan 20 2014
Max - 09:21:08.703 UTC Mon Jan 20 2014
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Feature Information for Loss Measurement Management (LMM) with Smart SFP
The following table provides release information about the feature or features described in this module. This table lists
only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise,
subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco
Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1. Feature Information for Cisco NTP
Feature Name
Releases
Feature Information
Loss Measurement Management (LMM) with Smart SFP
Cisco IOS XE Release 3.12S
In Cisco IOS XE Release 3.12S, support was added for the LMM using Smart SFP on Cisco ASR 900 Series Routers.
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