Next Generation BRAS

Copyright © 2005 Juniper Networks, Inc. Proprietary and Confidential www.juniper.net 1

Next Generation BRAS

Access Technologies for Consumer Broadband

Truman BoyesProfessional Services APAC

[email protected]

2Copyright © 2005 Juniper Networks, Inc. Proprietary and Confidential www.juniper.net

Agenda Welcome.

•Where is Broadband Going?

• What Issues are we solving?• What are the methodologies that we are using to solve

these issues?•Carriers to enter voice and video market

• Digital Media Gateway• Speeds to increase ; needing more capacity…


Triple Play : VIDEO The most complex of all services.

•The most bandwidth•The most noticeable in terms of quality.

How is it delivered? Set Top Box. MS IPTV probably dominating in this area. BW 1.5-1.8Mbps for normal TV. 7-9Mbps for HD compressed.

HQOS is still extremely important for this service. It’s enabled on the BNG.


Triple Play: Video (CONT) Resources are critical when delivering video

content. •Multicast is the resources solver.

• But where do we want to save bandwidth?– As close to the customer as possible and

everywhere back to the source.• IGMP snooping in DSLAM. IGMP multicast replication in

DLSAM saves bandwidth between the BNG and DSLAM.• Allow sharing of bandwidth between unicast and

multicast traffic for access interface. (This is where HQoS can help).


Multicast - Overview

IP Backbone

• Performs Transparent IGMP Snooping. MAC filters and multicast replication

Internet Port

IPTV Port

Single M-VLAN for video channels

• RG provides a single VC connection between home and DSLAM

• IPoE and 1483B session (video/IGMP-Proxy)

VideoHead End or

ASP

ASP(e.g. IP

Telephony)

ISP(Internet)

EnterpriseVPNs

• IGMP joins received on subscriber interface

• Adjusts (unicast) VLAN shaper in QoS h-scheduler to reflect MC traffic

C-VLAN per Subscriber

Reasoning: DSL Forum base WT-101 & TR-59 compliant. Simple single VC scheme, bandwidth fully optimized and dynamically balanced. IP QoS and

stats restored. Works with PPPoE!!!

• Single M- VLAN for all requested channels, i.e.: M-VLAN carries the channels actually requested, over broadcast approach and static broadcast of top 20 groups.

DSLAM


The second function of IGMPDynamic QoS adjustment

Subscriber V

C

Multicast V

LAN

Subscriber V

LAN

3. IGMP/C-VLAN Processed

IPTVHeadendInternet

VoIP / VoD

1. IGMP(PPPoE or IPoE)

2. IGMPSnooping

5. Unicast Scheduler (C-VLAN) adjusted

7. Final MC Replication

6. MC Video Session forwarded over MC

VLAN

4. IGMP OIF map to MC-VLAN


Customer to Service Relationship If the carrier sells circuits, it may be wise to apply

the 1:1 customer to C-VLAN model. • May “map” port to C-VLAN, so customer has single VC to the

RG and single C-VLAN interface on BNG.• Easy to apply QoS to single identifier.

N:1 Model for true distinction between services. • The services run on different logical links. HQOS become an

issue. • Provisioning and Troubleshooting multiple l2 interfaces for a

single customer will prove to be a challenge.


WT-101: 1:1 VLAN Solution

IP Backbone

Internet Port

IPTV

Multi-ServiceBSRRG

VideoHead End or

ASP

DSLAMC-VLANs ASP

(e.g. IP Telephony)

ISP(Internet)

EnterpriseVPNs

• Multi-Service Edge Routing (BSR)• IP VPNs• Stacked VLANs per customer site

•VLAN auto-sensing, no OPEX• PPP and DHCP (and routed IP)

• DHCP sessions may be aggregated• Hierarchical IP QoS ; per user, per flow

VoIP

Switch

• One ATM VC per household• Usually one IP @ for consumers• Could convey 1..N PPP / DHCP sessions• IP Subnet(s) for business sites

• Can optionally support multi-VCs, with Ethernet QoS mapping (single C-VLAN).

• One C-VLAN per port• S-VLAN added by DSLAM or Aggregation

NW Node• Optional: frames marked with Eth priority

within a VLAN• Optional: Sub/Line ID• Multicast:

•IGMP Snooping•M-VLAN – N:1•Multicast Replication & x-connect

• Optional: Separate Edge for BIZ• Same as 1:1 as each port is

directed to a single edge

Optional


WT-101: N:1 VLAN Solution

Internet Port

IPTV

RG VideoHead End or

ASP

DSLAMService VLANs

ASP(e.g. IP

Telephony)

ISP(Internet)

EnterpriseVPNs

• One or more ATM VC (and IP@) per service• Internet or VPN Access• IP/Video Telephony• Broadcast TV• Video streaming (unicast)• Gaming? Storage?

