IPSI 20Signaling 20Bandwidth 20Requirements 20V4

© 2005 Avaya Inc. All rights reserved.

IPSI Signaling Bandwidth Requirements for WAN IP Connected G650 Port Networks

IPSI Signaling Bandwidth Requirements for WAN IP Connected G650 Port Networks

Presented by Ken Wnuck

2© 2005 Avaya Inc. All rights reserved.

IPSI Signaling Bandwidth

What is IPSI Signaling?How we TestedBandwidth ProvisioningLayer 3 Traffic ClassificationCisco CBWFQ and LLQExtreme QoS ProfilesConclusionsPhase II Initiatives


IPSI CONTROL TRAFFIC

The IPSI circuit pack (TN2312AP/BP) provides enterprises with the capability to IP-connect Port Networks over LAN/WAN links in simplex and high availability configurations.The IPSI signaling traffic is encapsulated AVAYA proprietary CCMS (Control Channel Message Set) messages inside TCP/IP packets.CCMS Call Signaling and System Maintenance traffic is passed between S87XX/S8500 call control servers and the IPSI circuit packs in a port network. The CCMS messages are used for:

– H.323, H.225 RAS, and Q.931• Register IP endpoints via local

CLANs to the S8XXX server.• Setup and Teardown calls• Periodic testing of the hardware. • KeepAlives

The encapsulated CCMS messages are critical to the stability of a port network and delivery of CCMS messages must be guaranteed.


System Test Model


Methodology

CM 4.0150 TARTS IP endpoints registered per region, where each of the two PNs had its own isolated region.The originating TARTS IP endpoints were used to generate traffic over two ISDN PRI trunks that then terminated to a second set of 150 TARTS IP endpoints on the second PN. This provided our outbound and inbound simulated PSTN trunk traffic respectively

– no inter-port network VoIP traffic, all bearer traffic traversed via the ISDN PRI trunks– Poisson Distribution for random call patterns

Call durations were 10 secondsBHCC call rates were 1K, 2.5K, 5K, 7.5K, and 10K Bandwidth was limited and delay introduced by a PacketStorm WAN Emulator Up-to 300 msec delay, 0.1% Packet Loss for IPSI traffic and an IPSI bandwidth limitation of 128Kbps were introduced.An Radcom and an Ethereal Packet Sniffer was used to collect and analyze TCP/IP Packet data.


Example of Ethereal Statistics for 5K BHCC,0.1% Packet Loss, and BW limits of 128K


5K BHCC 0.1%Packet Loss and BW limits of 128K

X-axis is time and Y-axis is bytes

Depending on which PN was under test, we could measure IPSI BW for incoming ISDN PRI traffic terminating to local IP endpoints or measure IPSI BW for outgoing ISDN PRI traffic being generated from local IP endpoints


BHCC vs IPSI Bandwidth

The simulated call scenario is a general business case.

BHCC IPSI bandwidth is based on 150 IP endpoints originating and answering 10 second duration ISDN trunk calls.

IPSI Call Signaling Packet Traffic

020406080

100

1K 2.5K 5K 7.5K 10K

BHCC

Kbp

s


BHCC Bandwidth

BHCCPer PN

Usage Per Station Average IPSI Bandwidth (Kbps) full duplex

Average IPSI TCP/IP packets per second

1K Light Traffic 17.3 Kbps 21

2.5K 30.5 Kbps 37

5K Moderate Traffic 52.2 Kbps 61

7.5K 73.8 Kbps 85

10K Heavy Traffic 83.5 Kbps 107


Provisioning must include the Layer 2 overhead, which includes preambles, headers, flags, CRCs and ATM cell

padding and encryption overhead.

Protocol Overhead per packet

Ethernet 34 bytes

PPP 12 bytes

MLPPP 13 bytes

Frame Relay 6 or 7 bytes

ATM Varies because of padding

AES Encryption 23 bytes

Ethernet adds a 18 byte header, plus a 4 byte CRC plus an optional 4-byte 802.1Q Tag plus a 8 byte preamble for a total of up to 34 bytes per packet.Point-to-Point Protocol (PPP) adds 12 bytes of layer 2 overhead per packet.Multilink PPP adds 13 bytes per packet.Frame Relay adds 6 or 7 bytes per packet.ATM adds varying amounts of overhead depending on cell padding.IPSI encryption adds up-to 23 bytes (AES) for the encryption header and padding in addition to Layer 2 overhead.


