IPW-5Rev1 1

Overview of Routing & Interworking Plans for Fixed & Mobile Networks

ITU-T Study Group 2 (Network & Service Operations) Question 2 (Routing)

areas of responsibility current work in progress interactions with IETF and ATMF planned activities

Gerald Ash, Rapporteur, Q.2/2

Tel: +1 732 420 4578 Fax: +1 732 368 6687

Email: gash@att.com

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Areas of Responsibility

traffic routing E.170 (Traffic Routing) E.171 (International Telephone Routing Plan) E.350 (Dynamic Routing Interworking) E.352 (Routing Guidelines for Efficient Routing Methods) E.353 -- Routing of Calls When Using International Routing Addresses

routing across circuit-based & packet-based networks E.177 (B-ISDN Routing) E.351 (Routing of Multimedia Connections Across TDM-, ATM-, & IP-

Based Networks) mobile network routing

E.173 (Routing Plan for Interconnection Between Public Land Mobile Networks and Fixed Terminal Networks)

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Current Work in Progress

E.350 -- Dynamic Routing Interworking E.351 -- Routing of Multimedia Connections Across

TDM-, ATM-, & IP-Based Networks E.352 -- Routing Guidelines for Efficient Routing

Methods E.353 -- Routing of Calls When Using International

Routing Addresses

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E.350 -- Dynamic Routing Interworking

provides for interworking among all dynamic route selection methods includes DNHR, RTNR, DCR, RINR, WIN, DAR, STR, STT, DADR, ODR, &

future methods route selection method not being standardized

recommends the signaling & information-exchange parameters required to support interworking SETUP-VDL: the via & destination switch list (VDL) parameter in the SETUP

message specifies all via switches (VSs) & destination switch (DS) in path SETUP-RES: the reservation (RES) parameter in SETUP message specifies

the level of circuit reservation applied at VSs RELEASE-CB: the crankback (CB) parameter in RELEASE message sent from

VS or DS to originating switch (OS) to allow further alternate routing at OS QUERY: provides OS to DS or OS to routing processor (RP) status request STATUS: provides OS/VS/DS to RP or DS to OS status information RECOM: provides RP to OS/VS/DS routing recommendation

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E.351 -- Routing of Multimedia ConnectionsAcross TDM-, ATM-, & IP-Based Networks

recommends established routing functionality within network type(s) for application across network types, including:

number/name translation & routing E.164-NSAP based number translation/routing applied in TDM- & ATM-based networks

routing table management automatic generation of routing tables based on network topology & status applied in TDM-,

ATM- & IP-based networks automatic update & synchronization of topology databases applied in ATM- & IP-based

networks route selection

fixed route selection applied in TDM-, ATM-, & IP-based networks dynamic route selection (event dependent, state-dependent, time-dependent) applied in

TDM-based networks QoS resource management applied in TDM-based networks

bandwidth allocation & protection applied in TDM-based networks priority routing applied in TDM-based networks priority queuing applied in ATM- & IP-based networks

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E.351 -- Routing of Multimedia ConnectionsAcross TDM-, ATM-, & IP-Based Networks (Continued)

recommends the signaling & information-exchange parameters required to support the recommended routing methods, including:

number/name translation & routing E.164-NSAP: address parameter in the connection setup information element (IE) for routing

to destination node (DN) INRA: international network routing address (INRA) parameter in setup IE for routing to DN IP-ADR: IP address (IP-ADR) parameter in setup IE for routing to DN CIC: call identification code (CIC) parameter in setup IE for routing to DN

routing table management HELLO: parameter provides for identification of links between network nodes TSE: topology-state-element (TSE) parameter provides for the automatic updating of nodes,

links, and reachable addresses in the topology database RQE: routing-query-element (RQE) parameter provides for the originating node (ON) to DN or

ON to routing processor (RP) link- and/or node-status request RSE: routing-status-element (RSE) parameter provides for a node to RP or DN to ON link

and/or node status information RRE: routing-recommendation-element (RRE) parameter provides for an RP to node routing

recommendation

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E.351 -- Routing of Multimedia ConnectionsAcross TDM-, ATM-, & IP-Based Networks (Continued)

recommends the signaling & information-exchange parameters required to support the recommended routing methods, including:

route selection DTL/ER: designated-transit-list/explicit-route (DTL/ER) parameter in the setup IE specifies each via

node (VN) and the DN in the route CBK/BNA: crankback/bandwidth-not-available (CB/BNA) parameter in the connection release IE

sent from VN to ON or DN to ON; allows for possible further alternate routing at ON QoS resource management

