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
IPW-5Rev1
1
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 Connections
Across 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 Connections
Across 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 Connections
Across 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 trafficengineering/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) & trafficengineering 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
15
Example of Multimedia Connection
Across TDM-, ATM-, & IP-Based Networks
IP-BASED NETWORK B
b2
b2
b1
b1
TDM-BASED NETWORK A
ATM-BASED NETWORK C
a2
a1
PC
c1
a3
c2
LEGEND
PC
Switch/Router
Gateway Switch/Router
 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
16
TDM-Based Routing Experience Applicable to E.351
 dynamic path selection
 state-dependent routing (SDR), event-dependent routing (EDR), & timedependent 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
17
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)
18
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
19
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
20
Illustrative QoS Resource Management Method
VOICE
ILSR
ISDN DATA VLSR
WIDEBAND
VOICE
ISDN DATA ELSR
WIDEBAND
 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)
21
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
22
Example for CRLSP Bandwidth Modification
A
LL
C
HL
LL
D
LL
E
R
B
A to E Routing
A
A
LL
LL
R
B
HL
C
E
LL
D
E
23