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Network Service Assurance

Embedded 'Always-On' Ethernet Devices for

Circuit 'Turn-Up' Testing & In-Service Assurance for Layer-

2 and Layer-3 Network infrastructures

www.metrodata.co.ukNetTESTER Embedded Network Service Testing Assurance

Ethernet (L-2) Network - Typical Scenario

Customer

Site ACustomer

Site B

Management

Access

Management

Access

Ethernet Service Providers typically offer End-to-End or Core-to-Edge services for their customers, which frequently

involve infrastructure, or at the least simple 'tail circuits', from one or more 3rd party Carriers. In order to verify that

actual network performance at all locations within the Customer network are as contracted from the Provider, cost-

effective test generators and/or traffic 'reflectors' can be embedded between the Provider's demarcation point and the

Customer's LAN Switch or Router hardware at each location, managed from the Customer's Network Operations

Centre (NOC).

Customer HQ

&

Network Operations

Centre (NOC)

Carrier's local

'Tail' Circuit

Carrier's local

'Tail' Circuit

Ethernet (Layer-2)

Infrastructure

Network


Ethernet (L-2) Service Verification Testing

Customer

Site ACustomer

Site B

1. Log in to Tester at Site A

3. Ethernet (L-2) Test traffic

generated at A is looped back

at B (SA/DA swapping, via

'SAM' hardware) for analysis

back at A

4. Results at A can be viewed from

NOC console or transmitted to the

NOC for inclusion directly to

service documentation

2. Set-Up RFC2544 or Y.1564 Test

in relation to SLA for service(s)

between sites A and B

In order to verify that the Service Provider(s) have provisioned circuits in accordance with the Customer's

requirements, Service Level Agreement (SLA) verification tests can be readily conducted between each location

Carrier's local

'Tail' CircuitCarrier's local

'Tail' Circuit

Customer HQ

&

Network Operations

Centre (NOC)

Ethernet (Layer-2)

Infrastructure

Network


Subsequent 'In-Service' Monitoring

Customer

Site A

Customer

Site B

Pro-active SNMP 'Trap'

alarm sent to NOC if

agreed SLA not met



agreed SLA not met

Y.1731 protocol exchanges time-

stamped test packets in order to

monitor service parameters relative to

pre-defined customer SLA

Subsequently, Customers may require to monitor that SLA performance metrics continue to be satisfied 'in-

service'. Pro-active alarming of potential 'SLA breach' conditions enable quick and effective remedial action.

Ethernet (Layer-2)

Infrastructure

Network

NOC

Carrier's local


'Tail' Circuit

Log-In to set up

Agreed Service Parameters

(SLA)

Log-In to set up


(SLA)


And with L-3 (IP) Network infrastructures?

Customer

Site ACustomer

Site B

If the Service Provider is provisioning a Layer-3 network, typically an IP-VPN, then to enable End-to-End performance

testing and monitoring, Layer-2 test functionality alone within the test points is insufficient. Ethernet MAC packets cannot

traverse Layer-3 elements of the network and Layer-3 (IP) packets are required. RFC2544 and/or Y.1564 testing is

agnostic to packet type, so IP-addressed frames can just as readily be used, provided that the embedded testers support

this, along with the necessary IP configuration tools and processes (e.g. ARP for IP Gateway address mapping).

Carrier's local


'Tail' Circuit

Customer HQ

&

Network Operations

Centre (NOC)

MPLS Layer-3, (IP)

Infrastructure

Network

Management

Access

Management

Access


And for in-service performance monitoring?

Customer

Site ACustomer

Site B

TWAMP protocol exchanges time-

stamped test packets in order to

monitor service parameters relative to

pre-defined customer SLA

TWAMP-lite

controllerTWAMP-lite

responder

For networks including Layer-3 (IP) elements, the 'Two-Way Active Measurement Protocol' (TWAMP) performs

a similar role to that of Y.1731 for 'Layer-2 only' networks, i.e. to monitor Latency and Jitter performance

characteristics, providing alarms in the event of breaches of the customer's SLA criteria.



agreed SLA not met



agreed SLA not met

NOC

Carrier's local


'Tail' Circuit

MPLS (Layer-3, IP)

Infrastructure

Network

Log-In to set up


(SLA)

Log-In to set up


(SLA)


Ethernet Network Performance Assurance

NT1002/3

Low cost test and/or reflection point (with line-rate Source/Destination Address swapping) for circuit set-up testing (RFC2544 and Y.1564). Also supports Y.1731 and TWAMP-lite for both Layer-2 (Ethernet MAC-addressed) & Layer-3 (IP addressed) services