QoS-PAR: QoS parameter (QoS-PAR) in the setup IE includes QoS thresholds (e.g., transfer delay, delay variation, packet loss) used at VN to compare link QoS performance to requested QoS threshold

TRAF-PAR: traffic-parameter (TRAF-PAR) in the setup IE (e.g., average bit rate, maximum bit rate, minimum bit rate) used at VN to compare link characteristics to requested TRAF-PAR thresholds

DoS: depth-of-search (DoS) parameter in the setup IE used at VN to compare link load state to allowed DoS threshold

MOD: modify (MOD) parameter in the setup IE used at VN to modify existing traffic parameters on an existing connection

DIFFSERV: differentiated-services (DIFFSERV) parameter is used to designate the relative priority and management policy of queues

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E.352 - Routing Guidelines for Efficient Routing Methods

recommends use of dynamic bandwidth reservation on shortest paths to maintain efficient bandwidth use and throughput prevents inefficient routing under congestion which can lead to

network instability and drastic throughput loss recommends use of event-dependent routing (EDR) path selection

methods to reduce flooding overhead and maintain performance provides alternative to state-dependent routing (SDR) path

selection with flooding/LSAs which can lead to large processing overheads and smaller area/AS size

illustrates use of dynamic bandwidth reservation & EDR methods plan to extend to recommendations applicable to packet network traffic-

engineering/management such as MPLS/traffic-engineering

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E.353 - Routing Calls when Using International Network Routing Addresses

recommends an addressing plan for routing calls based on E.164 number translation to an international network routing address avoids work-around for using E.164 numbers as routing addresses avoids unnecessary allocation of E.164 numbers for routing purposes provides originating network identification useful for routing (e.g., based on language of

originating user) addressing plan & formats being worked jointly with numbering question (Q 1/2) defines an international network routing address (INRA) format

serving network translates E.164 -> INRA format includes a 3-digit country code, a 5-digit network routing address (NRA), and a 2-

digit sub-address NRA identifies service provider network

defines a serving network identification code (SNID) format uses same format as INRA NRA identifies the serving network

recommends that INRA, SNID, and dialed number (DN) be carried within separate information elements in the call setup message

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Interactions with IETF and ATMF Based on Recommendation E.351 (Routing of Multimedia

Connections Across TDM-, ATM-, and IP-Based Networks)

5 drafts submitted to IETF presentations made to IETF Routing Area (1), MPLS working group (2)

has led to positive discussions & collaborations with IETF routing experts

has led to bandwidth-modification & priority-routing functionality in MPLS protocol RFCs

3 contributions submitted to ATMF presentations made to ATMF routing/addressing & control signaling

(RA/CS) working group (1), ATMF traffic management (TM) working group has led to positive discussions & collaborations with ATMF routing

experts has led to bandwidth-modification & priority-routing functionality in

UNI/PNNI/AINI protocol specifications

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Interactions with IETF Based on Recommendation E.351

QoS Resource Management <Reference: draft-ash-itu-sg2-qos-routing-02.txt>

capabilities allows integration of network services provides automatic bandwidth allocation & protection provides service differentiation (e.g., priority routing services such as 800

gold & international priority routing) queuing priority applied to achieve service differentiation

analogous methods applied in PSTNs with TDM technology over the past decade improved performance quality & reliability additional revenue & revenue retention reduced operations & capital cost allows fast feature introduction with standardized routing platform

has led to needed MPLS extensions <draft-ietf-mpls-crlsp-modify-00.txt> <draft-ietf-mpls-cr-ldp-03.txt>

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Interactions with IETF and ATMF Based on Recommendation E.352 (Routing Guidelines for

Efficient Routing Methods)

draft submitted to IETF presentations made to MPLS working group (1) & traffic-

engineering working group (1) has led to positive discussions & collaborations with IETF

routing experts proposed next steps

include guidelines in Traffic Engineering Framework draft provide comprehensive informational draft on TE & QoS

methods for multiservice networks include guidelines in IGP TE requirements, as appropriate use guidelines to define any needed MPLS/TE MIB objects,

as appropriate

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Planned Activities

traffic-engineering/management methods for new network applications & technologies provide comprehensive contributions/drafts on traffic-engineering & QoS

methods for multiservice networks support new service applications, such as multimedia, on an integrated,

shared network support new technologies such as IMT-2000

dynamic routing methods for new network applications & technologies provide needed extensions to IP-, ATM-, and TDM-based capabilities to

support QoS, performance, & other needs for new applications & technologies

intelligent network (IN) routing methods for new network applications & technologies provide needed extensions to IP-, ATM-, and TDM-based capabilities to

support IN routing capabilities for new applications & technologies

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Planned Activities (continued)

mobile routing extensions reflect issues such as tracking of routing address mapping of E.164

numbers/names to IP addresses reflect interworking of fixed, wireless, and portable terminals across

various technologies, including IP-, ATM-, & TDM-based networks complement existing recommendations on mobile system identity

and global title derivation (E.212/E.214) open routing application programming interface (API)

address the connection management routing parameters which need to be controlled through an applications interface

