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Open Access - Connectivity Management
Manages connections with open access for broadband services
By: Bruce Bahlmann - Contributing Author (your
feedback
is important to us!)
Created: October
26, 2000
This article is
the second article in a 5 part series on open access. This series includes: Overview, Connectivity Management, Service Management, HFC Management, and Transparency.
Offering open access is not just a matter of opening up one’s
Internet service to two or more Internet Service Providers (ISP). It’s a system
designed from the ground up that provides broadband customers with a choice. The extent of
choices provided to broadband customers and the transparency associated with the selection
process will differentiate various open access solutions. One of the keys to providing a
versatile open access system is successfully navigating the management of
connectivity.
Connectivity management is one of three key areas of open access as
described in last month’s article on open access. The other key areas are Service
Management and Hybrid Fiber Coax (HFC) Management. Next month’s article will focus on
Service Management.
Connectivity management provides the foundation for open access. It
is the underlying networking and provisioning scheme that gives multiple ISPs access to
all broadband customers. By providing ISPs with access to broadband customers,
connectivity management allows these ISPs to configure broadband customers with
information specific to their Internet service. This information is unique to each ISP and
can very well differentiate one from another in terms of speed, availability, and
capability. As a result, each ISP must be able to provide broadband customers with their
own IP addresses, Domain Name Servers (DNS), email servers, etc. and connectivity
management makes all this possible.
Connectivity management is also responsible for providing broadband
customers with much needed transparency among ISPs. Transparency minimizes (or eliminates)
the need for broadband customers to perform additional configuration upon changing their
current ISP. This allows a broadband customer to change ISPs without needing to
reconfigure various Internet applications running on their Customer Premise Equipment
(CPE).
To achieve management over connectivity several things must be
considered. The first is opening access to the HFC. This enables ISPs to reach out to
broadband customers and make them part of their service. Secondly, the broadband customer
must be given information to access various components of their service described above
(i.e. DNS, email, news, etc.). Lastly, it must be convenient for the broadband customer to
change ISPs. Like changing long distance phone companies, changing ISPs must be completely
transparent to the user. Let’s take a closer look at the things we must
consider:
Opening Access to HFC
There are several ways that
open access could facilitate multiple ISPs to access broadband’s HFC. One way would
be to create multiple radio frequency (RF) local area networks (LANs) off each HFC node as
shown in Figure 1. An RF LAN consists of a network that is created as a result of a Cable
Modem Termination System (CMTS) utilizing a pair of frequencies (one for transmit and one
for receive) on the HFC. The RF LAN provides an environment that allows one or more cable
modems (CM)s along an HFC segment to utilize the frequency pair to form a LAN. However,
since this is not a traditional LAN connected via fiber or category 5 wire but rather by
HFC (more specifically two frequencies within the HFC), it is being referred to as an RF
LAN. In a multiple RF LAN HFC, there would be 2 or more independent RF LANs each using
their own unique frequency pair (e.g. two RF LANs would require four HFC frequencies).
This method would be resource intensive, as it would require separate CMTS gear (or
blades) for each Internet service provider (ISP) as well as require additional frequency
pairs for each ISP on the HFC. Since headend, rack, and frequency spectrum space are all
extremely tight this method of facilitating open access has not received much attention.
However, from purely an operations standpoint it is the cleanest way of providing total
separation among open access choices. This separation comes out of the fact that once the
broadband customer selects which ISP they want, their CM can be provisioned to join that
ISP’s designated RF LAN. This action pulls anything behind the CM along with it (i.e.
the CPE is forced to join the CM’s RF LAN). Once on the new RF LAN the traffic,
provisioning, etc. among ISPs are totally isolated from one another on the most critical
portion of the transport (the HFC). This prevents traffic from one ISP from impacting
other ISPs.
Figure 1 Multiple RF LAN w/
Single ISP Network Presence
Another way to provide
multiple ISP access to broadband’s HFC is to give each ISP a network presence on each
RF LAN as shown in Figure 2. Network presence permits CPEs to obtain IP addresses from
their selected ISP. This method utilizes a single RF LAN that has been populated with a
network presence associated with each ISP. Upon activation, the CPE will select which ISP
it wants and be provisioned with an IP address from that ISP. The IP address it is
provisioned with will be one of a pool of IP addresses that the ISP has allocated to that
RF LAN. Essentially, each ISP will provision a small pool of their IP addresses to each
and every RF LAN. These pools of addresses provide each ISP with a network presence on the
RF LAN. When that ISP is selected by a CPE it will be provisioned to that ISP and receive
an IP from that ISP’s address pools where ever it plugs into the HFC. This method is
the easiest to implement but suffers from various operational challenges as it grows or is
deployed in very large cable systems. For example, all ISPs share the same RF LAN, meaning
that traffic from one ISP can affect that of another ISP. There are also challenges with
regard to managing IP address space across ISPs. Efforts to manage IP addresses must
ensure that when a new broadband customer selects an ISP there will be an IP address
available from that ISP on the broadband customer’s RF LAN. As a result, each ISP
would need to continually balance their need to conserve IP addresses with their need to
provide opportunities for new broadband customers to join their service.
