1. MAC-in-MAC and Transport Scenarios Paul Buttorf, Michael Chen, Dirceu Cavendish, Marcus Holness, Pankaj Jha, Kshitij Kumar, Dinesh Mohan, Himanshu Shah, Arnold Sodder, Joris Wils

2. Agenda Service Provider Transport Scenarios –Flat network architecture –Q-in-Q network architecture –MAC-in-MAC network architecture Service Provider Hierarchical Architecture

3. Reference Provider Transport Architecture Provider Network CE PE Regular bridges Customer Network RB

4. Number of MAC Addresses on flat network

5. Transport on Flat Network The example shows four scenarios. The first two are of a provider interconnecting the LANs of 5 customer sites per vlan. The last two are of a provider interconnecting customer routers. The number of MAC addresses can easily climb into the 100,000s. –Large FWD tables –Management Issues MAC address space (customer) VLAN tag space (customer, provider)

6. Number of MAC Addresses with Q-in-Q

7. With Q-in-Q The number of MAC addresses can easily climb into the 100,000s. –Large FWD tables –Protocol issues E.g. BPDU encapsulation –Management issues E.g. unreliable customer links. Limit on number of service instances (4094)

8. Number of MAC Addresses with MAC-in-MAC * Worst case scenario *

9. Hierarchical Transport Architectures MAC-in-MAC Q-in-Q CE Q-in-Q CE Q-in-Q MAC-in-MAC CE MAC-in-MAC CE Aggregation (1G uplinks, 10/100M access links) Core (10G links) Aggregation (1G uplinks, 10/100M access links)

10. Number of MAC Addresses with MAC-in-MAC + Q-in-Q

11. Number of MAC Addresses with MAC-in-MAC Equals the number of PEs regardless of the number of vlans and customer MAC addresses, because: –MAC-in-MAC bridges only need to learn the MAC addresses of PE Bridges. –Number of MAC addresses to be managed by providers unlikely to go above 1,000s.

12. Provider Transport Technologies MAC-in-MAC Q-in-Q CE MAC-in-MACQ-in-Q

13. Additional MAC-in-MAC Features Trouble free provider protocols –Special MAC addresses mean the same for customer and provider domains. –Transparent transport of control traffic –Customer topology changes do not affect provider MAC learning - No need for MAC unlearn messages Full isolation from customers (R)STP (single homed). Provider Bridges addresses can be configured local MAC addresses.

14. Final remarks Message –MAC-in-MAC is an attractive technology with unique characteristics, besides Q-in-Q for Ethernet Service Providers. Open Issue –Where is it most appropriate to use Q-in-Q and MAC-in-MAC in a Hierarchical L2 Network.

15. Hierarchical Transport Arch MAC-in-MAC core domain surrounded by Q-in-Q access domains. –Removes need for global Q-tag management Locally convert MAC-in-MAC service tag to local Q-tag –Reduces number of MAC addresses seen by MAC-in-MAC domain to number of Q-in-Q domains, I.e. < 1,000

16. Use of VPLS

17. Why Not VPLS End-to-End? VPLS has scalability issues –E.g. to connect 5 PE devices requires 20 LSPs, 40 PEs: 1,536. –Large bandwidth loss due to broadcast retransmissions. VPLS requires new features –Protection, OAM, discovery: still to be defined