• Per VC: Protocol Based X-Connect – IP or PPP (via ETHERTYPE); other RG – Marking VLAN

• ATM may be removed from the local loop (EFM)

VoIP

SwitchSwitch

Business Site

Service Node with MC

Service Node+ SBC

BRAS

Service Node• One VLAN per consumer “service”• Some QoS Semantics in VID• Some QoS Semantics in .1p

• One VLAN per business site• Mixing of VLAN schemes

• M-VLAN – N:1• Line ID via PPPoE IA & DHCP Op82

• Multiple Service Nodes or “Broadband Gateways”• QoS architecture: non standard H-QoS, DiffServ++• SLAs• Lawful intercept per BNG• Security & OAM challenges (see other slides)• Provisioning Overhead on AN, Aggregation NW, BNG


One BNG to rule them all Policy enforcement is clear with a single BNG

as access point into the SP net. Multicast / HQOS is easy (at least the

“carving” of the bandwidth between services at a single point is easy.

Lawful Intercept in a single location reduces the admin work.

What about L2C between BNG and DSLAM to obtain correct sync rates between customer and DSLAM.


Migrations from existing BRAS/ACCESS Many SP’s have ATM DSLAMs, ATM networks, that connect to MPLS/IP cores As we move to Ethernet it makes sense to use protocols that are better suited

for Ethernet: PPPoE. Why does it suite? • Client/Server instead of just point to point.• Protection on ethernet segments• Allows a move away from ATM infrastructure.

• BNGs can start to support both PPPoA and PPPoE, and of course, PPPoEoA.

• Some DSLAMS are implementing PPPoA to PPPoE translation. Be warned about MTU issues. PPPoE max MTU is 1492, many modems do not support MSS clamping, and PMTU discovery is not always going to work.

• Draft: draft-arberg-pppoe-mtu-gt1492• PPPoA ---> PPPoE -----> DHCP when possible.


If you build it they will need to be trunked VPLS/ Kompella / PWE3/ trunking of Ethernet

from some regions to a centralized BNG. Grows a network quicker in some cases. Make the choice to trunk or deploy BNG

based on population densities and what equipment/infrastructure do you have in that region.

BNG’s could also provide trunking of some traffic back to other PE.


BRAS PE Past 4-5 yrs we have been building MPLS networks

because they give us:• Fast re-route, link protection, node protection• Signaling of BW• Isolation of routing tables• BW reservations (ie. Reserve and possibly police LSP traffic

from BRAS) Why not enjoy the same benefits in BRAS networks ?

• BRAS as dual homed PE direct to P nodes. Remove dependence on existing PE’s (potentially makes these nodes *more* available)


High Availability on BRAS PPP State Replication DHCP state replication All routing protocol state preserved between routing

engines / SRPs / controllers. Software faults do happen, but can your network

handle 30k subscribers being dropped and reconnecting?

Software patches on the fly. Upgrade specific applications on BNGs, ie. DHCP local server to support new option. Moves away from monolithic operating system maintenance.


Service Activations / Alterations Now BW policy changes that are activated by a

customer through a portal.•Could be captive portal or user initiated

Service Change• 7Mbps xDSL line. Shaped to 1M. User wants to

download an ISO image; can increase service speed to line rate for period of time.

• User subscribes to policy that blocks incoming traffic at the SP.

• Could allow differentiated billing on volume for specific services. IE. Billable internet data, and all you can eat local content. Free to the provider traffic.


NGN Broadband in Summary Broadband is changing

• More services , speeds• More importance on the services

– Means more Reliability is necessary Carriers will be digital media gateways. Not the

media companies : but the ppl that bring it to you. Adoption of mechanisms like HQOS and DSLAM

multicast replication are key to scaling and guaranteeing the right delivery of service.

Resiliency is extremely important. We are spending time to build these networks. Lets built it once the right way so that it can last at least 5-6 years.

Copyright © 2005 Juniper Networks, Inc. Proprietary and Confidential www.juniper.net 17

Thank You APRICOT [email protected]


Broadband Today ADSL, Cable, WiFi, Metro Ethernet

•North America dominating cable markets but growing in DSL deployment.

•DSL in Asia / Europe / Americas•WiFi in rural areas for last mile. Also available in

highly populated areas for short range use.• 3G dedicated access to augment this WiFi market.

•Ethernet delivery is cheap, and scalable to deploy in populated areas. Connecting multi-unit buildings for residential and business customers.


