Overview

The term bridged describes routed IP data delivery. Each router along the bridged path decides where to send data, in order for data to traverse a number of routers. Bridged connections provide IP connectivity to the client's premises over an internet grade Broadband internet link. Each part of the network between your premises and Westnet's network is statically configured. Traditionally this has been regarded as more simple, due to the simplified configuration required at the premises (configuration is approximately the same as networking two computers). However the provisioning, configuration and fault resolution processes for supporting this method of internet connection are often lengthy.

Layer 2 service simulates a dialup service over a phone call, by providing a point-to-point tunnel between your premises and Westnet's network. This configuration is quite dynamic and requires only the correct operation of Westnet's entire Broadband network, and the correct configuration of your Broadband connection at the telephone exchange. An entire network can then be created to locate a path for your internet connection to Westnet. Westnet is able to provide for redundancy at the end of this connection in ways not possible using bridged services. However, there is one significant difference - once the tunnel between you and Westnet is established, anything that goes into that tunnel emerges out of the other end at Westnet. This means that routing decisions must only be made within our wholesale providers network on the basis of locating Westnet, not on the basis of the location of each Westnet customer. This simplicity allows a degree of redundancy and flexibility not possible on bridged services.

Please note: A bridged connection is a 'routed' connection. A Layer 2 connection is a 'tunnelled' or PPPoE connection.

Why Westnet has Discontinued Offering Layer 3 (Bridged) Services

Over the last 3 years, Westnet has experienced a considerable decline in the demand for bridged Broadband services. Due to the requirements needed to support bridged services (i.e. manual ordering processes, complex manual configurations, higher than normal lead times for configuration changes, etc) bridged services also represent a disproportionate use of resources such as training, automation, network engineering and network resources.

The issue has been examined extensively and is regarded as essential to ensuring that Westnet continues to provide a high level of service to our customers across our range of products.

Existing Layer 3 (bridged) Customers Wishing to Migrate to Layer 2 (Tunnelled)

New Layer 3 connections and reconnections of existing services will not be available from January 1st 2006 onwards. Changes to continued bridged services (such as IP address changes, speed changes etc) will be available at a fee of $55.00 per instance.

Free migration from a Layer 3 service to a Layer 2 service will be offered from May 29th to June 30th 2006. As of July 1st 2006, migration will cost $55.00.

If you wish to migrate your existing Layer 3 service to Layer 2, please contact the Westnet Provisioning Team on 1300 887 387.

Advantages of a Layer 2 (Tunnelled) Service

• A Layer 2 account is secured by a password.
• Shaping is available to protect against excess data charges.
• Lite Broadband plans are available for low cost / low usage accounts.
• Automatic configuration of certain features such as [Access Control] and DNS are available.
• Accounts are portable and not confined to a single location, allowing a greatly simplified relocation. Westnet can simply connect a new service and move the username / password to the new location when you're ready.
• The same (or static) IP addresses are generally available over backup dialup services.
• Configuration changes can often be made internally by Westnet, eliminating a 3-5 day lead time for fault resolution on bridged technical issues.
• Network infrastructure is more redundant and reconfigurable, allowing Westnet to reconfigure its network to avoid prolonged service disruption in the event that a change is required.
• The visibility of Layer 2 services allows historical data regarding the quality and reliability of your connection to be recorded, providing valuable real-time information in the event that a problem occurs.

Advantages of a Layer 3 (Bridged) Service

• There are slightly less transmission overheads on bridged services (0.02% on a 1500 byte packet) meaning that customers can see a small but noticeable increase on performance.
• The configuration required at the customer end is reduced and in some instances allows older, less flexible equipment to be used.

Disadvantages of a Layer 2 (Tunnelled) Service

• A small interruption of 60 seconds can interrupt the tunnel / session for your internet connection.
• Establishing a tunnel requires authentication which typically takes about 1 second.
• If a network element fails and recovers, bridged services simply begin working once again. Layer 2 services must re-check their password. Historically this has meant that a large number of people perform this re-connection at the same time and this can prove challenging for authentication servers.

Disadvantages of a Layer 3 (Bridged) Service

• Changes to a bridged service generally take 3-5 working days and involve a fee resulting from the use of external administrative requirements.
• Relocating a bridged service without significant interruption is impossible, if it is required to keep the same IP addresses. As the addresses form part of the configuration of the Broadband service it is not physically possible to permit the same addresses in different locations.
• No diagnostic information is available. In the event that bridged services encounter a problem, it will likely go through a lengthy fault resolution process involving external parties, as to whether a configuration change is required or not. This results in problems (that could potentially be resolved in minutes with the right information to hand) possibly taking days to reach a similar conclusion.
• Bridged services are a very inefficient use of IP address space, utilising a minimum of 4 addresses in order to provide a single address at your premises. Whilst this does not represent a technical challenge or particular cost, IP address space (IPV4) has a limited number of addresses available globally and conservation measures are essential in maintaining the growth and scalability of the entire internet. This conservation is a stated goal of the APNIC, which is responsible for usage of address space in the Asia-Pacific region.
• Small interruptions in any dependant network affect all Broadband services. However bridged services do not have any accounting facility and therefore the reliability of a bridged service is unknown. In comparison, a Layer 2 service could be demonstrated to have continued network connection for the length of each single session (can be weeks or months) and it is possible to identify when and for how long interruptions occur, even if they have no perceived impact.

Reasons Why You Might Need to Maintain a Layer 3 (Bridged) Service

Some older Broadband equipment may not support a PPP type connection in certain circumstances. Firewalls and routers that are used to control an internet connection will need to be capable of performing PPP connection negotiation. It is extremely unlikely that your equipment will not support PPPoE (which is required for a Layer 2 service).

Service Level Agreements on Layer 2 (Tunnelled) or Layer 3 (Bridged) Services

The bridged products offered by Westnet are provided over the same infrastructure and operated with the same efficiency. Each type of Broadband service has traditionally been available from Westnet at the same price. Neither has ever been provided by Westnet with a Service Level Agreement.

A Service Level Agreement occurs where a product is offered with guarantees and penalties.

Additional Address Space on Layer 2 Connections

One of the leading reasons for providing a bridged service up to early 2003 was the ability to provide more than one reachable internet address over the same internet connection. At that time, tunnel-based internet connections with this capability were not available. Though this is a rare requirement (typically used by customers who use their internet connection to provide services on the internet (such as Web, Mail, DNS) or for services located at a business premises) there does exist a need to continue providing additional address space.

Since 2003, it has been possible to provide additional address space over Layer 2 (or tunnelled) internet connections. Configuring address space over bridged connections can take up to 5 working days. Layer 2 connections provide us with the ability to perform this configuration almost immediately, in addition to adding and changing configurations very promptly. So in this respect, Layer 2 actually offers a better, more reliable and more flexible method of allowing the use of additional address space.

Outages

The most common reason for choosing bridged products is a belief that it represents a 'more reliable' Internet Grade connection. This belief commonly stems from outages experienced during the early days of tunnel-based internet connection. In examining the kind of interruptions that an ISP of today is likely to suffer, there are far few network failures that impact on Layer 2 services that do not impact bridged services. However, Layer 2 services provide excellent visibility of any interruption of service, whereas bridged services do not. Customers with Layer 2 connections are able to see easily where they have had uninterrupted connectivity for periods exceeding two months. Any interruption longer than 60 seconds is recorded by Westnet. In comparison, bridged services provide no such visibility and while proponents of bridged services argue that tunnel-based connections can reconnect as often as each week, it is not possible to determine how often a bridged service is interrupted, even though it uses the same infrastructure.