Information Technology Reference
In-Depth Information
IPsec Virtual Tunnel Interface Design
Virtual tunnel interface (VTI) is a new IPsec VPN design option available in Cisco IOS
software. VTI has some interesting advantages over previous IPsec design options, includ-
ing support for dynamic routing protocols and IP multicast without using GRE or mGRE
type interfaces. Also, because VTI tunnels are assigned an unique interface, specific tun-
nel level features such as QoS can be configured for each tunnel separate from other VTI
tunnels. The physical topology for VTI designs can be designed the same way as IPsec di-
rect encapsulation using multiple headends and two tunnels from the remote sites, one to
each headend.
Layer 2 Tunneling Protocol Version 3
L2TPv3 provides a high-speed transparent Layer 2 to Layer 2 service over an IP backbone.
The signaling in L2TPv3 is responsible for the control plane functions such as authentica-
tion, session IDs, and the exchange of configuration parameters. L2TPv3 has support for
Frame Relay, Ethernet, IEEE 802.1Q, HDLC, and PPP encapsulation types to be tunneled.
Service Provider Managed Offerings
Metro Ethernet
Demand for bandwidth in the metro-area network (MAN) is increasing due to the result
of the high throughput requirements of data-intensive applications. Today, many SPs are
offering Metro Ethernet services to fulfill the demand; these are based on Ethernet, IP,
and optical technologies such as dense wavelength-division multiplexing (DWDM) or
coarse wavelength-division multiplexing.
Metro Ethernet services can provide more bandwidth, the ability to upgrade the band-
width as needed, and higher levels of redundancy through multiple route processors. Be-
cause Metro Ethernet can support the higher bandwidth requirements, it is often better
suited to support converged network services (for example, voice, video, and data services
combined on the same link).
Most service providers are using Ethernet as a method to access their backbone network.
Ethernet handoff is becoming common even if the transport is based on SONET/SDH,
MPLS, Frame Relay, or the Internet.
Ta ble 7- 2 shows the benefits Ethernet handoffs at the customer edge provide.
Ta b l e 7- 2
Benefits of Ethernet Handoffs at the Customer Edge
Benefit
Description
Service-enabling solution
Layering value added services in addition to the network
Flexible architecture
No need for truck roll for increasing port speeds
No need for new customer premises equipment (CPE)
Evolving existing Frame/ATM services to an IP-based
solution