NT1004/5

Advanced test and/or reflection point (with line-rate Source/Destination Address swapping) for circuit set-up testing (RFC2544 and Y.1564). Also supports Y.1731 and TWAMP-lite for both Layer-2 (Ethernet MAC-addressed) & Layer-3 (IP addressed) services. Dual-PSU resilient version available

Metrodata's NT1003 and NT1005 platforms include both Layer-2 and Layer-3 circuit testing and in-service monitoring regimes, offering deployment flexibility for each of Layer-2, Layer-3 & hybrid networks. If deployed permanently in-line, when not being used these embedded test devices simply pass all traffic transparently

NetTESTER


Example 1: Site-to-Site RFC2544 Test

Corporate HQ

Remote

Locn. 1

Network

Management

Console

NetTESTER NT1003

Remote log-in at NOC Console:

> Configuration

> Test initiation

> Progress monitoring

> Viewing of test reportsMPLS network

'Edge' Routers

Remote

Locn. 2

RFC2544 performance test can be initiated between

various sites throughout the network. Testing verifies

maximum bandwidth available and reports Latency, Jitter

and potentially Packet-loss Ratio for the link.

MPLS (Layer-3, IP)

Infrastructure

Network


Example 2: HQ-Branch Network link testing

MPLS (Layer-3, IP)

Infrastructure

Network

Corporate HQ

Branch Locn. 2

Branch Locn. 1

Branch Locn. 'N'

Network

Management

Console

NetTESTER NT1005

with dual-redundant PSU

NetTESTER NT1003

Remote log-in at NOC Console:

> Configuration

> Test initiation

> Progress monitoring

> Viewing of test reports

Y.1564 performance tests can be conducted

to any remote branch location,

independently of other links which may be

running live data. Testing verifies that

'Committed Information Rate' is being

achieved and reports Latency, Jitter and

potentially Packet-loss Ratio for the location,

whilst regular traffic to other sites is running

through the HQ link.

Single physical

'shared pipe'

network

connection

MPLS network

'Edge' Routers


Example 3: HQ-Branch Network monitoring

MPLS (Layer-3, IP)

Infrastructure

Network

Corporate HQ

Remote Office 2

Remote Office 1

Remote office 'N'

Network

Management

Console

NetTESTER NT1003

TWAMP 'background' monitoring can be used to generate alarms to

the Network Operations Centre in the event that (Latency, Jitter,

Packet-Loss) becomes out-of-specification and breaches pre-defined

'Service Level Agreements' for each link.

MPLS network

'Edge' Routers

NOC Console:

> Configuration of SLA thresholds

> Initiation of background monitoring

> SNMP 'Trap' alarm reception (SLA breach)

> Further investigation by individual unit log-in


Typical Network Management View


More NT100x family 'Testing' features

� The Layer-2 and Layer-3 testing so far described, can be conducted across Copper or Fibre WAN links from NetTESTER devices, since all products support copper or fibre (via SFP) connectivity at up to 1Gbps.

� The NetTESTER family also support additional features for 'Layer-1' testing of either copper or fibre links.

� As shown in the next slide, a simple 'TDR' test can be applied to the pairs within an RJ45 cable connected to the NetTESTER. If any of the pairs within the cable are 'open' (i.e. not connected, or broken') the distance to the fault is indicated.

� If the WAN port is connected via fibre, using specifically a Metrodata-supplied 'micro-OTDR' Optical Transceiver, then the NT100x will not only be able to indicate the length of the fibre connected, but also can be configured to issue a Network Management alarm should a fibre be disconnected whilst in-service. The alarm provides both a precise 'time-stamp' of the event and the distance to the discontinuity. This is illustrated in the following slides.


Simple Cat-5 Copper Cable Test screen

In this case, one of the pairs of the Cat 5E RJ45 cable is shown as being ‘cut’ at a distance of 10m from the tester.

This view is available at any of the LAN or WAN ports of the NetTESTER device


OTDR Fibre cable fault testing/alarming

This shows the SFP DDM data from an OTDR-capable Transceiver within the NetTESTER

In this case, the fibre has been 'patched' in and out' to several lengths as indicated...


Selecting Alarms for TRAP notification

Under configuration control, it is possible to select that an SNMP 'TRAP' alarm message is sent from the NT100x

in the event of a fibre breakage - the time and distance to the break is recorded within the alarm message

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Network Service Assurance

network service assurance - · pdf filethe network operations centre in the event that...

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