Interesting article.
-Jay
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Bay Switch Right on Target
High-density Accelar 1200 blows away the competition
By Pankaj Chowdhry, PC Week
February 9, 1998
Review
In the struggle to control congested networks run amok, administrators are already armed with switches that serve as knives and hatchets to clear the way. Bay Networks Inc. just gave them a bulldozer.
Although other vendors are still just promising high-density Layer 3 Gigabit Ethernet switches with advanced features, Bay Networks has delivered one in the Accelar 1200. Able to accommodate 96 Fast Ethernet ports or 12 Gigabit Ethernet ports, the switch has extensive management capabilities, a scalable design and a modular chassis.
With breakneck performance in PC Week Labs' tests, the Accelar soundly trounced its only real competitor, Cisco Systems Inc.'s 134-port Catalyst 5500 equipped with an RSM (Route Switch Module), and earned an Analyst's Choice designation.
Most Gigabit Ethernet products are quite immature. For example, the CoreBuilder 3500 that 3Com Corp. shipped late last year is fast as lightning but lacks support for the OSPF (Open Shortest Path First) routing protocol, QOS (quality of service) and RMON. The Accelar 1200 not only supports these features but also makes them easy to use. (For PC Week Labs' review of CoreBuilder, see PC Week, Dec. 22/29, 1997, Page 77.)
Priced at $75,000 fully loaded with 96 Fast Ethernet ports, the Accelar 1200 chassis shipped last month. The Gigabit Ethernet modules began shipping this month: The two-port module we tested is $10,250.
The Accelar 1200 is the first Layer 3 Gigabit Ethernet switch Bay has shipped that's based on technology it acquired by purchasing Gigabit Ethernet startup Rapid City Communications Inc. last summer.
The Accelar 1200 management application, matter-of-factly named Device Manager, provides easy access to all of the switch's advanced features. From this graphical interface we were able to configure OSPF routing, RMON and VLANs (virtual LANs). However, the switch lacks support for a DHCP helper, which most routers have.
Unlike competing products, management wasn't an afterthought in the Accelar 1200--it has every option an IS manager needs. In addition to Device Manager, the switch has a command line interface and an embedded Web server. The latter let us configure the switch's parameters from any Web browser.
Device Manager lacks a few niceties, however. For instance, we could not view the ARP (Address Resolution Protocol) tables with Device Manager; instead we had to drop back to the command line and run out a list of the table entries in a terminal program.
On every other Layer 3 switch we have tested, to enable routing we first had to configure a VLAN and then assign an IP address to allow the ports to route traffic. This works fine for situations where several ports are routing traffic over the same subnet, but is more expensive than using switching ports.
It's more efficient to simply assign an IP address to one port and use it as the gateway. Although neither way is wrong, Bay's Accelar 1200 switch gives administrators more flexibility by supporting both methods.
All of these management capabilities are important, but they would be almost useless if the switch were to fail. Bay goes to great lengths to make sure that this doesn't happen.
The Accelar 1200 is equipped with two redundant power supplies, can be outfitted with redundant switch processors and has an interesting proprietary feature called LinkSafe, which is implemented on the switch's Gigabit Ethernet modules.
LinkSafe enables gigabit-link failover by providing two fiber ports for a single Gigabit Ethernet port. A cable can be attached to each fiber port, and the two cables can be routed through different parts of a building to another Accelar 1200 switch. If one of the cables is cut, data traveling between the switches is immediately transferred to the other cable, which allows for construction of a highly resilient backbone.
A solid foundation
At the heart of the Accelar 1200 is an innovative shared-memory architecture that replaces the archaic crossbar architecture used in many other switches. This shared-memory architecture allows the 1200 to scale very well, because it is not hampered by the limitations of a constrained backplane, especially the head-of-line blocking problems often associated with a crossbar architecture.
More important, this scalability protects the investment of those who purchase the 1200, because the individual modules, which accommodate only 16 Fast Ethernet ports, can be replaced with higher-density modules.
The Accelar supports six media modules and two switching modules. The maximum 96-port configuration cannot max out the processing power of even a single switching module, leaving a lot of room to grow.
For the Accelar to graduate to a higher port density, Bay will have to increase the bus speed on the switch from its limit of 2.4G bps per module.
The current limit means that the two-port Gigabit modules, if running full out, in full duplex, can oversubscribe the bus.
As a partial remedy to this problem, Bay offers a dual-prioritization scheme, which allows high-priority traffic to be processed ahead of low-priority traffic. It is a shame that the company does not offer any policy-based networking features for the Accelar 1200, because its shared-memory architecture would adapt well to that application.
Shootout at the switch corral
Competition for the Accelar 1200 is slim. Most other Layer 3 switches on the market do not have the port densities of the 1200, with the exception of Cisco's Catalyst 5500 equipped with RSMs, which can support as many as 134 Fast Ethernet ports.
To test the two systems, we attached them to Netcom Systems' SmartBits 1000 traffic generator. Using the Smart Applications software, we tested the maximum Layer 3 forwarding rate the switches could achieve without packet loss. Handling from one Fast Ethernet stream up to eight, the Accelar switch never dropped a packet. The Cisco RSM didn't fare as well, dropping 73 percent of the packets when running eight 100M-bps streams.
We used only IP traffic in these tests because the Accelar 1200 routes only IP traffic. This is in stark contrast to the Cisco RSM, which can route almost every protocol on the planet, including Novell Inc.'s IPX.
Because most of the growth on enterprise networks is IP traffic, however, the Accelar switch's limitation shouldn't present much of a problem.
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PC Week Labs Executive Summary: Accelar 1200
Bay Networks' Accelar 1200 sets the standard for Layer 3 Gigabit Ethernet switches. With support for a host of advanced features and 96 switched Fast Ethernet ports or 12 Gigabit Ethernet ports, it deserves serious consideration for handling congestion in any large network core.
USABILITY A
CAPABILITY A
PERFORMANCE A
INTEROPERABILITY B
MANAGEABILITY A
Pros: Blazingly fast performance; high port density; extensive management capabilities; scalable, modular, architecture.
Cons: No support for policy-based networking; no DHCP helper; no support for Novell's IPX protocol.
Bay Networks Inc., Santa Clara, Calif. (800) 622-9638; www.baynetworks.com
Scoring methodology: www.pcweek.com/reviews/meth.html
The Device Manager app clearly pictures the Accelar 1200's activities. |
