MAC-in-MACand Transport Scenarios

Paul Buttorf, Michael Chen, Dirceu Cavendish, Marcus Holness, Pankaj Jha, Kshitij Kumar,

Dinesh Mohan, Himanshu Shah, Arnold Sodder, Joris Wils

Agenda

• Service Provider Transport Scenarios– Flat network architecture– Q-in-Q network architecture– MAC-in-MAC network architecture

• Service Provider Hierarchical Architecture

Reference Provider Transport Architecture

Provider Network

CE CE CECE

PE PE

Regular bridges

Customer Network

Customer Network

RB

RB

Number of MAC Addresseson flat network

Customer Sites per Service Instance

Mac Addresses per Customer Site

Number of Service Instances

Number of Mac Addresses

5 1,000 100 500,0005 1,000 1,000 5,000,000

20 2 10,000 400,00040 2 20,000 1,600,000

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 100,000’s.– Large FWD tables– Management Issues

• MAC address space (customer)• VLAN tag space (customer, provider)

Number of MAC Addresseswith Q-in-Q

Customer Sites per Service Instance

Mac Addresses per Customer Site

Number of Service Instances

Number of Mac Addresses

5 1,000 100 500,0005 1,000 1,000 5,000,000

20 2 10,000 400,00040 2 20,000 1,600,000

With Q-in-Q

• The number of MAC addresses can easily climb into the 100,000’s.– Large FWD tables– Protocol issues

• E.g. BPDU encapsulation

– Management issues• E.g. unreliable customer links.

• Limit on number of service instances (4094)

Number of MAC Addresseswith MAC-in-MAC

Customer Sites per Service Instance

Mac Addresses per Customer Site

Number of Service Instances

Number of Mac Addresses

5 1,000 100 5005 1,000 1,000 5,000

20 2 10,000 200,00040 2 20,000 800,000

* Worst case scenario

*

Hierarchical Transport Architectures

MAC-in-MAC

Q-in-Q

CE CE

Q-in-Q

CE CE

Q-in-Q

MAC-in-MAC

CE CE

MAC-in-MAC

CE CEAggregation (1G uplinks, 10/100M access links)

Core (10G links)

Core (10G links)

Aggregation (1G uplinks, 10/100M access links)

Number of MAC Addresseswith MAC-in-MAC + Q-in-Q

Customer Sites per Service Instance

Mac Addresses per Customer Site

Number of Service Instances

Number of Cust Sites per Q-in-Q Domain

Number of Mac Addresses

5 1,000 100 100 55 1,000 1,000 100 50

20 2 10,000 1,000 20040 2 20,000 1,000 800

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.

Provider Transport Technologies

MAC-in-MACQ-in-Q

CE CE CECE CE CE CE

CE

CE CE CECE

MAC-in-MACQ-in-Q

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 customer’s (R)STP (single

homed).• Provider Bridges’ addresses can be configured

local MAC addresses.

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.