WT-101 BackgroundWT-101 was born out of the desire of SP to take advantage of the benefits of Ethernet, which

are primarily cost & simplicity and which align with general move to packet based NGN

Participants actively involved SP: BT, Bellsouth, DT, FT, Telecom Italia , Singtel Vendors: Juniper, Alcatel, Cisco, Ericsson, Redback, Huawei, Fujitsu

Network Architecture Philosophy Simplest Architecture Possible (basic network design) Simple L2(-only) Access Node Edge Architectures: Single Edge, Dual Edge (Video & Other)

Multiple Edge – outside of scope, however if req, principles should be extended

Business Models Based on Multi-Service Business Requirements defined in TR-058 Additional specification in WT-102

New term in WT-101: Broadband Network Gateway (BNG) Defined as a device that implements a subset of BRAS requirements (defined in TR-092) with additional requirements in WT-101


WT-101 Overview & StatusAccess Node Port (1:1) / Protocol (N:1) based x-connect Restricted 802.1d bridging Multicast:

• IGMP: Snooping, Report Suppression/Proxy Reporting

• Multicast VLAN: replication and x-connect to Subscriber ports

IWF for PPPoA Line ID: PPPoE IA; DHCP Op82 Encapsulation & Line Params Signalling Bulk Provisioning

Ethernet Aggregation Network Only Ethernet requirements – network architecture is not

prescribed 802.1ad (S-Tag) Bridging & with restricted forwarding Support for 1:1 & N:1 VLAN Models Multicast-VLAN Simple Priority based QoS

BNG 802.1ad:

• N:1 & 1:1 support• Dual-tag push & pop• Auto-sense VLAN (dynamic) & Static VLAN

interfaces Hierarchical QoS Modular Multicast Requirements for several

deployment scenarios• Multicast-VLAN• Dynamic H-QoS adjustment• PPP or IP for Unicast• Single and Dual BNG deployments

Security: • IP Spoofing Secure ARP & DHCP Snooping• Proxy-ARP

CPE (RG) Support of Legacy CPE for Legacy Services RG requirements for new applications/services


WT-101 VLAN Architecture

Priority-Tagged Frames

101 101

S-Tag Arrangements

ResidentialSubscribers

(N:1)

A B

Access Node

EFM or ATM Single-VC

101101

101102

101101

101102

Service 1

Service 2

Service 1Service 2

Service 1

(.1p)

(.1p)

(.1p)

(.1p)Business orResidential 1:1

Unique C-Tag, Common S-Tag

S-Tag Arrangements for N:1 residential:

A – N:1 VLAN scenario where all subscribers are placed into a common VLANB – N:1 VLAN scenario where individual subscriber sessions are placed into a common

VLAN based on service type

Priority-Tagged Frames

Priority is optional. Usually wiser to not change DSL interface


Multicast - Key Attributes 1) Low Zap time (end user experience <1s, network

experience <250ms) 2) Minimize replication of multicast streams on the core network 3) No duplication of multicast streams on the access network,

• DSL line = low BW, end RG/STB can’t deal with duplicate packets 4) Redundancy 5) Ability to migrate to DSLAM IGMP-proxy or RG-Forking at a later stage 6) Dynamic QoS adjustment on IGMP report 7) Scale to multiple E320’s connected to M-VLAN (~67K subs for each E320) 8) DSL Forum - WT-101 compliant


Multicast Solutions –“Like Skinning a Cat!” 1a: IGMP to M-Series & IGMP-Proxy on E320 1b: PIM on M-Series & E320 2a: Multicast VR with IGMP-Proxy 2b: Multicast VR with PIM-SSM 2c: Only Internet VR with PIM-SSM


Single BNG – PPP – AN/RG Forking Single BNG – IPoE – H-QoS for MC

Dual BNG – IPoE – no H-QoS for MCSingle BNG – IPoE – no H-QoS for MC

WT-101 Multicast Architecture Options

BNG

RG-A2’ Copy IGMP/PPP Msg to IGMP/IPoE on M-VLAN & Snoop

1’ Copy IGMP/PPP Msg to IGMP/IPoE on VC

Unicast1:1 or N:1

M-VLANIGMP Snooping

Deliver IPmc to M-VLAN, update Unicast shaper

BNG

RG-A

Unicast1:1 or N:1

M-VLANIGMP Snooping

Deliver IPmc to M-VLAN, update Unicast shaper

Copy IGMP Msg to M-VLAN & Snoop

BNG

RG-A

Unicast1:1 or N:1

M-VLANIGMP Snooping

Deliver IPmc to M-VLAN, don’t update Unicast shaper

Copy IGMP Msg to M-VLAN, Snoop & Proxy/Suppress Reports

BNGRG-A

Unicast1:1 or N:1

M-VLAN IGMP Snooping

Copy IGMP Msg to M-VLAN, Snoop & Proxy/Suppress Reports

Deliver IPmc to M-VLAN, don’t update Unicast shaper

1 2

3 4


Reasons to go for C-VLAN Faulting / Tracking -> Ethernet OAM immature (Eth-to-ATM OAM

even worse) -> C-VLAN allows for ARP broadcast to check end-to-end connectivity

MAC spoofing -> checks/’hacks’ in DSLAMs and switches not considered as secure enough

Multi-session PPPoE -> easier to control Protocol translation -> MAC@ translation complicates DHCP

setups (MAC@ is in DHCP payload as well). L2 DSLAMs require too much complexity

Multicast -> need per-subscriber IGMP knowledge for QoS adjustments

End user id for legal interception -> easier to adapt existing system for ATM to ethernet

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