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© Verizon 2010 All Rights Reserved Page - 1
The Role of PBB in Service Provider Networks
Nick Del Regno
Principal Member of Technical Staff
Verizon Core Network Technology
© Verizon 2010 All Rights Reserved Page - 2
Agenda
Verizon Ethernet Networks
Provider Bridged Network Challenges
PBB in Native Ethernet Networks
VPLS Challenges
PBB in VPLS Networks
© Verizon 2010 All Rights Reserved
Verizon Ethernet Networks
Switched Ethernet Service
– LATA-bound Ethernet Service Network
– EVPL, EP-LAN, EVP-LAN Services
– Provider Bridging & Provider Backbone Bridging
Converged Packet Architecture
– National/Global Ethernet Service Network
– EVPL, EP-LAN & EVP-LAN Services
– VPLS & VPWS based services
End-to-End Ethernet Solutions
Page - 3
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Provider Bridging Challenges
VLAN ID Space Limitations
– 12-bits = 4096 VLANs
Customer VLAN Space Overlap
Global Nature of VLANs
– Switch
– Network
Historical lack of VLAN translation capability
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DA SAC-VLAN
Tag
Eth
ert
yp
e
Payload FCS
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Early Solutions
VLAN Stacking
– Q-in-Q
– 802.1ad
S-VLAN expands addressable VLAN space
– 16,777,216 VLANs (4096 C-Tags x 4096 S-Tags)
– Doesn’t help MAC Scaling
S-VLAN often represents customer EVC
– 4096 EVCs per network
– Too few for large SP networks
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DA SAS-VLAN
Tag
C-VLAN
Tag
Eth
ert
yp
e
Payload FCS
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Topological Considerations
Early deployments– Flat Topologies
– Tree & Branch Architectures
Hierarchy Introduced to Scale– Improves MST convergence
– Creates MAC scaling challenges
– VLAN Scaling still limited
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(Possible)
MAC Choke
Points
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Provider Backbone Bridging (802.1ah)
MAC + Tag Stack
– Backbone MACs pre-pended to packet
– B-Tag is a VLAN Tag (EtherType: 0x88A8)
– New I-Tag
• EtherType: 0x88E7
• Priority, Drop Eligibility and “Use Customer Addresses” Flags
• 24-bit Service Instance ID = 16,777,216 IDs
Introduces Backbone Tunnel Concept
– Multipoint B-VIDs for ELAN traffic
– Point-to-Point B-VIDs for ELINE traffic
Hides customer MACs
– C-MACs visible within PB switches and Backbone Edge Bridges (BEBs)
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B-DA B-SA B-Tag I-Tag C-DA C-SAC-VLAN
Tag
Eth
ert
yp
e
Payload FCS B-FCS
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PBB in Provider Bridged Networks
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Legacy
Ethernet
Switch
Legacy
Ethernet
Switch
Legacy
Ethernet
Switch
Legacy
Ethernet
Switch
Legacy
Ethernet
Switch
Legacy
Ethernet
Switch
Next Gen
Ethernet
Switch
IB-BEB IB-BEB IB-BEBIB-BEB /
BCB
BCB BCB
Legacy
Ethernet
Switch
Customer EdgeC-Tagged Packets
S-Tagged Packets
I-B Tagged Packets
BCB: Backbone Core Bridge
IB-BEB: Backbone Edge Bridge
No Customer MAC Visibility
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PBB in Provider Bridged Networks
Improved Scaling
– No Customer MAC Visibility in Network Core
– 16 Million Service IDs
– Scalable Layer 2 Solution
• MPLS/VPLS not required
Works well with Multiple Registration Protocol
– MMRP for MAC Registration
– MVRP for VLAN Registration
MSTP for Topology Management
G.8031 for P2P Tunnels
– 50mS resiliency for EVPL Traffic
Well suited for Multicast/Broadcast vs. VPLS
Simpler Evolution from PB networks vs. MPLS
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VPLS Challenges
Requires Full Mesh of LSPs– LDP or RSVP-TE
– 150 PEs results in over 22,000 LSPs
• Not to mention Fast Reroute (FRR) Bypass/Detour LSPs
Results in Full Mesh (or more) of Pseudowires
Large networks result in LSP exhaust– Especially at Transit Locations
• US <-> EMEA
• US <-> APAC
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PE
PE
PE
PE
PE
PE
PE
PE
PP
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H-VPLS Scaling Solutions
Dramatically Reduces Number of LSPs– Full Mesh Required between “MTUs”
Reduces number of Pseudowires– PWs needed only between PE & MTU and between MTUs
Creates MAC Address Choke Points– ALL Customer MACs visible at MTU
– Can approach MAC scale limits of hierarchical boundary equipment
Page - 11
PE
PE
PE
PE
PE
PE
PE
PE
MTU
MTU
MTU
MTU
All Customer
MACs visible at
MTUs
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PBB + HVPLS
Leverage HVPLS to reduce LSP & PW scale
Leverage PBB to reduce Customer MAC Scale
PBB in the PE
– Encapsulate customer traffic in PBB
– MTU Devices only bridge on Backbone MAC Address
• Similar to BCB function in Native Ethernet backbones
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PE
PE
PE
PE +
IB-BEB
PE
PE
PE
PE
MTU
MTU
MTU
MTU
No Customer
MAC visibility in
VPLS core
PE +
IB-BEB
PE +
IB-BEB
PE +
IB-BEB
PE +
IB-BEB
PE +
IB-BEB
PE +
IB-BEB
PE +
IB-BEB
© Verizon 2010 All Rights Reserved
PBB vs MPLS?
No such thing
Agnostic tool
– Helps scale native Ethernet networks
– Helps scale VPLS networks
PBB-TE vs MPLS-TP = TBD
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Questions?