SIP Trunking Best Practices

EMEA Techshare 2009

The Future Begins

SIP Trunking – Best Practices

Aaron Miller

Systems Engineer – SP Specialist

April 1, 2009

EMEA Techshare 2009

The Future BeginsAgenda

What’s the big deal?

– What’s so great about SIP?

– Why are organizations moving to SIP trunking?

SIP trunk architecture

– Public and Private SIP trunks

– Review of TCP/TLS vs. UDP

– SES vs. SM – what’s the right choice for me?

Get it right the first time

– Aaron’s top ten best practices

– Closing thoughts

EMEA Techshare 2009












EMEA Techshare 2009

The Future BeginsWhat’s so great about SIP?

More than just telephony– SIP supports a wide range of services and enterprise

applications• Instant Messaging• Presence Management• Voice enabled, web-based e-commerce

The protocol itself is: –Extensible and Simple

•Text based, efficient messages – a lightweight protocol–Stable and Secure

•Been around since the late 90’s, enables encryption, authentication and additional security extensions

–Interoperable•SIP standards are being adopted by the telecommunications industry

EMEA Techshare 2009

The Future BeginsAvaya SIP Solution Architecture

CM

HomeSES

EdgeSES

(Core Router)

HomeSES

CM

MM

MX

MX

MM CM CM

SIP

CM: Communication ManagerSES: SIP Enablement ServicesMM: Modular MessagingMX: Meeting ExchangeAVP: Avaya Voice PortalG860: High Density Trunking GW

SIPCMBE

SIPCMBE

AVPG860

AuraSession Manager

EMEA Techshare 2009

The Future BeginsAre we in the future yet?

SIP trunking is following an adoption model similar to IP telephony

– Businesses on the cutting edge of technology have already adopted SIP trunking

– Many others are in the process of trialing it in pilot programs

– Interop testing is being worked at a frantic pace between enterprise vendors and service providers

The “Tipping Point” is now

– In the down economy, cost savings are critical for businesses

– Many greenfield installs are requesting a SIP trunking solution

EMEA Techshare 2009

The Future BeginsSIP trunking – what’s in it for me?

Enterprise benefits– Reduction on enterprise hardware

• Reduction in footprint, power consumption and maintenance charges

– Flexibility in provisioning / design / resource utilization– Architecturally ready for future applications– Potential cost savings– Enhanced survivability– Use of high fidelity codecs, e.g. G.722

Service Provider motivations to move to SIP trunking– Dwindling, and the expectation of dwindling, TDM revenues– Offer new services and applications to maintain profits– Incumbents need to keep smaller competitors (without TDM

capabilities) out of their accounts– Provide one access method for all voice and data services

EMEA Techshare 2009

The Future Begins Limitation & Challenges of Private IP (H.323) Trunking

IP WANIP WAN

PSTNLocal &

Long Distance

PSTNLocal &

Long Distance

IP Data &Telephony

• Private IP (H.323) trunks are limited to VoIP communications between internal systems/sites• Separate TDM interfaces are required for external communication (partners/suppliers/customers)• Extra cost, extra hardware, extra complexity

Customers/ Partners/ Suppliers

LAN LAN

TDM in

terfa

ces TDM

interfaces

Why SIP Trunking?Why SIP Trunking?

IP Phone IP Phone IP Phone IP Phone

Exter

nal C

omm

unicat

ions

External Comm

unications

Internal Communications

EMEA Techshare 2009

The Future Begins SIP Trunking A Single Pipe to the Cloud

WANWAN

PSTNLocal &

Long Distance

PSTNLocal &

Long Distance

H.323

SIPSIP

Customers/ Partners/ Suppliers

LAN LAN

IP Phone IP Phone IP Phone IP Phone

• Single IP link for voice/data• Optimize use of WAN access by consolidating voice and data services• Eliminate PSTN interfaces for long-distance and local access• Assign local telephone numbers to any ‘virtual location,’ independent of physical location• Save on toll charges• Prepares for future SIP solutions

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EMEA Techshare 2009

The Future BeginsFlavors of SIP Trunking

Service Provider Service Provider

Service Provider Enterprise / Contact Center(one or multiple locations)

Enterprise / Contact Center Enterprise / Contact Center

Enterprise / Contact Center Application Servers

SIP trunking can be over the LAN, WAN or dedicated circuits.