IPSI bandwidth calculations should include the additional overhead on a per packet basis

depending on the type of WAN link.

A moderate general business traffic rate is 5K BHCC

The L2 overhead for a PPP link would be 12 bytes/packet X 61 PPS X 8 bits/byte equals 5.9 Kbps for L2 overhead

5.9 Kbps for L2 overhead + 52.2 Kbps for TCP/IP CCMS Packets equals a minimum average bandwidth requirement of 58.1 Kbps.

IPSI encryption adds up-to 23 bytes/packet X 61 PPS x 8 bits/byte equals 11.2 Kbps

Total bandwidth minimum bandwidth requirement is 58.1 Kbps + 11.2 for encryption = 69.3 Kbps


IPSI Bandwidth Provisioning

A general rule of thumb for IPSI Control traffic bandwidth allocation is to add an additional 64Kbps of signaling bandwidth to the minimum required bandwidth in order to manage peak (burst) traffic loads and either round up or down to nearest DS0.

For example; for 5K busy hour calls using encrypted PPP links to control remote port networks, as described in the previous example, you would guarantee 128Kbps (69.3Kbps + 64Kbps) for IPSI signaling bandwidth across the WAN link.

BHCC Ethernet PPP MLPPP Frame Relay1K 64Kbps 64Kbps 64Kbps 64Kbps

1K w/ encryption 64Kbps 64Kbps 64Kbps 64Kbps

2.5K w/ encryption 128Kbps 128Kbps 128Kbps 128Kbps

5K w/ encryption 128Kbps 128Kbps 128Kbps 128Kbps>=7.5K 192Kbps 192Kbps 192Kbps 192Kbps

>=7.5K w/ encryption 192Kbps 192Kbps 192Kbps 192Kbps

2.5K 128Kbps 128Kbps 128Kbps 128Kbps

5K 128Kbps 128Kbps 128Kbps 128Kbps


Standby IPSI Signaling Traffic

• In the above figure, the green line represents traffic from the standby IPSI which in turn overlaps the blue line with traffic from the standby server. As you can see there is very little traffic.

• 2.4 Kbps bandwidth is consumed by the standby IPSI.


Where does IPSI Signaling Fit?8 Class QoS Model

Higher Priority Traffic can starve equal and lower priority traffic

– Voice Bearer Traffic and IPSI Signaling Traffic currently share the same queue and compete for bandwidth within this queue

– Voice Bearer cannot Tolerate Delay or Jitter

– IPSI can tolerate up to 300 msec Delay

– Voice Quality tolerates 3% Packet Loss

– A Port Network will become unstable with greater than 3%**Packet Loss across the link

Voice

Video

H323 Call Signaling

Network Management

Critical Data

Bulk Data

Best Effort

Scavenger

** AVAYA IP VOICE QUALITY NETWORK REQUIREMENTS White Paper, Issue 3.1, April 2006.


Layer 3 Traffic ClassificationIP Precedence and DSCP

1 0 1 0 0 0 0 0 TOS = 10100000 = 160

IP Precedence = 101 = 5Precedence7 - 111 Network Ctl6 - 110 Internetwork Ctl5 - 101 Critical4 - 100 Flash Override3 - 011 Flash2 - 010 Immediate1 - 001 Priority0 - 000 Routine

Delay

0 Normal1 Minimize

Throughput

0 Normal1 Maximize

Monetary Cost0 Normal1 Minimize

Reliability

0 Normal1 Maximize

Reserved

*ALWAYS* set to zero

P P P D T R M R

VersionLength

ToS1 Byte Len …rest of the header…………….The IPV4 Header The IPV4 Header

contains a contains a ToSToS ByteByteThe first 3 bits are The first 3 bits are used for Priority.used for Priority.

