Avaya Aura Five Nines by PacketBase

Achieving Better than Five Nines
Availability with Avaya Aura ™

Bahareh Momken PhD, Avaya Labs
Robert McMaher MST, WW Technical Operations
Mark Kelsey, UC Product & Solutions Marketing

PacketBase, Inc.
www.packetbase.com

Agenda
 Introduction
 Advantages of Avaya Reliable Software
 Availability Measures and Solutions
 Midsize Enterprise Solution Case Studies
 Large Enterprise Solution Case Studies
 Methodology and Assumptions
– Notes on Availability Calculations (including Branch)
– LAN/WAN Design for High Availability
– Reliable Software Design Principles

For more information contact us at www.packetbase.com or 866.405.3992 - © 2010 Avaya Inc. All rights reserved. 2

Introduction

 Avaya offers a variety of communication software, servers,
gateways and availability features to meet the needs of
small, midsize and large enterprises
 Avaya can architect a “Five Nines” (99.999% availability)
or better solution for any customer at highly competitive
price points
 Some vendors have different perspectives as to what Five
Nines means and how it may be achieved
 This document aims to dispel some misconceptions in the
market and show how Avaya achieves Five Nines across
a range of customer scenarios


Advantages of Avaya Reliable Software

 Architected with a modular design and functional
independence to avoid complexity
 Built from existing designs with documentable quality
wherever possible
 Built-in system monitoring, failure detection, logging and
recovery mechanisms
 Software quality checks and reliability predictions at every
stage of development, system test and product
introduction
 Followed by periodic software availability assessments to
monitor and analyze data from the field

Availability Measures and Solutions

System Calculated Typical Solution Characteristics
Availability Downtime
per Year
99.999+% < 5 minutes Global geo-redundant, PSTN fall back, Processor
> Five Nines Ethernet duplication, redundant customer LAN/WAN,
clustered gateways (not remote) with Local Survivable
Processor (LSP) or Enterprise Survivable Server (ESS),
redundant servers and switches

99.999% 5 minutes Redundant customer LAN/WAN, remote clustered
Five Nines gateways with LSP or ESS, redundant servers
99.99% 53 minutes Reliable customer LAN, simplex WAN, single gateway
Four Nines with LSP or Standard Local Survivable (SLS), non-
redundant servers

99.9% 9 hours Non-reliable customer LAN/WAN susceptible to frequent
Three Nines failure and congestion


Achieving Better than Five Nines Availability with Avaya Aura™
Midsize Enterprise Solutions
(up to 450 endpoints)


Single Site Midsize Enterprise Solution

With Better than Five Nines Availability

Main Site > 5-9s availability
S8300 as Primary Server S8300 as LSP  Avaya Aura Communication
Manager (CM) on S8300 main
with S8300 LSP supported in
H.248 gateways with redundant
power supply
 S8300/S8300 Local Survivable
Processor (LSP) provides:
Redundant Customer LAN
– Alternate gatekeeper for phones
and gateways
– Connection preserving failover
(stable calls survive during
failover)
– Cluster of gateways providing
PSTN N+1 DSP resources and ISDN
T1/E1 trunks

Source: Avaya Labs


Multi Site Midsize Enterprise Solution with
Simplex Wide Area Network

S8300 as Primary Server S8300 as LSP


WAN/Internet Simplex
Remote Site ≥ 4-9s availability
PSTN
 Communication Manager on Standard Local
Survivable (SLS) or S8300 with LSP
 Simplex WAN link to branch is subject to failure
SLS or S8300 LSP
 Local stable calls survive during failover, calls
over WAN will fail
 When failover is complete, calls over WAN will
fall back over PSTN
PSTN


Redundant Wide Area Network



Remote Site = 5-9s availability
 Redundant WAN link improves site
availability
 LSP in branch + cluster of gateways
 Local stable calls survive during
failover, calls over WAN will fail (but
redundant WAN reduces failures)


Midsize Enterprise Case Study
S8300/S8300 LSP Availability Calculation - Main Site

S8300 primary server supported in H.248 gateway with redundant power 99.995%
S8300 as LSP supported in H.248 gateway with redundant power 99.995%
Redundant Customer LAN 99.9999%
Time to complete failover* < 3 minutes x 5% of Busy Hour traffic affected = 0.15 0.15 minutes
minutes average experienced downtime per failure

Availability from input of above data in Markov failure transition model = 99.9997%
Power/Environmental availability x 99.99955%