Routing to the IP address of the server is the key.

SIP trunking can be over the LAN, WAN or dedicated circuits.

Routing to the IP address of the server is the key.

EMEA Techshare 2009

The Future Begins A SIP Trunking Solution

SIP

Modular Messaging

Voice Portal

CM Branch EditionCommunication Manager

SESMeeting Exchange

Enterprise SBC

DS3/ISDN

G860

CustomersPartnersSuppliers

Avaya one-X©

Communicator

SIP SPPSTN

SIP

SIP

CustomersPartnersSuppliers

SP SBC

EMEA Techshare 2009

The Future BeginsBuilding Blocks of SIP Trunking

Service Provider

– Service

– Session Border Controller (SBC)

Customer Premise

– Edge security device: SBC, Firewall, etc

– Communication Platform: Server(s), Gateway(s),SIP Proxies, etc

– Application Servers: messaging, video & audio conferencing, collaboration tools, IM, Presence, and more

– Endpoints: hardphones, softphones, mobile devices, application integration

Service Provider

SBCServer / Gtwy

… or direct connection

EMEA Techshare 2009

The Future BeginsWhen do I need an SES?

An SES is required for two reasons

– SIP endpoints

– Private SIP trunking with adjuncts, i.e. MM, VP

What about TCP/TLS vs. UDP?– Most (read ALL) SP’s use UDP for their SIP trunking solutions– In the Enterprise, SIP trunking uses TCP or TLS– Therefore, something is required in the “middle” to do protocol translation

What’s the something?

– That’s up to you and the customer – it could be an SES, an SBC, or any real-time protocol converter

EMEA Techshare 2009

The Future BeginsAvaya SIP Trunking SolutionCM 4.0 Introduced Direct Connect

For a SIP trunking solution, either an SES or an SBC is required to do the TCP/TLS conversion to UDP

SIP SPSIP SP

CM

SBC

TCP (or TLS)

UDP

SES

This can be done by the SES

Or this can be done by the SBC

Or both can be used

We’ll discuss the differences between the SES and an SBC in subsequent slides

SES

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The Future Begins

SP SIP NWACME SBC SES

SIP Enablement Services with SM

Endpoints

VPAESMM

CM

SES

SM

GW

CM

GW

Endpointso o o o o o

Endpoints

MX

EMEA Techshare 2009

The Future BeginsKey Points

Sell SIP Enablement Services (SES) for:

– SIP Call Center

– DO System Integration

– Advanced SIP Telephony <1000 SIP Endpoints• Position SM Trial >1000 Endpoints

– Application Integration (Voice Portal, Modular Messaging)• Easy Upgrade to SM Later if Necessary

– Public SIP Trunking

SES SM Migration Path

– Database Conversion Tool Included with SM

– Customers Migrate from SES to SM at their own pace

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EMEA Techshare 2009

The Future BeginsLadies and Gentlemen…..

Aaron’s Top Ten Best Practices for Deploying SIP Trunking!!!