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Backup Slides

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Example of Multimedia Connection Across TDM-, ATM-, & IP-Based Networks

need for standard routing functionality between networks (includes addressing, route selection, QoS resource management, signaling/information exchange)

extend established routing methods for application across network types & within TDM-, ATM, & IP-based PSTNs

PC PC

TDM-BASED NETWORK A

a2

IP-BASED NETWORK B

ATM-BASED NETWORK C

a1 c2

c1

b2

b1

b2

b1

a3

Switch/Router

Gateway Switch/Router

LEGEND

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TDM-Based Routing Experience Applicable to E.351

dynamic path selection state-dependent routing (SDR), event-dependent routing (EDR), & time-

dependent routing (TDR) path selection widely implemented applied in national, international, metropolitan area, & private networks applied successfully to large fraction of PSTN traffic over past 2 decades dynamic bandwidth reservation important for network stability event dependent path selection (e.g., success to the top) can be nearly as

effective as state dependent path selection, but simpler crankback very efficient in path selection & replaces need for real-time link

state flooding achieves improved performance at lower cost

QoS resource management provides automatic bandwidth allocation, bandwidth protection, & priority

routing used successfully in PSTNs over the past decade

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TDM-Based Routing Experience Applicable to E.351

benefits of dynamic path selection & QoS resource management performance quality (reduced blocking, improved reliability,

robustness to failure, reduced connection set-up delay, improved transmission quality)

service flexibility (fast feature introduction with standardized routing platform, capacity sharing among services on integrated network, new differentiated (e.g., priority routing) services introduced)

additional revenue & revenue retention (increased call completions, reliability protects of revenue at risk, new services such as priority routing)

cost reduction (lower transmission & switching costs with advanced design, lower operations expense with automated, centralized operations, lower capacity churn, automatic routing administration)

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IP- & ATM-Based Routing Experience Applicable to E.351

standards-based protocols for routing, signaling, provisioning (OSPF, BGP, MPLS, PNNI, etc.) signaling supports source routing with DTL/ER & crankback signaling supports QoS routing functionality

network operations automatic provisioning of links, switches, reachable addresses (with

OSPF, PNNI, etc.) network provisioning & maintenance benefits from fewer links in

sparse network topology voice, data, multimedia service integration

achieved with IP- & ATM-based routing protocols

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IP- & ATM-Based Routing Experience Applicable to E.351

network efficiency sparse topology & flat-network routing take advantage of lower

costs of hi-speed (OC3/OC12/OC48) transport links & switch terminations

sparse hi-speed-link design has economic benefit (20-30%) compared to mesh-based design

network performance sparse hi-speed-link design has some performance benefit under

overload due to full sharing of network capacity

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Illustrative QoS Resource Management Method

distributed method applied on a per-virtual-network basis ingress LSR (ILSR) allocates bandwidth to each virtual-network (VN)

based on demand for VN bandwidth increase

ILSR decides link-bandwidth-modification threshold (Pi) based on

– bandwidth-in-progress (BWIP)– routing priority (key, normal, best-effort)– bandwidth allocation BWavg– first/alternate choice path

ILSR launches a CRLDP label request message with explicit route, modify-flag, traffic parameters, & threshold Pi (carried in setup priority)

VOICE

ISDN DATAWIDEBAND

VOICE

ISDN DATAWIDEBAND

ILSR VLSR ELSR

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Illustrative QoS Resource Management Method (continued)

via LSRs (VLSRs) keep local link state of idle link bandwidth (ILBW), including lightly loaded (LL), heavily loaded (HL), reserved (R), & busy (B)

VLSRs compare link state to Pi threshold VLSRs send bandwidth-not-available notification message to ILSR if Pi

threshold not met

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Example for CRLSP Bandwidth Modification

A C D EE

A B EE

A to E Routing

EA D

B

C

LL

LL HL

R

LL

LL R

LL LLHL