Transcript MSAN interconnect

MSAN access &
interconnection
Consult21 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)
- in response to industry input
• 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:
- 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
CONSULT21 FEEDBACK
• Views of infrastructure players:
- don’t wish to be restricted by BT’s 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
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
End
user
Content
Content provider - access to end user
Router
BRAS
ISP - access to end user
Router
PSTN provider access to end user
Service
control
Service
control
Switch
Switch
Interconnect
For discussion purposes only.
No implementation assurance implied or intended
ACCESS & INTERCONNECT
PLATFORM SCENARIOS
BT
OCP
Soft
Switch
To Core
Soft
Switch
L3 Metro interconnect
Router
BRAS
L3 Metro Router
Metro
site
L2 Metro access
Switch
L2 switch
Router
L3 Aggregator
access
L3 Aggregation
Router
Aggregator
site
L2 Aggregator access
L2 Aggregator
Switch
Copper shelf
DSLAM
HDF
Physical media
access (LLU)
MSAN
Main Distribution Frame
Remote MSAN
For discussion purposes only.
No implementation assurance implied or intended
End user
End user
Subtended
aggregator site
SOFT LLU - OFCOM DIAGRAM
Copper loops
MSAN
Altnet tunnel
Copper loops
MSAN
BT tunnel
Aggregation
device
Altnet network
BT network
Copper loops
MSAN
Fibre access
Logical Schematic of Proposed Soft LLU from OFCOM
INTERCONNECT REALITIES
• What are the realities of today’s 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
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
As (2) + L3 routing +
MGW at MSAN
•
Relative cost cf with overall network
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 ?)
LOGICAL FUNCTIONS INSIDE
MSAN - NO ACCESS
MSAN
Copper
Copper
Shelf
Shelf
• 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
Fibre
Shelf
To
BT
• 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+
LOGICAL FUNCTIONS INSIDE
MSAN - BROADBAND / DATA-ONLY
• Layer 2 switch - at MSAN sites that would otherwise only
ACCESS
offer basic SDH functionality – this could be a separate
MSAN
Copper
Copper
Shelf
Shelf
device or fully functional fibre box
• L2 OCP connection at MSAN
• L2 turnaround within MSAN infrastructure
• Relative cost of providing this = 1+x units
L2
switch
• Costing scenarios:
-
• No additional functionality required - apart from
additional ports.
Fibre
Shelf
To
BT
MSAN is one of top 100
MSAN is in range 100-2000
• No additional functionality required - apart from
additional ports.
To
OCP
Indicates additional component
required(over and above current
21CN Architecture)
-
MSAN is in range 2000+
• Will require L2 switching capability – requires additional
fully functional Fibre box at some locations.
For discussion purposes only.
No implementation assurance implied or intended
LOGICAL FUNCTIONS INSIDE MSAN
- PSTN VOICE ACCESS
MSAN Connected to
Copper
Copper
Shelf
Shelf
Ethernet
interface
aggregatin
g all voice
traffic.
Media
Server
fibre box due
to port and
functionality
limitations
within copper
element.
Router
Fibre
Shelf
To
BT
IP BGW
To
OCP
Indicates additional component
required(over and above current
21CN Architecture)
• 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.
For discussion purposes only.
No implementation assurance implied or intended
COSTING SCENARIO - PSTN VOICE
• L2 OCP connection at MSAN
ACCESS
• L2 turnaround within MSAN infrastructure
MSAN
Copper
Copper
Shelf
Shelf
• No requirement to support local call control
under MSAN isolation
Media
Server
• NB: L2 switching component removed for
clarity – still required for Data and Broadband
access
Router
• Relative cost of providing this = 1+x+y units
• Costing scenarios:
Fibre
Shelf
To
BT
- MSAN is one of top 100
IP BGW
• Capability should already be available at Metro
node ie no additional cost (?)
- MSAN is in range 100-2000
To
OCP
• Will require capability highlighted in orange plus
fibre MSAN ports
- MSAN is in range 2000+
Indicates additional component
required(over and above current
21CN Architecture)
• Will require capability highlighted in orange plus
fibre MSAN capability at some locations plus ports
For discussion purposes only.
No implementation assurance implied or intended
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
Ratio of MSAN capex with PSTN
voice access to no access
• Does not include opex costs
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
5000 10000 15000 20000 25000 30000 35000 40000 45000 50000
Number of lines per MSAN site
For discussion purposes only.
No implementation assurance implied or intended
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