EMEA Techshare 2009

The Future Begins#10 – Ensure the SP offer has been tested in devConnect

SIP is described by many IETF RFCs, notably 3261– Each have many “SHOULDs”– Not all vendors implements all the “MUSTs”– Many SPs have equipment from various vendors

– Hence the SIP ‘standard’ is not tight Therefore it is absolutely critical that you ensure your SP

offer is certified through the Avaya devConnect program This is really not a “Best Practice” but rather a

requirement If you’re not sure –

– http://www.avaya.com/devconnect

EMEA Techshare 2009

The Future BeginsSIP SP devConnect members

EMEA– BT [Germany and Spain]

– Club Communications [UK]

– COLT [UK and Germany]

– KPN [Netherlands]

APAC– Singtel [Singapore]

– Telstra [Australia]

– TFN [Taiwan]

United States– AT&T

– BandTel

– Bandwidth.com

– Clear Channel Satellite

– ConneXon Telecom (911 Enable)

– Cox Communications

– Global Crossing

– Nectar (AGN Network)

– PAETEC (McLeodUSA)

– Telcordia

– Telepacific

– Verizon Business

– XO Communications

EMEA Techshare 2009

The Future Begins

DiscoveryDiscoveryPhasePhase

SupportSupportPhasePhase

CooperativeCooperativePhasePhase

CollaborationCollaborationPhasePhase

Collaborative TestingCollaborative Testing - Avaya and SP Labs are interconnected - SP allows Avaya engineers to lead test effort - Beta releases of Avaya code are consider for testing - Solution architectures are discussed as a team

Service Provider Independent Testing Limited ParticipationService Provider Independent Testing Limited Participation- The SP and Avaya start discussion regard “application” fit for Avaya CPE as edge technology to SP service offers. Usually customer/opportunity driven- Exploratory testing in SP’s lab with limited interactions with Avaya Test Engineering

- Sporadic often urgent demands for support when integration doesn’t work as expected- Unwilling to accept Avaya test results for integration certification- If Certification occurs, it follows the SP’s process in their Lab

SP Independent Testing onsite or remote SP Independent Testing onsite or remote ParticipationParticipation - Certification occurs in SP’s Lab with support from Avaya on-site or remotely - Relationships between Avaya and SP engineers start to develop - SP engineers take the lead role in conducting certification testing

Avaya & SP Cooperative Testing/CertificationsAvaya & SP Cooperative Testing/Certifications - Avaya Tests prior to going to SP lab - Avaya Lab test results are consider valid by SP however, certification still requires testing in SP’s Lab - Collaborative relationships are formed to solve integration issues

Getting to the Top with SP Certification

Background Background Evolution of Working Relationship with SPsEvolution of Working Relationship with SPs

Trust

& P

artn

ersh

ip

EMEA Techshare 2009

The Future Begins#9 – Use an SBC

A Session Border Controller on the Enterprise edge brings numerous advantages

Service Provider SBC is to provide protection and topology hiding of their network

Best practice: Enterprise customer should deploy their own SBC

Avaya recommends:– Acme Packet Net-Net SBC

Firewall that can handle real time packets

Network Address Translation / topology hiding

Call Admission Control

Protocol repair (remember those SHOULDs and MUSTs?)

CLAN load balancing

EMEA Techshare 2009

The Future BeginsSES and SBC Comparison

Capability Avaya SES Session Border Controller

Inbound Call Routing

Statically configured (Pattern Match) to specific CLAN. No Alternate Path or dynamic load Share*.

Load Balanced to Several CLANS, and intelligent add/removal of non-responsive CLANs from pool.

Local Server Redundancy Supported Supported

Geographic Redundancy Layer 2, same subnet Layer 2, same subnet

CM uses TCP or TLS and needs to be converted to UDP for SIP Service Provider

Supported Supported

Topology Hiding (of Customer's internal addressing, CLANs, Medpros, IP Endpoints.)

Not Supported

Customer SBC can terminate signaling and anchor media from Service Providers SBC. Customer SBC then speaks directly to CLANs, Medpros, IP Endpoints. This results in less exposure.

