Summary
Pure Layer 2 and 802.1q tunneling network architectures offer practical solutions for enterprises that are looking to receive and service providers that are looking to offer Metro Ethernet connectivity. Examine carefully the inherent limitations of pure Layer 2 implementation if you are considering this type of service and creating its design. Even though enterprises have moved on from pure Layer 2 networks to those that are Layer 3 switched, Layer 2 still holds a great value for an Ethernet solution for a service provider. Many enterprises and service providers are considering whether QinQ or 802.1q tunneling is right for them. This technique solves the transparency problems for enterprises and enables service providers to offer the desired Layer 2 services at the same time. However, because of some of the issues described in this chapter, QinQ might not work for everyone. |