The idea is to maintain the low cost of Ethernet while adding enough Sonet functionality to ensure compatibility. This is possible because 10 Gigabit Ethernet's speed is so close to OC-192 Sonet's 9.953 Gbps. The WAN PHY adapts to that speed and adds some Sonet framing, though it does not implement all Sonet's features and is not meant to replace Sonet. For example, 10 Gig does not implement Sonet clocking and cannot participate directly in a Sonet ring. The bottom line, however, is that an ISP, carrier or very large enterprise may be able to use 10 Gig technology to cut costs.
Another IEEE working group, 803.17, is developing ways to extend Ethernet's reach across the WAN and directly address the inefficiencies of Sonet. The RPR (Resilient Packet Ring; www.rpralliance.com) protocol is designed to achieve the sub-50-microsecond failover of Sonet rings while maintaining the benefits of packet-based Ethernet, such as low cost, ease of deployment and efficient use of circuits. The group is scheduled to ratify the standard in 2003.
The Metro Ethernet Forum is also working on ways to bring some of the benefits of Ethernet to the MAN and WAN. We hope this will translate to cheaper high-speed WAN and MAN connectivity.
Still Some Flies In the Jell-o
The IEEE 802.3ae standard is all about interoperability. If you use one vendor's equipment on the backbone and another's in the closet, they should work together. The 10 Gigabit Ethernet Alliance has been demonstrating multivendor interoperability at trade shows for the past year, and many vendors have been participating, so there is an excellent chance that products you buy today will be interoperable. Still, it's early enough that you may want to get that in writing from your vendor. Also, some vendors' chassis-based cards will connect to the backplane at only 8 Gbps. This may be tolerable, but make sure you know what you're getting.
As for troubleshooting your 10 Gigabit Ethernet connections, you won't be able to buy a protocol analyzer soon--the vendors we spoke to said they have no plans to introduce these testers. If you have to monitor connections, you'll have to do it on the edges of your network, where there are slower connections. Another option is to use a span port off a gigabit interface on the backbone router or switch. You'll be able to do this if you can limit the 10 Gigabit traffic to less than 1 Gbps while you are monitoring.
People Who Need Bandwidth
So, should you buy 10 Gigabit Ethernet products now? For some technologies--SANs using iSCSI, for example--10 Gigabit's low latency and high speed will be a boon. Certainly, any application that moves around lots of data will benefit. However, the most obvious place to install 10 Gigabit will be the backbone. Look at the utilization of existing Gigabit Ethernet connections using SNMP-based network management or gigabit analyzers. Given 10 Gigabit Ethernet's high entry prices, the last thing you want to do is blindly assume that you need it because you've had some complaints of slow response times. If your utilization is hitting 100 percent spikes--or is heading in that direction--you have a case, though you might be better off trunking Gigabit Ethernet connections together for now and waiting for 802.3ae products to mature and prices to come down. But if you are running out of fiber to accomplish trunking, and leasing or adding more fiber will be very expensive, then the cost is easy to justify.
Most of us don't need 10 gigabits' worth of Ethernet today, but those who do will be greatly relieved. And those who don't need it now will someday. Keep in mind that there will probably be even faster versions of Ethernet in the future. While those who will be working on that goal are probably taking a well deserved rest after completing 802.3ae, speeds of 40 or 100 Gbps have been bandied about. Bob Metcalfe should be proud.
Peter Morrissey is a full-time faculty member of Syracuse University's School of Information Studies, and a contributing editor for Network Computing. Send your comments on this column to him at ppmorris@syr.edu.
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