networkZONE Products for the week of May 13, 2002
The StrataXGS chip family combines the field-proven, multi-layer switching capabilities of Broadcom's StrataSwitch technology with wire-speed Gigabit and 10-Gigabit Ethernet switching performance. StrataXGS, in combination with Broadcom's Quad Gigabit Ethernet copper transceivers, enables system vendors, for the first time, to build 12-, 24- and 48-port multi-layer Gigabit Ethernet stackable switches, supporting systems with up to 384 GbE ports, at a cost structure comparable to that of today's Fast Ethernet switches. Gigabit switches based on StrataXGS will drive down the cost of delivering intelligent bandwidth at Gigabit speeds (1000 Megabits per second), scanning millions of packets containing voice, video and data, and prioritizing each of those packets for maximum efficiency and quality of service.
The StrataXGS architecture reduces the number of components in a typical GbE switch by up to 90 percent. The unique integration of high speed SerDes I/O and packet buffer memory allows customers for the first time to build a 24-port Gigabit Ethernet switch using only 2 chips, and a 48-port Gigabit Ethernet switch using only 5 chips, in each case, independent of the CPU subsystem. This reduction in component cost coupled with StrataXGS's efficient architecture decreases system assembly time, board space and power, enabling manufacturers to offer customers a multi-layer, scalable Gigabit Ethernet switch solution at below $100 per port.
Broadcom's StrataXGS family features on-chip SerDes I/O operating at 3.125 Gigabits per second (Gbps), enabling very high-speed chip-to-chip, board-to-board and box-to-box interconnections. Additionally, SerDes cores operating at 1.25 Gbps are integrated into every Gigabit port, eliminating the need for external transceivers when connecting to fiber modules. In addition, the integration of this SerDes core into each Gigabit port provides the most pin efficient interface (SGMII) when connecting to Gigabit copper transceivers. The integration of this high-speed I/O technology minimizes chip count, simplifies board design, and reduces overall system cost.
Broadcom's StrataSwitch II family is the most widely deployed merchant silicon in multi-layer Fast Ethernet and Gigabit Ethernet enterprise switches today, shipping in millions of ports per quarter in products from all of the major enterprise network switch vendors. By building upon the StrataSwitch II architecture in StrataXGS, Broadcom enables customers to reuse their existing software base, further reducing the cost and time of migrating to multi-layer Gigabit Ethernet switches.
"The integration and performance breakthrough we've achieved in StrataXGS raises the bar that was set by our highly popular StrataSwitch line," said Marty Colombatto, Vice President and General Manager of Broadcom's Networking Business Unit. "StrataXGS, coupled with our Broadcom NetXtreme controller technology for desktop computers and servers, provides corporate enterprise IT managers with the most cost-effective migration path to Gigabit Ethernet."
"The adoption of Gigabit Ethernet connectivity to servers and increasingly more PCs will continue to fuel the need for multi-port desktop switch designs in the near future," said Sean Lavey, an analyst at IDC. "The availability of advanced switch chipset products, such as Broadcom's StrataXGS, that deliver lower bill-of-material costs and wire-speed Gigabit performance, will continue to accelerate this speed's migration making it one of the hottest growth segments in the networking semiconductor market."
StrataXGS Architecture
The initial members of Broadcom StrataXGS family are two Gigabit Ethernet switches and two high-speed fabric chips, giving manufacturers a building-block system solution that can support standalone switches, multi-layer stackable switches, modular chassis switches, and server switches. The chips are built in an advanced 0.13-micron CMOS process technology with copper interconnects to achieve the lowest power, maximum performance, and highest integration level. Future members of the StrataXGS chip family will include products for 10/100 Ethernet and 10-Gigabit Ethernet connectivity.
Advanced features of the StrataXGS architecture include:
Product Information
Members of the new StrataXGS chip family include the:
Reference Designs and Software Support
To reduce system design time and accelerate customer time to market with
StrataXGS, Broadcom offers a range of fixed 12-, 24-, and 48-port switch
reference designs and stackable 24- and 48-port reference designs, plus
a complete modular chassis reference design with up to 192 Gigabit Ethernet
ports. The reference designs come with comprehensive design information,
including schematics and layout files, and are fully functional switches
with the Broadcom switch API source code.
analogZONE Says . . .