DSCP uses an additional 3 bits of the ToS Byte to differentiate traffic into 64 classes


RFC 2597 Expedited Forwarding, Assured Forwarding and Best Effort Classes

Expedited Forwarding (EF) DSCP 46Provides low loss, low latency, low jitter, and assured bandwidth

Drop Preference CLASS 1 CLASS 2 CLASS 3 CLASS 4

LOW 001010 AF11 DSCP 10

010010 AF21 DSCP 18

011010 AF31 DSCP 26

100010 AF41 DSCP 34

MEDIUM 001100 AF12 DSCP 12

010100 AF 22 DSCP 20

011100 AF32 DSCP 28

100100 AF42DSCP 36

HIGH 001110 AF13DSCP 14

010110 AF23 DSCP 22

011110 AF33DSCP 30

100110 AF43 DSCP 38

Assured Forwarding Classes:Within each class, an IP packet is assigned 3 different levels of drop precedence; low,

medium and high. AF41 (drop me last) is less likely to be dropped than AF13 (drop me after BE)

Best Effort DSCP 0 - Drop me first


Congestion Avoidance and ManagementCBWFQ , LLQ , WRED

CBWFQ provides support for user-defined traffic classes. Traffic classes are defined based on match criteria including protocols, IP DSCP values and access control lists (ACLs) CBWFQ allows you to specify the exact amount of bandwidth to be allocated for a specific class of traffic. Taking into account available bandwidth on the interface, you can configure up to 64 classes and control distribution among them. Bandwidth can be assigned a percentage of total link speed or in Kbps.A FIFO queue is reserved for each class. Optional WRED can selectively discard lower priority traffic when the interface begins to get congested. The bandwidth assigned to a class is the guaranteed bandwidth delivered to the class during congestion.LLQ supports a strict priority queue for a traffic class

– LLQ gives the priority queue absolute preferential treatment over lower priority queues;

– The strict priority LLQ queue allows more than one class of traffic to be served


Cisco AutoQoS and Proposed IPSI AF Value

Voice

Video

Call Signaling

Network Management

Critical Data

Bulk Data

Best Effort

Scavenger

Voice EF 46

Video AF41

Critical Data AF21

Bulk Data AF11

Best Effort 0

Scavenger CS1

IPSI Control

Call Signaling

Network Management

AF42

AF31 or CS3

CS6


CBWFQ

There are 3 steps to configure CBWFQ

– Define your classes of traffic (classify)– Define your policies using those classes– Apply to one or more interfaces (in, out)


Classification

It is proposed to implement QoS policies that provide:

DSCP 36 (AF42) for IPSI signaling traffic. – DSCP 34 (AF41) (CS 4 Lowest Drop Preference) already reserved for

Video in Cisco AutoQoS– IPSI signaling can be assigned another DCSP value but we must

guarantee bandwidth to minimize Packet LossExpedited Forwarding - DSCP 46 - like behavior for the real-time voice Assured Forwarding (AF31) like behavior for H.323 Call Signaling Traffic

IPSI traffic classification can be performed by an S87XX/S8500 viathe change ipsi-server interface command.


ipserver-interface command

change ipserver-interface 1 Page 1 of 1

IP SERVER INTERFACE (IPSI) ADMINISTRATION - PORT NETWORK 1

IP Control? y Socket Encryption? yIgnore Connectivity in Server Arbitration? n Enable QoS? y

Primary IPSI QoS Parameters------------ --------------

Location: 1A02 Call Control 802.1p: 6Host: 172.19.27.202 Call Control DiffServ: 36

DHCP ID: ipsi-A01a

The SAT command marks traffic Server to IPSI.

Login to the IPSI; The IPSI Firmware CLI is used to mark traffic from IPSI to Server.

IPADMIN]: set diffserv 36[IPADMIN]: show qosQoS values currently in use:

VLAN tagging : onVLAN id : 0VLAN user priority : 6Diffserv value : 55

QoS values to be used after next reset:VLAN tagging : onVLAN id : 0VLAN user priority : 6Diffserv value : 36


Example Policy Configuration

Configuring QoS for VoIP on a WAN Link

class-map VoIP-Bearermatch ip dscp 46

class-map H.323-VoIP-Controlmatch ip dscp af31

class-map IPSI-Controlmatch ip dscp af42

!

policy-map QoS-Policyclass IPSI-Control

bandwidth 128 class H.323-VoIP-Bearer

priority percent 60class VoIP-Control

bandwidth percent 5class class-default

random-detect!

