MSAN access

1

• MSAN access interconnection
• Consult21 Industry Working Group
• 10 Jan 2005

2
AIMS AND AGENDA

• Positioning of this Industry Working Group and of
  this specific meeting
• Architecture presentation and discussion (BT)
• in response to industry input
• Industry presentation(s) and discussion
• Summary and next steps

3
SCOPE OF MEETING

• To explore platform implications of MSAN
  interconnect to inform scheduled product working
  group discussions
• To reach a shared understanding of
• possible architectures
• platform implications
• relative cost impact on products
• Consultation in parallel with Ofcom consultation
• BT believes this to be a product cost management
  rather than an engineering problem

4
CONSULT21 FEEDBACK

• Views of infrastructure players
• dont wish to be restricted by BTs design or
  preferences
• for any site, want prices for MSAN access or
  interconnect products for all services
  (broadband, PPCs, PSTN voice)
• where they have their own backhaul, they want to
  use it for all services (LLU, broadband, PPCs,
  PSTN voice)
• Equivalence of input regulatory principle
• Scenarios drawn up with infrastructure players
• BT to provide cost implications of scenarios to
  give a feel for viability

5
What is Interconnect? What is Access?

• Interconnect is between peer-level service
  control and switching / routing functions
• the control protocol needs to be defined (eg,
  ISUP, SIP-I)
• Access is the media and control protocol paths
  between the end user and the service PoP

Example of dial IP
Content
Content provider - access to end user
End user
Router
BRAS
ISP - access to end user
Router
Service control
Service control
PSTN provider - access to end user
Switch
Switch
Interconnect
For discussion purposes only.No implementation
assurance implied or intended
6
ACCESS INTERCONNECT PLATFORM SCENARIOS
BT
OCP
To Core
Soft Switch
Soft Switch
Metro site
L3 Metro interconnect
BRAS
L3 Metro Router
Router
L2 Metro access
Switch
L2 switch
L3 Aggregator access
L3 Aggregation Router
Router
Aggregator site
L2 Aggregator access
MSAN
L2 Aggregator
Switch
Copper shelf
DSLAM
Physical media access (LLU)
HDF
Main Distribution Frame
Subtended aggregator site
Remote MSAN
End user
End user
For discussion purposes only.No implementation
assurance implied or intended
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SOFT LLU - OFCOM DIAGRAM
Logical Schematic of Proposed Soft LLU from OFCOM
8
INTERCONNECT REALITIES

• What are the realities of todays interconnect?
• Regulatory drive for infrastructure competition
  and build-out
• LLU provides ultimate opportunity for
  infrastructure competition for current and
  next-generation network applications
• OCPs typically apply a logical process to make
  build versus buy decisions in network expansion

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RELATIVE COSTINGS
Base case
Cost of additional ports for OCP connect cost
of L2 switching

• No access
• Broadband / data-only access
• Broadband / data and PSTN voice access
• Relative cost cf with overall network

As (2) L3 routing MGW at MSAN
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COSTING SCENARIOS

• Need to recognise that all sites are not equal
• Scenarios addressed
• MSAN is one of top 100 (Metro location)
• NB No commercial advantage if co-located !
• MSAN is in range 100-2000 (Likely LLU site)
• The most critical to understand
• MSAN is in range 2000 (unlikely LLU site)
• Costs likely to be disproportionately larger
• Build as incremental cost on a nominal base
  case
• potentially very low for L2 access
• Higher for L3 access (Router, MGW, etc)
• For each scenario assume a realistic number of
  customer lines, and OCP interconnects (5 OCPs at
  each MSAN ?)

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LOGICAL FUNCTIONS INSIDE MSAN - NO ACCESS

• Copper Shelf Fibre Shelf Currently proposed
  MSAN components
• No OCP connection direct to MSAN, no additional
  gateways
• OCP connection at Metro node with
  connectivity provided by MSAN if needed
• Relative cost of providing this 1 unit
• Costing scenarios
• MSAN is one of top 100
• MSAN is in range 100-2000
• MSAN is in range 2000

MSAN
Copper Shelf
Copper Shelf
Fibre Shelf
To BT
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LOGICAL FUNCTIONS INSIDE MSAN - BROADBAND /
DATA-ONLY ACCESS

• Layer 2 switch - at MSAN sites that would
  otherwise only offer basic SDH functionality
  this could be a separate device or fully
  functional fibre box
• L2 OCP connection at MSAN
• L2 turnaround within MSAN infrastructure
• Relative cost of providing this 1x units
• Costing scenarios
• MSAN is one of top 100
• No additional functionality required - apart from
  additional ports.
• MSAN is in range 100-2000
• No additional functionality required - apart from
  additional ports.
• MSAN is in range 2000
• Will require L2 switching capability requires
  additional fully functional Fibre box at some
  locations.

MSAN
Copper Shelf
Copper Shelf
L2 switch
Fibre Shelf
To OCP
To BT
Indicates additional component required(over and
above current 21CN Architecture)
For discussion purposes only.No implementation
assurance implied or intended
13
LOGICAL FUNCTIONS INSIDE MSAN - PSTN VOICE ACCESS

• Router capable of handling ALL voice traffic at
  an MSAN, call by call routing required
• IP BGW Border Gateway. Provided as one per OCP.
  Shown connected via Fibre Shelf, but could be a
  direct GE connection to an OCP
• Media Server provides announcement capabilities
  including 3 party call with one BT one OCP
  parties (Otherwise, traffic would need to be
  backhauled to Metro node for these services
  which defeats the lowest backhaul cost argument).
  BT is also required to provide a specific
  announcement when OCP connections are busy,
  indicating that the call is unable to be
  connected due to congestion on the BT network.

Connected to fibre box due to port and
functionality limitations within copper element.
MSAN
Copper Shelf
Copper Shelf
Media Server
Ethernet interface aggregating all voice traffic.
Router
Fibre Shelf
IP BGW
To OCP
To BT
Indicates additional component required(over and
above current 21CN Architecture)
For discussion purposes only.No implementation
assurance implied or intended
14
COSTING SCENARIO - PSTN VOICE ACCESS

• L2 OCP connection at MSAN
• L2 turnaround within MSAN infrastructure
• No requirement to support local call control
  under MSAN isolation
• NB L2 switching component removed for clarity
  still required for Data and Broadband access
• Relative cost of providing this 1xy units
• Costing scenarios
• MSAN is one of top 100
• Capability should already be available at Metro
  node ie no additional cost (?)
• MSAN is in range 100-2000
• Will require capability highlighted in orange
  plus fibre MSAN ports
• MSAN is in range 2000
• Will require capability highlighted in orange
  plus fibre MSAN capability at some locations plus
  ports

MSAN
Copper Shelf
Copper Shelf
Media Server
Router
Fibre Shelf
IP BGW
To OCP
To BT
Indicates additional component required(over and
above current 21CN Architecture)
For discussion purposes only.No implementation
assurance implied or intended
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RELATIVE COSTS FOR PSTN VOICE ACCESS

• The following is capex only
• covers costs of router and session border control
  with redundancy
• excludes media server and OCP fibre ports
• based on indications from vendors - subject to
  change
• Does not include opex costs

For discussion purposes only.No implementation
assurance implied or intended
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CONCLUSION

• MSAN interconnect is technically possible,
  commercial issues dominate
• Broadband / data-only access needs no additional
  functionality for the top 2000 MSAN sites, apart
  from additional fibre ports
• PSTN voice access needs significant additional
  functionality, adding over 50 to the capital
  costs of MSANs for 30000-line sites

For discussion purposes only.No implementation
assurance implied or intended