Availability for S8300/S8300 LSP Solution at Main Site = 99.9992%

*Failover is connection preserving, so stable calls survive

Note: Avaya Aura Communication Manager software reliability and availability data is based on analysis
of thousands of hours of field data ( 2,200+ system years per quarter)

Availability Assumptions (1 of 2)
 Gateway and IP phone failover to LSP is connection preserving (stable calls
survive during failover) for all calls. The 3 minutes of down time (which
includes failure detection, failover, gateway reset by LSP and phone re-
registration) is experienced by small percentage of users and depends on the
call rate.
 IP-phones TCP keep alive interval default value is 5 seconds with
administrable count with default being 5. Phones will discover that they have
lost the signaling channel within 25 to 45 seconds of the actual outage (the
default is 20 sec with 5 retransmissions at 5 sec intervals).
 The H.248 gateways send keep alive signals to Avaya Aura Communication
Manager (CM) every 15 seconds with a failure threshold of 3 times. CM sends
keep alive to the gateway every 20 seconds.
 Up to 30 alternate gatekeepers are available for the IP-phones and up to 4 for
the H.248 gateway.
 The cluster of H.248 gateways provide N+1 DSP resources and can
administer trunk groups in N+1 T1/E1 resources in order to provide service in
active/active mode (parallel).*
*Note: Gateways must be in connecting network regions in order to share DSP resources and ISDN trunks

 A single G450 Gateway with the option of redundant power supply (hot swap
FRU) has an availability value > 99.995%.
 Avaya Aura Communication Manager is supported on S8300 equipped with
Solid State Drive (SSD) and Hard Drive partitioning.
 450 IP phone re-registration to Processor Ethernet (PE) of S8300 < 1 minute.
 Gateway reset by new active server < 1 minute.
 Time to Service (TTS) phones and Short Network Outage: TTS enabled IP-
phones do not lose registration to the primary server and are back in service
immediately after the network heals.
 Standard Local Survivable (SLS) feature on H.248 gateways: with this feature
the gateway itself contains basic call control ability if the connection to the
main server is lost.
 Inter Gateway Alternate Routing (IGAR) provides an alternate means of
bearer connection between gateways when IP-WAN is incapable of carrying
the bearer traffic.
 PSTN fall back capabilities in the event of WAN outages.

Midsize Enterprise Solutions
(up to 2,400 endpoints)


Single Site Midsize Enterprise Solution

S8800 Primary Server S8800 as LSP  Avaya Aura Communication
Manager (CM) on S8800 main
with S8800 LSP & redundant
power supporting a cluster of
G450 Gateways
 S8800/S8800 LSP provides:
– Alternate gatekeeper for phones
and the gateways
– Connection preserving failover
(stable calls survive during
failover)
– Failure detection + complete
failover to LSP < 3 minutes
– Cluster of gateways providing
N+1 DSP resources and ISDN
T1/E1 trunks
PSTN

Source: Avaya Labs


Multi Site Midsize Enterprise Solution


 Communication Manager with
SLS, S8300 LSP or S8800 LSP
 Simplex WAN link to branch is
subject to failure
failover, calls over WAN will fail
 When failover is complete, calls
over WAN will fall back over
PSTN


Redundant Wide Area Network


 Redundant WAN link improves
site availability
 LSP in branch + cluster of
gateways
failover
 Calls over WAN will fail (but
redundant WAN reduces failures)


S8800/S8800 LSP Availability Calculation - Main Site

S8800 primary server with redundant power 99.996%
S8800 as LSP with redundant power 99.996%
Cluster of G450 Gateways > 99.9999%

Time to complete failover* < 3 minutes x 5% of Busy Hour traffic affected = 0.15 0.15 minutes

Availability from input of above data in Markov failure transition model 99.9998%

Availability for S8800/S8800 LSP Solution at Main Site = 99.9993%

*Failover is connection preserving, so stable calls survive
Note: Avaya Aura Communication Manager software reliability and availability data is based on analysis of thousands of
hours of field data (> 2,200+ system years per quarter) with S8730, S8510 and S8300 servers. S8800 performance is
expected to be equal or better.