NAT Not Supported Supported

Call Admission Control

Integrated Firewall Enhanced Security Not Supprted Supported, higher layer/application level/DoS

Hardware Price Estimate dependent on resilience $5K - $20K ~$30K - 50K

SupportedNot Supported

EMEA Techshare 2009

The Future Begins#8 – Use CM 5.1.2 or greater

Very significant enhancements in CM 5.1.2 to public SIP trunking deployments

– This is also the load of software used in the latest devConnect and SIL testing

Fixes are not being backported to older loads

– Keep service packs up to date

Ensure the SES is also on the latest release

Sign up for email notifications to get the latest and greatest PSNs/PCNs for both CM and SES

– Check out http://support.avaya.com

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The Future Begins#7 – Be careful with Wi[l]d(5)cards*

“Wildcards” or regular expressions are used when configuring the SES to match host and media maps for both inbound and outbound trunks

{N} The preceding item is matched exactly N times.

. Matches any single character.

* Matches zero or more occurrences of the character immediately preceding. For example, the regular expression .* means match any number of any characters

– For example, ca*t will match "ct" (0 "a"characters), "cat" (1 "a"), "caaat" (3 "a"characters), and so forth

Online “Tutorial”: Regular Expressions explained

– http://www.regular-expressions.info/tutorial.html

EMEA Techshare 2009

The Future BeginsAddress Maps

• Our Goal: Route Extensions 45010 – 45019

• Our Lab Host Map: ^sip:4501[0-9]

^sip:777[0-9]{3}@example.com

• Matches sip:[email protected]

• Doesn’t match

• sip:[email protected]

• sip:[email protected]

Be aware that what may work for a current implementation may cause problems as additional media maps or hosts are added

^sip:77*@example.com

Matches sip:[email protected]

EMEA Techshare 2009

The Future Begins#6 – Be aware of CLAN load balancing, or lack thereof

The SES creates a direct one to one mapping between a SIP trunk and a CLAN

– No capability for the system to dynamically shift the trunk to another CLAN if there is a fault

– Potential issues with reliability and redundancy for critical deployments

This can be resolved by using an SBC, which does have the capability to dynamically balance the trunk amongst different CLANs

Or, use the Adjunct Route feature and administer the CLAN pools in a VDN

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The Future BeginsAdjunct System Routing Logic

SES Round-robin load-balances across the Adjunct Servers associated with the target Adjunct System

SESCombo /

Home

Adj. Server 1(e.g., MM MAS)

sip:[email protected]

Adj. Server 2sip:[email protected]


Adj. Sys.(e.g., MM)

x2000

1: Call 1

2: Call 2

3: Call 3

SESCombo /

Home

Adj. Server 1(e.g., MM MAS)

sip:[email protected]



Adj. Sys.(e.g., MM)

x2000

4: Call 4

5: Call 4

6: Call 4

If an Adjunct Server is non-responsive (failure/network outage, etc), fast-failover (~5 sec) to next Adjunct Server (if available)

EMEA Techshare 2009

The Future BeginsExample of SES load balancing using the « Adjunct Systems » feature

G650 with 2 CLANs

G650 with 1 CLANs

SIP / Acme Packet

SES Cluster withNetwork Duplication

CommunicationManagerMain andStandby

All calls to the VDN number,e.g.

0203285594

1

2

3

4

5

1

2

3

45 6

6

20000 BHCCOver 4 CLANS is a N+1 CLAN redundancy

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The Future Begins

#5 – Understand your duplication options

SES now offers cabled and network duplication

– Both offers are similar, work with a virtual IP address that front ends the system

– Network duplication offer requires both SES servers to be on the same subnet

Also possible to have two SES EDGE (or COMBO) servers in the same enterprise

– Duplication can be achieved through CM and the SP through the configuration of backup route patterns

– Please note that this can cause potential issues if SIP endpoints are brought into the environment

EMEA Techshare 2009

The Future Begins

Example config of non-duplicated SES

Service ProviderService Provider

G650G650Primary

Location 1

SES A Combo

G650 G650ESS

Location 2

SES B Combo

SBC

Primary Route Pattern

Secondary Route Pattern

EMEA Techshare 2009

The Future Begins

#4 - History info vs. Diversion Header

Service ProviderService Provider

x5555

Calling0207777555

5

SES02012345678

1) Inbound call from CPN 02012345678

2) Call routed over SIP trunk to CM IP phone, DDI 02077775555

3) Extension 5555 has EC500 set, CM sends outbound call onSIP trunk to mobile phone

