Why Comcast is Installing Direct Fiber for Gigabirt Pro Services

There is a good reason Comcast is making symmetrical 2 Gbps fiber-based Internet access available across much of its footprint, described as reaching 18 million homes, or about 85 percent of its current network footprint.

For consumer customers, the Gigabit Pro service allows higher bandwidth than the 1 Gbps standard Comcast now is preparing to offer all consumers.

But 2 Gbps symmetrical, provided over a direct fiber to home connection, will be more important for business customers.  

Chris McReynolds, Level 3 VP, says Level 3 does not consider Ethernet-over-HFC service to be competitive with the business Ethernet services that Level 3 sells to business customers.

Jitter is the problem. Jitter levels associated with Ethernet-over-HFC are too high, compared to telco fiber or copper access, he says.

But maximum transmission unit (MTU) performance of cable hybrid fiber coax access networks also is an issue.  

MTU is a key performance standard for Ethernet because it has a significant effect on the rate and efficiency of throughput.

The higher the MTU, the higher the rate of throughput. Ethernet-over-HFC delivers an MTU of 1518 bytes (1522 bytes with a single virtual LAN tag), he says. “This is significantly below the MTU that can be supported by Ethernet-over-fiber and Ethernet-over-legacy loop networks, which are increasingly supporting MTUs far above 2,000 bytes,” says McReynolds.

Also, he says, cable Ethernet access often is restricted to 10 Mbps.

Of course, all those issues will undoubtedly be resolved when Comcast adds Gigabit Pro access over dedicated fiber lines.