 Gateway failover to LSP is connection preserving (stable calls survive during
failover) for all calls. The 3 minutes of down time (includes failure detection,
failover, gateway reset by LSP, phone re-registration) is only experienced by
small percentage of users and depends on the call rate.
 Avaya Aura Communication Manager supported on S8800 equipped with
RAID 1 Disk mirroring and optional redundant power supplies, has availability
prediction of 99.996%.
 2,400 IP phone re-registration to PE supported on S8800 ~ 1 minute.
 IP-phones TCP keep alive interval default value is 5 seconds with
administrable count. The default is 5. Phones will discover that they have
lost the signaling channel within 25 to 45 seconds of the actual outage.
 H.248 gateway sends keep alive signals to Communication Manager every 15
seconds with failure threshold of 3 times. Communication Manager sends
keep alive to the gateway every 20 seconds.
 Number of alternate gatekeepers for the IP-phones is up to 16 gate keepers
and up to 4 for H.248 gateways.



 Cluster of H.248 gateways provide N+1 DSP resources and N+1 T1/E1
resources providing service in active/active mode (parallel).*
 Single G450 Gateway with the option of redundant power supply (hot swap
FRU) has availability value > 99.995%.
 Gateway reset by new active server < 1 minute.
 TTS phones and Short Network Outage: TTS enabled IP-phone does not lose
registration to the primary server and is back in service immediately after the
network heals.
 Standard Local Survivable (SLS) feature on H.248 gateways: with this feature
the gateway itself contains basic call control ability if connection to the main
server is lost.
 PSTN fall back capabilities in the event of WAN outages.

*Note: Gateways must be in connecting network regions

Large Enterprise Solutions
(> 2,400 endpoints)


Single Site Large Enterprise Solution on
S8800 Server Pair with PE Duplication
(> 2,400 endpoints, H.248 Gateways)

 Avaya Aura Communication Manager on
S8800 Server Pair with Processor S8800 server with Processor Ethernet
Ethernet Duplication (PE) duplication
 End to end signaling and media
processor redundancy
– for IP phones and H.248 gateways
 Call Preserving server interchange
 IP phone registrations preserved
through server interchange
 Gateway registrations preserved
 Port Network calls survive through short
network outages
 Cluster of gateways providing N+1 DSP
resources and ISDN T1/E1 trunks

PSTN

Source: Avaya Labs


Multi Site Large Enterprise Solution on


 Communication Manager with SLS,
S8300 LSP or S8800 LSP
 Simplex WAN link to branch is subject
to failure
 When failover is complete, calls over
WAN will fall back over PSTN


Multi Site Large Enterprise Solution on


availability
failover
 Calls over WAN will fail (but redundant
WAN reduces failures)


Large Enterprise Case Study
Availability Calculation for S8800 Server Pair with Processor
Ethernet Duplication and H.248 Gateways - Main Site

S8800 Server Pair with Processor Ethernet Duplication > 99.9999%
Cluster of H.248 gateways providing N+1 DSP resources and ISDN T1/E1 trunks > 99.9999%

Server failover occurs in < 45 seconds and there is no service interruption = 0 0 minutes
minutes of downtime


Availability for Main Site > 99.9994%*

*Due to complexity and scale of Large Enterprise Solutions availability calculations may vary

Availability Assumptions for S8800 Server Pair with Processor
Ethernet Duplication & H.248 Gateways

 S8800 server pair has memory shadowing capability. This solution is
call preserving during server interchange (no interruption in service).
 TTS enabled IP-phones registration is retained during interchange.
 H.248 gateway registration retained during interchange.
 Fully redundant signaling paths for phones and gateways via
Processor Ethernet .
 Pool of N+1 DSP resources and trunk groups available on cluster of
G450 Gateways.
 G450 failover to LSP < 3 minutes.
 6,000 IP phone re-registration to Processor Ethernet (PE) < 2 minutes.


Single Site Large Enterprise Solution on S8800
with Mixed IP Connect & Processor Ethernet
(> 2,400 endpoints, G650/H.248 Gateways)

 Avaya Aura Communication
Manager on S8800 server pair
with mixed Processor Ethernet
(PE) duplication
 End-to-end signaling and
media processor redundancy
 G650 can provide redundant
IPSI, power supply, media
processing board and N+1
CLAN and trunks
 Clustering of H.248 gateways
N+1 DSP resources and ISDN
T1/E1 trunks
 Call Preserving server
interchange
 Gateway and IP phone
registrations preserved
 Port Network calls survive
through short network outages

Source: Avaya Labs

Multi Site Large Enterprise Solution on S8800


 Communication Manager with SLS,
S8300 LSP or S8800 LSP
 Simplex WAN link to branch is subject
to failure
 When failover is complete, calls over
WAN will fall back over PSTN


Multi Site Large Enterprise Solution on S8800



availability
failover
 Calls over WAN will fail (but redundant
WAN reduces failures)