4) CM sets History_info field to CPN of 02077775555

5) SP receives call from Avaya and checks the Diversion Header, whichAvaya doesn’t support

6) SP next checks P Asserted Identity; this is the number of the mobileextension we’re calling, also not recognized by the SP

7) Finally the SP checks the FROM field, but this is still set to the originalCPN of 02012345678. CM will never change this field.

8) SP is unable to route the call, and the call is rejected

EMEA Techshare 2009

The Future Begins

History info vs.Diversion Header CM 5.2 Major enhancement to SIP trunking capabilities with support

of Diversion Header Allows successful call redirect to a SIP Service Provider (SP) Implemented primarily for EC500 although the following is the full

set of supported features:– OPTIM applications EC500, ONE-X, CSP, FMC (PBFMC or

SPFMC)– Call Forwarding– Call Coverage– Call Vector Redirect

Uses the SIP Diversion Header– Partially implemented the expired IETF draft: draft-levy-sip-

diversion-08– SIP SPs tend not to support the standard History-Info header

and prefer to use the Diversion Header instead even though it is non-standard

– Support of the Diversion Header is widely deployed

EMEA Techshare 2009

The Future BeginsHistory info vs. Diversion Header

New SIP Trunk Group Protocol Variation field “Send Diversion Header? y/n” (default “n”)

The diverting user must be provisioned in public unknown numbering

New SIP Trunk Group Protocol Variation field “Support Request History? y/n” (default “y”)

– When the field is set to n(o) the History-Info header will not be transmitted (regardless of protocol signaling indicating the far end supports it) and CM will no longer signal support for it

– The Diversion Header and the History-Info header are mutually exclusive and can both be signaled

– At least one SP mandates that the History-Info header never enters their network under any condition

– Changing this default should be carefully considered and done only when absolutely necessary

EMEA Techshare 2009

The Future Begins#3 – Ensure timer on SIP Sig group is properly administered

Aaron Proxy Pizza

INVITE sip:[email protected]

INVITE sip:[email protected]

100 TRYING

180 RINGING

180 RINGING

Timer previously set to 2 seconds

Now administrableon SIP sig grp form

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The Future BeginsAlternate Route Timer Field

Added in CM 5.1 to provide an administrable value

Alternate Route Timer (sec) on the SIP Signaling Group form

•The range is 2- 30 seconds

•The default is 6 seconds

EMEA Techshare 2009

The Future Begins#2 – Consider a phased deployment

As with any new technology there may be challenges in the implementation

Depending on how the Authoritative SIP domains are setup, there may be a requirement to have dedicated inbound SIP trunks and dedicated outbound SIP trunks

Potential issues with dialplan portability may encourage the use of outbound trunks first

For initial roll-out ensure there are traditional TDM trunks for fall-back purposes

EMEA Techshare 2009

The Future Begins#1

Will I use an SBC or an SES?

Have we testedwith this SP?

What are the implications to the dial plan?

What is myduplication strategy?

Does this SP supportT.38 FAX?

What applications doesthe customer use now?

THINK!!!

What is the customer’s technology roadmap?

Is QoS enabled on the network?

How will I get feedback on bad calls?

Do I need separate trunks for inbound and outbound?

EMEA Techshare 2009

The Future BeginsClosing thoughts

SIP trunking is becoming more and more prevalent in enterprise deployments

Through continuous test efforts, the protocol is becoming more refined

With the release of Avaya Aura, knowledge of SIP trunking will become absolutely critical to everyone in this room

The future begins now – learn and understand how to design and deploy SIP trunking!

Documents

SIP Trunking Best Practices