|
Networks & Infrastructure
Carrier Ethernet searches for direction
Availability and customer education are keys to growth
by Doug Allen
Carrier Ethernet Services is arguably the hottest sector for telcos these
days. New switched metro and long-haul Virtual Private Line Services
(VPLS) services from Verizon Business and AT&T are the latest indication
that next-gen Ethernet services are here, and are poised for rapid
growth.
But the industry remains constrained by a number of factors,
not the least of which is market awareness. Even with simple service
definitions from the Metro Ethernet Forum (MEF) to fall back on, many
potential customers are still having a tough time sorting out all the
flavors to choose from, and where to deploy them. David Hold, a senior
analyst in Business Network Services at Current Analysis, sat down
recently with Telecommunications’ Senior Editor Doug Allen to talk about
carrier offerings and their applications.
Telecommunications: What are the primary Ethernet services carriers are
offering business customers, and how are they targeting them at
different types of business (i.e., small-to-medium-business or
enterprise)?
Hold: In terms of general topology, carrier Ethernet services can be
divided up into three main categories: Connecting a single building or
data center to another (point-to-point); connecting a single building to
a cloud type service like the Internet or Private IP VPN services
(access), and connecting one or more locations to each other
(multipoint). Most Ethernet today is metro area point-to-point.
Switched multipoint services, formerly known as Transparent LAN, have
been almost exclusively deployed in the metro area, although the new
VPLS services are both metro and long-haul, and will soon go
international.
Traditionally, Ethernet required fiber to the premises, which limited it to
high bandwidth applications for medium to large enterprises. A typical
example is connecting data centers at gigabit rates. Another would be
connecting regional medical center facilities for high bandwidth medical
imaging and off-site storage applications. However, with the advent of
Ethernet over copper solutions, branch offices are now candidates for
Ethernet access up to about 10Mbps.
On the access side, Ethernet is a promising alternative to TDM for local
access circuits. Check out Verizon Business’ Ethernet-based Converged
Packet Access service, which is designed to combine multiple access
types over a single Ethernet connection.
Telecommunications: How do you segment the market? Do you
distinguish between types of services—by application, by transport layer
(Layer 2/Layer), SONET or WDM used, speed, dedicated vs. shared, long-
haul vs. switched intra-metro, etc.?
Hold: All of the above, depending on the situation. Ethernet is most
commonly classified by transport type—at the physical/optical layer it is
native fiber, SONET/SDH (more expensive), DWDM (high bandwidth but
unprotected) and copper (SHDSL or NxT1); and at L2/L3 it used to be
transported over ATM and still is in some places. Today, Ethernet is
increasingly running over MPLS in the case of Virtual Private Wire
Services (point-point pseudowires) or VPLS (multipoint pseudowire mesh).
By geography, you can also easily segment services by metro, wide area
inter-city and cross-border/international.
Telecommunications: What kinds of important QoS and security
parameters are carriers including with these services? Other attractive
incentives could include service and/or applications bundles or special
pricing incentives.
Hold: This is an area for further development and exploration. There has
been little QoS in traditional Ethernet services, although some services
use VLAN tags to separate traffic for prioritization; VPLS services can
make use of VLAN tags, and can also support QoS the same as in MPLS
using DiffServ codepoint (DSCP) or IP Precedence bit marketing.
Telecommunications: Strategically, where are providers trying to go in
terms of business models and service deployment/ technology
development (maybe inter-city switched Ethernet service)?
Hold: Ethernet is evolving from its roots as mainly a lower cost interface
to a metro-optical transport service, to an any-to-any switched data
service on a par with frame, ATM or IP/MPLS-VPN. As a Layer 2 VPN,
Ethernet still has a ways to go to be fully competitive with IP/MPLS
services, mainly in terms of scalability in large networks, but it can be an
attractive migration alternative from legacy frame/ATM or TDM services
for those end-user organizations that are unwilling to turn control of IP
routing over to a carrier.
Telecommunications: When you evaluate carriers’ business models and
service deployment plans discussed in question four above, from a
customer perspective, what are the likely implications for customers six
to twelve months out if carriers follow through on their plans? How will
they impact customer’s network usage patterns and buying habits
further out?
Hold: It has been interesting to watch AT&T and Verizon Business as
they deploy Ethernet Access and VPLS services. The two carriers tend
to mirror each other, with one pulling ahead and the other playing catch
up. Some of AT&T’s largest customers have been demanding VPLS for
several years, and some have defected to alternative carriers over that
issue. In the end, the customers are begging their service providers to
offer more than just IP-based services, so there is clearly a role for wide
area networking services at Layer 2 beyond frame relay and ATM.
Telecommunications: What are business customers’ primary concerns
when adopting carrier Ethernet services and how do you see carriers
today and in the future addressing them? Where are they getting the
most pushback or having the most real-world trouble developing
adequate solutions for these concerns?
Hold: I would say that [the first concern] is getting it in the first place,
because availability of fiber can be spotty, especially outside of
downtown urban cores, and fiber extension can incur sizable costs and
lengthy delays.
[The second issue] is the fact that there are so many different types of
services that go under the name Ethernet that it can be confusing to
know exactly what you are buying if you are not a networking expert. If
you think about frame relay, which was the most successful wide area
network service since T1, you did not have to worry about distance
charges for example, except for the access circuit, and it ran over T1 so
you could get it just about anywhere.
[The third issue] is scalability for wide area multipoint networking
services such as VPLS. Many experts recommend keeping the numbers
of end-points connected to a VPLS in multiples of a few dozen, which
poses challenges for 1000 site networks. Beyond that, you may have to
segment the network with routers, which is do-able, but in some ways
that can defeat the purpose trying to build a pure Layer 2 VPN.
Hierarchical VPLS services could help, but are not yet in commercial
deployment. Scalability of VPLS to large networks, in my opinion, is an
issue that has not yet been adequately addressed by the carriers.
|