Availability Calculation for S8800 Server Pair with Mixed IP
Connect and Processor Ethernet (G650/H.248) - Main Site

S8800 Server Pair with mixed IP Connect and Processor Ethernet > 99.9999%
Single G650 Gateway > 99.9995%
Cluster of H.248 gateways > 99.9999%

Server failover occurs in < 45 seconds and there is no service interruption = 0 0 minutes
minutes of downtime

Availability from input of above data in Markov failure transition model > 99.9998%

Availability for Main Site > 99.999%*


Availability Assumptions for S8800 Server Pair with Mixed IP Connect
and Processor Ethernet (G650 / H.248 Gateways)

 S8800 server pair has memory shadowing capability. This solution is call
preserving during server interchange (no interruption in service).
 TTS enabled IP-phones registration is retained during interchange.
 H.248 gateway registration retained during interchange.
 Fully redundant signaling paths via Processor Ethernet and IPSI boards.
 Fully redundant media path (320 Media Processor Board on G650).
 N+1 Trunk cards on G650.
 Pool of N+1 DSP resources and trunk groups available on cluster of G450
Gateways.
 S8800 ESS capacity is the same as the S8800 primary server pair.
 Stable calls on G650 will survive control network outages of up to 2 minutes.
 G650 and G450 Gateway failover to ESS in under 5 minutes.
 6,000 IP phones re-registration to Processor Ethernet (PE) < 2 minutes.


Acronyms

 CLAN: Control LAN interface  MTBF: Mean Time Between Failure
 DSP: Digital Signal Processor  MTTR: Mean Time to Repair
 ESS: Enterprise Survivable Server  PE: Processor Ethernet
 HW: Hardware  PN: Port Network
 ISDN: Integrated Services Digital  PS: Power Supply
Network
 SLS: Standard Local Survivable
 IGAR: Inter Gateway Alternate
Routing  SSD: Solid State Drive

 IPSI: IP System Interface  SW: Software

 LAN: Local Area Network  TTS: Time to Service

 LSP: Local Survivable Processor  UPS: Uninterruptible Power Supply

 MG: Media Gateway / Gateway  WAN: Wide Area Network


Achieving Five Nines Availability with Avaya Aura™
Methodology and Assumptions


Notes on Availability Calculations (1 of 4)
Why Markov Failure Transition Model
 Failure modes play a significant role in system reliability modeling and
requirements. System reliability modeling involves identifying a
system’s failure modes. Mathematical models are then developed to
predict the amount of time spent in those failure modes and the rate at
which the system fails.
 Markov Chain Reliability Modeling is used as the mathematical model
for predicting total system availability. The advantage of this
technique over others (for example, the parts count and combinatorial
models) is its ability in capturing the fault-tolerant aspect of the
platform. Avaya Aura products are designed to continue service in the
face of many failure events. Stable calls stay up in the event of loss of
connectivity to the primary server. IP-phones, Port Networks and
gateways do not lose registration in the event of short network
outages. Such resiliency is captured in the mathematical model in
assessing total system availability.

Branch Availability and its Dependence on Network Availability
 Customer Network Availability: high system availability makes the assumption that
customer network is designed with Best Practice Networking.
– Ref: http://support.avaya.com/elmodocs2/comm_mgr/r5.0/245600_6.pdf
 When the network connection is redundant, failure in one link is detected in few seconds
and traffic is re-routed in less than one minute of the failure. On the rare occasions
when the outage is not detected or lasts longer than 45 seconds remote gateways and
phones will search for an alternate gatekeeper and thus will be in service long before
the link failure heals.
 The frequency of such events is small and since failover to LSP is connection
preserving, a very small number of users (~ 5%) experience the service outage and total
downtime they experience per failure is no longer than 1-2 minutes.
 In a configuration that has a single WAN connection to the remote branch site, the
frequency of link failures will lead to higher number of failover to LSP or ESS. Such
events can occur as many as 2-3 events per month and each can last minutes or hours.
Avaya gateways and phones will detect loss of service from the primary server and will
search for service from the LSP within 45 seconds of the link loss.
 When the failover is complete (under 3 minutes), WAN calls will fall back to PSTN.
Since failover is connection preserving, only a small number of calls (5% in 3 minutes)
will be impacted.