Figure 2 Single RF LAN w/
Multiple ISP Network Presence
Configuring CPEs for ISP Applications
Once a CPE has been provisioned with an IP address from the broadband
customer’s desired ISP, it is now ready to be configured for that ISP’s
applications. ISP applications include email, news, DNS, web hosting, etc. These
configurations can be applied manually or automatically depending on the ISP and the
application. For example, DNS can be configured automatically alongside the IP address
during provisioning whereas the news server must be manually configured. These
configurations can also take on two different forms: IP address or hostname. An IP address
configuration merely consists of an IP address (e.g. 24.128.44.6). A hostname (e.g.
news.mn.mediaone.net) configuration consists of a pointer to an IP address. While both of
these configurations could potentially have the same result, they are vastly different
operationally. For example, using a hostname instead of an IP address is easier to
maintain, as this information can remain constant even if the IP address it is pointed to
changes. However, an IP address must remain constant, because a change in this information
would require all CPEs with this information to be changed – a major undertaking if
the information is manually configured.
Once configuration has been completed, the broadband customer is
fully operational. At least until they change their mind and would like to switch ISPs.
When this occurs, they must re-establish connectivity with the new ISP and configure their
CPE applications to work with the new ISP. The inconvenience this creates for the
broadband customer alone will reduce the frequency of ISP changes. Thus, there must be
transparency among ISPs.
Making ISPs Transparent
Although each ISP is different, they provide many of the same things
– Internet access along with similar applications that use the Internet (such as
email, news, web hosting, etc.). These similar applications allow standards-based
application clients to run on the broadband customer’s CPE. So, even though ISPs may
run different vendor applications, because these applications are standards-based the
broadband customer merely needs to configure their CPE to use them. While some CPE vendors
have made the task of changing configurations easy (by providing a single interface for
changing common Internet configurations), it is still necessary for the broadband customer
to manually configure their CPE after changing ISPs.
Another problem with manual configuration changes is that it
complicates open access evolving from a choice ISPs for all services to an à la carte
type of offering. An à la carte offering would permit a mixture of ISP services as well
as 3rd party service providers to be bundled together to produce a complete
Internet service for the broadband customer. However, this bundling may be confusing to
the broadband customer – since nearly any type of change would require additional
manual configuration of the CPE by the broadband customer.
Changing ISPs may also impact certain externally important contact
information about the broadband customer. For example, if the broadband customer changes
the ISP that provides their email, their email address would change. This can be damaging
as everyone that the broadband customer had previously shared his or her email address
with now has the wrong information. Similarly, a broadband customer’s personal web or
voice over IP service site may also be impacted by the change of the ISP who provides this
service.
By providing transparency, the broadband operator looks out for the
best interest of their customers. Transparency supplies the broadband customer with an
address for email, web hosting, and voice over IP that does not change regardless of which
ISP or 3rd party service provider actually provides the service. It also
provides the broadband operator with an opportunity for it to brand the service in their
company name as opposed to the broadband customers current ISP selection. As a result, all
their customers will have personal web pages and email addresses with their company name
(i.e. bahlmann@mediaone.net or www.mediaone.net/people/~bahlmann)
and this will not change no matter which ISP currently handles this functionality for the
broadband customer.
Connectivity management must offer inviting opportunities to attract
service providers who are new to broadband. These service providers would then compete
with existing ISPs and service providers for broadband customers. Connectivity management
must also make joining existing service providers and ISPs simple and painless. Lastly,
connectivity management must emphasize transparency for broadband customers so when they
make changes the only thing they need to change is the amount of money they save each
month for the service.
Summary
Connectivity management provides the foundation for an open access
offering. It supplies broadband customer CPEs with the critical information they need to
access the Internet while providing the broadband customer with a choice of ISPs and 3rd
party service providers. Connectivity management also ensures that the ability of a
broadband customer to choose (or change) ISPs is not tarnished by requiring numerous
manual configurations.
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