MSAN access & interconnectionConsult21 Industry Working Group

10 Jan 2005

AIMS AND AGENDA

• Positioning of this Industry Working Group and of this specific meeting

• Architecture presentation and discussion (BT)

­ in­response­to­industry­input

• Industry presentation(s) and discussion

• Summary and next steps

SCOPE OF MEETING• To explore platform implications of ‘MSAN

interconnect’ to inform scheduled product working group discussions

• To reach a shared understanding of:

­ possible­architectures

­ platform­implications

­ relative­cost­impact­on­products

• Consultation in parallel with Ofcom consultation

• BT believes this to be a product cost management rather than an engineering problem

CONSULT21 FEEDBACK

• Views of infrastructure players:

­ don’t­wish­to­be­restricted­by­BT’s­design­or­preferences

­ for­any­site,­want­prices­for­MSAN­access­or­interconnect­products­for­all­services­(broadband,­PPCs,­PSTN­voice)

­ where­they­have­their­own­backhaul,­they­want­to­use­it­for­all­services­(LLU,­broadband,­PPCs,­PSTN­voice)

­ ‘Equivalence­of­input’­regulatory­principle

• Scenarios drawn up with infrastructure players

• BT to provide cost implications of scenarios to give a feel for viability

For­discussion­purposes­only.No­implementation­assurance­implied­or­intended

Service­control

Service­control

Interconnect

ContentContent­provider­-­access­to­end­user

BRASISP­-­access­to­end­user

Example­of­dial­IP

PSTN­provider­-­access­to­end­user

End­user

Switch Switch

Router

Router

What is Interconnect? What is Access?• ‘Interconnect’ is between peer-level service control and

switching / routing functions

­ the­control­protocol­needs­to­be­defined­(eg,­ISUP,­SIP-I)

• ‘Access’ is the media and control protocol paths between the end user and the service PoP

MSAN

OCP BT

Subtended­aggregator­site

Aggregatorsite

Metrosite

SoftSwitch

L2 Aggregator access

L3 Aggregator access

Physical media access (LLU)

L3 Metro interconnect

DSLAM

To­CoreSoftSwitch

BRASL3 Metro RouterRouter

Router

Switch

HDF

Remote MSAN

Main­Distribution­Frame

End­user End­user

ACCESS & INTERCONNECT PLATFORM SCENARIOS

Copper shelf

L2 Aggregator

L3 Aggregation Router

L2 switchSwitchL2 Metro access

For­discussion­purposes­only.No­implementation­assurance­implied­or­intended

SOFT LLU - OFCOM DIAGRAM

Fibre­access

BT­network

Altnet­networkAggregationdevice

MSAN

MSAN

MSAN

Copper­loops

Copper­loops

Copper­loops

Altnet­tunnel

BT­tunnel

Logical Schematic of Proposed Soft LLU from OFCOM

INTERCONNECT REALITIES

• What are the realities of today’s interconnect?

­ Regulatory­drive­for­infrastructure­competition­and­build-out

­ LLU­provides­ultimate­opportunity­for­infrastructure­competition­for­current­and­next-generation­network­applications

­ OCPs­typically­apply­a­logical­process­to­make­‘build­versus­buy’­decisions­in­network­expansion

RELATIVE COSTINGS

• No access

• Broadband / data-only access

• Broadband / data and PSTN voice access

• Relative cost cf with overall network

Base­case

Cost­of­additional­ports­for­OCP­connect­+­cost­

of­L2­switching­

As­(2)­+­L3­routing­+­MGW­at­MSAN

COSTING SCENARIOS• Need to recognise that all sites are not equal…

• Scenarios addressed:

­ MSAN­is­one­of­top­100­(Metro­location)

• NB­No­commercial­advantage­if­co-located­!

­ MSAN­is­in­range­100-2000­(Likely­LLU­site)

• The­most­critical­to­understand

­ MSAN­is­in­range­2000+­(unlikely­LLU­site)

• Costs­likely­to­be­disproportionately­larger

• Build as incremental cost on a nominal “base case”

­ potentially­very­low­for­L2­access

­ Higher­for­L3­access­(Router,­MGW,­etc)

• For each scenario – assume a realistic number of customer lines, and OCP interconnects (5 OCPs at each MSAN ?)

MSAN

ToBT

CopperShelf

CopperShelf

FibreShelf

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:

­ MSAN­is­one­of­top­100­

­ MSAN­is­in­range­100-2000

­ MSAN­is­in­range­2000+

Indicates­additional­component­required(over­and­above­current­21CN­Architecture)

MSAN

ToOCP

ToBT

CopperShelf

CopperShelf

FibreShelf

L2 switch

For­discussion­purposes­only.No­implementation­assurance­implied­or­intended

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 = 1+x units

• Costing scenarios:

­ MSAN­is­one­of­top­100

• No­additional­functionality­required­-­apart­from­additional­ports.­

­ MSAN­is­in­range­100-2000

• No­additional­functionality­required­-­apart­from­additional­ports.­

­ MSAN­is­in­range­2000+

• Will­require­L2­switching­capability­–­requires­additional­fully­functional­Fibre­box­at­some­locations.

MSAN

ToOCP

ToBT

CopperShelf

CopperShelf

MediaServer

Router

FibreShelf IP

BGW

Indicates­additional­component­required(over­and­above­current­21CN­Architecture)

For­discussion­purposes­only.No­implementation­assurance­implied­or­intended

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.

Ethernet­interface­aggregating­all­voice­traffic.­

Connected­to­fibre­box­due­to­port­and­functionality­limitations­within­copper­element.­

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 = 1+x+y units

• Costing scenarios:

­ MSAN­is­one­of­top­100

• Capability­should­already­be­available­at­Metro­node­ie­no­additional­cost­(?)

­ MSAN­is­in­range­100-2000

• Will­require­capability­highlighted­in­orange­plus­fibre­MSAN­ports

­ MSAN­is­in­range­2000+

• Will­require­capability­highlighted­in­orange­plus­fibre­MSAN­capability­at­some­locations­plus­ports

MSAN

ToOCP

ToBT

CopperShelf

CopperShelf

MediaServer

Router

FibreShelf IP

BGW

Indicates­additional­component­required(over­and­above­current­21CN­Architecture)

For­discussion­purposes­only.No­implementation­assurance­implied­or­intended

RELATIVE COSTS FOR PSTN VOICE ACCESS• The following is capex only

­ covers­costs­of­router­and­session­border­control­with­redundancy

­ excludes­media­server­and­OCP­fibre­ports

­ based­on­indications­from­vendors­-­subject­to­change

• Does not include opex costs

For­discussion­purposes­only.No­implementation­assurance­implied­or­intended

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5000 10000 15000 20000 25000 30000 35000 40000 45000 50000

Number of lines per MSAN site

Rat

io o

f M

SA

N c

apex

wit

h P

ST

N

voic

e ac

cess

to

no

acc

ess

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

For­discussion­purposes­only.No­implementation­assurance­implied­or­intended