Example 1:
 When the connection over the WAN is redundant:
– WAN Link connection Availability = 99.999%
– Expect 2-3 outage events per year which last longer than 45 seconds.
WAN MTBF = 4 to 6 months
– LSP failover is complete in less than 3 minutes (failure detection, MG reset, IP phone
registration.)
Branch MTTR = 3 minutes
– Outage in Branch is experienced by < 5% of the traffic*
What do we experience in Branch?
 Downtime/year
2-3 outages x 3 minutes x 5% =18 to 27 seconds
Average downtime experienced per end user as the result of WAN failure events
(1- (27 seconds)/(seconds in a year))=99.99991%
 Include server/LSP and power/environment availability
 Branch Availability over redundant WAN link:
99.9998% x 99.99955% x 99.99991% = 99.9993%

*Note that in fact in our testing labs the detection and failover completes in less than 2 minutes.

Example 2:
 When the connection over WAN is non-redundant:
– WAN link connection availability = 99% to 99.5%
– This type of connection experiences 2-4 outages per month and each can last hours
WAN MTBF = 1- 2 weeks, WAN MTTR = 0.5 – 4 hours
– LSP failover is complete in less than 3 minutes (failure detection, MG reset, IP phone
registration)
– In less than 3 minutes WAN calls will fall back to PSTN and it is business as usual.
Branch MTTR = 3 minutes
– Outage in Branch is experienced by < 5% of the traffic
What do we experience in Branch?
 Downtime/year
24 – 52 outages x 3 minutes x 5% = 3.6 – 7.8 minutes
Average downtime/year experienced per user due to WAN failures
(1-(8 minutes)/(minutes in a year)) = 99.998%
 Include server/LSP and power/environment availability
 Branch Availability over non-redundant WAN link:
99.995% x 99.99955% x 99.998% = 99.992%


Branch Availability Calculation (1 of 8)
G450 Gateway with Standard Local Survivable (SLS) and
Simplex WAN link to Remote Site

Communication Manager on primary server at Main Site 99.995%
H.248 gateway with Standard Local Survivable (SLS) at Branch 99.995%
Simplex WAN/Internet 99.5%
Time to complete failover < 3 minutes x 5% of Busy Hour traffic affected = 0.15 0.15 minutes


Availability for Remote Site > 99.99%


S8300 LSP with Simplex WAN link to Remote Site

S8300 primary server supported in H.248 gateway at Main Site 99.995%
S8300 Local Survivable Processor (LSP) supported in H.248 gateway at Branch 99.995%




S8300/S8300 LSP with Redundant WAN link to Remote Site

S8300 primary server supported in H.248 gateway at Main Site 99.995%
S8300 as LSP supported in H.248 gateway at Branch 99.995%
Redundant WAN/Internet 99.999%


Availability for Remote Site = 99.9993%


S8800 LSP with Simplex WAN link to Remote Site

S8800 primary server at Main Site 99.996%
S8800 Local Survivable Processor (LSP) at Branch 99.996%




S8800/S8800 LSP with Redundant WAN link to Remote Site

S8800 primary server with redundant power at Main Site 99.996%
S8800 as LSP with redundant power at Branch 99.996%
Cluster of G450 Gateways at Branch > 99.9999%





S8800 Server Pair/S8800 or S8300 LSP with Simplex WAN
link to Remote Site

S8800 primary server pair at Main Site > 99.9999%
S8800 or S8300 as LSP with redundant power at Branch 99.996%

Simplex WAN/Internet 99. 5%
H.248 gateway time to complete failover to LSP < 3 minutes x 5% of Busy Hour traffic 0.15 minutes
affected = 0.15 minutes average experienced downtime per failure




S8800 Server Pair/S8800 LSP with Redundant WAN link to
Remote Site

S8800 LSP with redundant power at Branch 99.996%

H.248 gateway time to complete failover to LSP < 3 minutes x 5% of Busy Hour traffic 0.15 minutes
affected = 0.15 minutes average experienced downtime per failure




S8800 Server Pair/S8800 LSP with Redundant WAN link to
Remote Site

S8800 ESS with redundant power at Branch 99.996%
G450 Gateways and G650 Gateway at Branch > 99.9999%

Time to complete failover to ESS < 5 minutes x 20 % of Busy Hour traffic affected = 1 1.0 minutes
minute average experienced downtime per failure




LAN/WAN Design for High Availability
 Because of the resource scarcity (high costs and lower bandwidths) in a WAN
environment, problems are more likely to manifest themselves in running IP
Telephony over a WAN versus on a LAN. Thus achieving better than 5 nines
is more challenging in the WAN environment than in the LAN.
What is a Reliable Customer LAN/WAN:
 Highly Reliable Networks can be achieved through the application of three
fundamental principles: Simplicity, Manageability and Scalability
– Simplicity: IT staff must interact with the network, so if the system is difficult to
understand the probability of error increases.
– Manageability: management capabilities and tools are required for implementation
of reliable change control procedures, to prevent improper network configurations
and to aid in detecting and reporting errors.
– Scalability: using designs that limit the impact of changes reduces the potential for
error. Excess bandwidth, unused ports and available addresses are required to
verify changes and to simplify network expansion. Modularity, design reuse, and
testability are all attributes of highly reliable networks.