Classify the traffic of interest for QoS Policy

Define QoS Policy Treatment

As Percent or Kbps


Class-Based WFQ—QoS Guarantees Plus Bandwidth Efficiency

IPSI – 128 K

Each queue is separately configured for QoS LLQ guarantees no Packet Delay due to congestionWeights (CBWFQ) guarantees minimum bandwidth based on percentage of the link speed or in Kbps for congested linksUnused capacity is shared among the default classes and should be at least 25% WRED drops lower priority data traffic

– BE, AF13, AF12, AF11, AF23 ... AF31, AF43, AF42, AF41

60%

25%Data

Voice Voice –– LLQ,LLQ,

IPSI Signaling, Voice Signaling, Data: IPSI Signaling, Voice Signaling, Data: CBWFQCBWFQ

Voice

Define QoS Applications Define Bandwidth percentage (example)

Voice signaling 5%

EF

AF31

EFEF

BEBEData – default class

10%

EFEF

AF42


Extremeware QoS Profiles

Queue 802.1p Priority Value

DiffServCode Point

QP1 - Low 0 0 - 7QP2 - LowHi 1 8 - 15QP3 - Normal 2 16 - 23QP4 - NormalHi 3 24 - 31QP5 - Medium 4 32 - 39QP6 - MediumHi 5 40 - 47QP7 - High 6 48 - 55QP8 - HighHi 7 56 - 63

IPSI and Bearer will default to the same queue QP6

Traffic can be scheduled by:Queue WeightMinimum BandwidthMaximum BandwidthPriority

– 802.1p– DSCP

You can change the QoS profile assignment for each of the 64 code points using the following command:

configure diffserv examination code-point <code-point> {qosprofile} <qosprofile>


Remoted PN Design

QoS can help protect critical traffic on occasionally congested links– QoS is not a cure for really inadequate bandwidth

Good stable Hierarchical WAN Network with a redundant, high-availability design– Router Protocols configured for quick failover – Minimize short, intermittent outages < 3 sec– Converged Network Analyzer

Plan for long duration outages– Back-up Servers (ESS)– Redundant Links

Network management in place– For bandwidth reporting and capacity planning

Call Admission Control (CAC) can be administered to limit Voice Bearer bandwidth on congested links


Voice Bearer and IPSI Signaling

Voice bearer traffic should be marked with DSCP 46 (EF)Voice bearer loss should not be greater than 3% and average one-way jitter should be less than 30 milliseconds. One-way delay should be no more than 150 milliseconds. H.323 Signaling Traffic should be marked DSCP 26 (AF31)

IPSI Signaling Traffic should be marked DSCP 36 (AF42)IPSI Signaling Packet loss should not be greater than 3%IPSI Signaling traffic should be prioritized and given a guaranteed bandwidth on WAN links based on BHCC.IPSI Links should be reliable and redundant


Phase II

H.248 Gateways bandwidth requirementsRecovery testing with high number of IP phones off of one PN.Filesync and translations pushes.Steady state Annex H and other signaling impact –calculation only (unless time permits for testing).


Acknowledgements

Co-Pilot– Steve Regini

System Test– Andy Cornejo– David James– Ana Kesselring– Rob Pospisil

ATAC– Tim Kaye– Ken Lin


Additional Slides


Why is IPSI Intolerant to Packet Loss

Older VxWorks stack have “issues”related to packet retransmissionGlobal Synchronization Issue where IPSI backs-offServer requests retransmission of lost packetIPSI backs off and waits 500 msec, then 1sec, then 2 sec > 3 secAKA TCP Slow Start for congestion avoidance


QoS Design

Bearer, 1% PL, 150ms, delay, 30ms jitter

2-way 1,150,30

1-way 5%, 5 sec, ++jittter

Delay Sensitive TCP

RIP, OSPG, EIGRP,BGP

SNMP,NTP,Syslog,NFS

Locally defined – revenue driven

SAP, Oracle, Financial, SQL

Database sync, email, ftp

Non-critical, http requires 25% allocation

1% to minimally differentiate Napster, KaZaa, Gaming from BE

Documents

IPSI 20Signaling 20Bandwidth 20Requirements 20V4