Overview of Routing

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 [phone] Fax [phone]
• Email gash_at_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

4
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 -gt 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 ltReference
draft-ash-itu-sg2-qos-routing-02.txtgt

• 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
• ltdraft-ietf-mpls-crlsp-modify-00.txtgt
• ltdraft-ietf-mpls-cr-ldp-03.txtgt

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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
IP-BASED NETWORK B

• 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

TDM-BASED NETWORK A
ATM-BASED NETWORK C
a2
c1
a1
a3
c2
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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
VOICE
VOICE
ISDN DATA
ISDN DATA
ILSR
VLSR
ELSR
WIDEBAND
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)

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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