Redundant (or Multipath) LAN/WAN (1 of 2)
 For the purpose of meeting high availability, the most commonly recommended network
topology consists of a redundant core with building blocks of layered routers and
switches.
 Multiple paths or link redundancy will minimize the disruption of service due to hardware
failure events, link congestions, denial of service attacks, etc. When a failure in one link
is detected, traffic will switch over to the healthy link. Link redundancy accommodates
the move of an endpoint or gateway from one switch to the other.
 It is important that the bandwidth of all links be equivalent and adequate to handle the
aggregated traffic.
 In Layer 2, Protocols such as Spanning Tree will allow loop free topology and Link
Aggregation Group (LAG) protocols will allow for quick discovery of failure and removal
of the failed link. This will reduce the convergence time to be nearly instantaneous.
 In Layer 3 switching, Routing Protocols will allow routers to dynamically learn the
topology of the network. Should the topology of the network change, routing protocols
update their internal topology table, which allows them to route around the failure.
– Protocols such as Virtual Router Redundancy (VRRP) provide a mechanism to
deal with router failure without disrupting endpoints or gateways.


Redundant (or Multipath) LAN / WAN (2 of 2)

 Example of a redundant topology:

OSPF manages
redundancy toward the
network core

Layer 3
(Distribution) Virtual Router Redundancy Protocol manages
Layer 3 redundancy toward the cluster

Layer 2 Rapid Spanning Tree
is used to manage Layer 2
(Access) redundancy

Note: Direct switch to
switch Layer 2 connection
required if Layer 3 devices do
not provide Layer 2 switching


Reliable Software Design Principles (1 of 4)
 Software failures are due to design flaws and logical errors made
during development.
– Avaya Aura Communication Manager software architecture is designed
with modular functionality and a fault resistant architecture
– Modules address specific sub-functions with cohesion and low coupling
– Built on Linux, which has fewer security flaws than other operating
systems and facilitates system customization to provide further security
 Software systems built from existing components typically have better
reliability and lower defect rates than systems built from scratch
– Years of applied dedication in software design have made
Communication Manager software a rock solid block
– Pervading all aspects of design is a continual architectural diligence
toward a consistent, logical system structure that allows an easy evolution
to the future
– Each release appropriately reuses proven foundations from the past


 System must be capable of monitoring itself to detect fault conditions,
when a failure occurs, the design itself must help alleviate the impact
of the failure
 Communication Manager (CM) maintenance architecture delivers
built-in intelligence and self healing abilities for systems at all levels
– CM software plays a central role in achieving high availability as
more than 30 percent of the lines of code are devoted to the
maintenance subsystem
– CM software is designed to automatically and continually assess
performance, detecting and correcting errors as they occur
– Software incorporates component & sub-assembly self-tests, error
detection/correction, system-recovery, and alarm escalation paths
– The maintenance subsystem manages hardware operation,
software processes and data relationships


 Reducing Mean Time to Restore Service (MTTR) depends on event
reporting, logging, and when possible automated remote maintenance
– The High Availability Platform (HAP) part of Communication
Manager software incorporates watchdog type monitoring of:
• health and sanity of the applications
• base operating system
• critical environmental conditions
– Degradation of service results in simultaneous recovery strategies
as well as alarming to services if necessary
– If such levels of software reboots fail, then the recovery escalates
to server hard reset
– All this is done without the need for dispatch to the site and hence
reduces MTTR to no more than few minutes


 Software quality check and assessing software reliability
– Avaya carefully examines every step of software
development by measuring faults during coding phase
– Software performance and reliability/recovery aspects
are tested in system verification lab, product
introduction and later in the field
– Bugs and Modification Request Metrics are included as
part of the data used in assessing software reliability
prediction*
– Avaya system availability analysis involves measuring
software field performance data of over 12,000
systems in the field
*Note: According to the methodology recommended by Telcordia GR-2813-CORE, Software Reliability Prediction

thank you

PacketBase, Inc.
www.packetbase.com
866.405.3992

Avaya Aura Five Nines by PacketBase

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