Worthy Adversaries - Broadcom's StrataXGS Gigabit Ethernet Switch Chips Come Gunning For Marvell
Since I have successfully avoided Las Vegas for the past six years, it was a no-brainer to skip this year's spring Networld-Interop show to attend a conference on electronics and the environment in San Francisco. Although I have no regrets about not catching the glitter or the $4.99 buffets, I was truly sorry to miss Broadcom's release of the StrataXGS Gigabit Ethernet switch architecture. With an architecture that is surprisingly similar to Marvell's Prestera EX products (reviewed here April 29, 2002), it updates and validates the concept of a shared-memory first stage coupled to a fast crossbar interconnect. The provisions for a stacking uplink channel included by both arch-rival chip makers also signals a shared belief in a revival of interest in the stacking pizza box-style products that were the darlings of the Fast Ethernet world in the late nineties.
I was not offered a briefing on the StrataXGS (presumably because Broadcom's busy N+I schedule did not coincide with mine), but even a cursory look at the press release and product briefs reveals a remarkable similarity between the Broadcom product and last week's offerings from Marvell. That's why I find it difficult to swallow Broadcom's laundry list of "industry first" claims for its otherwise excellent product.
While Broadcom should be justifiably proud of its chip set, it is not, in my opinion, "the first multi-layer Gigabit Ethernet switch with integrated high-speed stacking". With 12 ports apiece, multi-layer switching, and stacking capability, Marvell's EX120 and the BCM 5690 are probably the best to match up for an apples-to-apples comparison here. Although it is alpha-sampling a couple of months later than Broadcom, Marvell's EX family should have its Gigabit stacking switch chip in its lineup close enough to make any claims of "first" difficult to assert.
Before I go any further, please note that I do feel that while they are closely matched in many ways, Broadcom's offering a darned good product. In fact, it seems to be a bit more complete and integrated than the Marvell products, and if I'm not mis-reading both parties' somewhat vague product briefs, it's capable of scaling to larger capacities and numbers of ports. My difficulty here is that between somewhat inflated claims and lack of detail in the architectural description, it's tough to do a full comparison on a feature-by feature basis.
And while you're comparing them, be careful of Broadcom's bandwidth numbers as stated in its press release. Like many other companies, they count a full-duplex 1-Gigabit Ethernet port as having a 2-Gigabit capacity. This means that to properly compare claims to Marvell's more conservative 1:1 metrics, you have to scale each spec down by half.
All this being said, here are a few comparison points I was able to glean by studying specs and promotional materials. Both chips offer eight levels of per-port priority queuing. The Broadcom chips claim to switch at support layers 2 & 3 while providing classification at layers 2-7. Marvell's Prestera EX supports Layer 2/3 Routing as well, but, depending on which document you look at, it only does classification to Layer 4 or 5. Broadcom also appears to have a complete multi-layer reference design available in-house, while Marvell leaves anything above Layers 2/3 to an outside software vendor.
And now, a word about those uplinks. The Marvell chip has an integral uplink port with a full-duplex capacity of 16 Gbit/s to handle any additional packet header overhead that is tacked on, while the Broadcom's uplink appears to be only 10 Gbit/s.
When it comes to parts count, Broadcom scores more points because the 5690 & 5691 both use internal RAM for both switch tables and packet buffer memory. Marvell keeps its fast classification data and packet headers in an on-chip RAM, but buffers its packets in low-cost external SDRAM. From what I am able to extract, Broadcom's switch fabric chips also enjoy somewhat greater bandwidth capacity - even when you divide the press release specs by two.
Since they are so closely matched, it's hard to pick the absolute winner between these formidable opponents. To do this, you'll probably need to ask many more questions, including overall power consumption per port, the relative merits of their expansion architectures, and the real cost to implement a system that meets your product functional spec. Stuff like the maximum number of ports, the real level of traffic classification and management you require, and what software development tools you already are familiar with will all influence your decision.
StrataXGS products are selectively sampling this month. The BCM5690 and BCM5691 are in EBGA-480 and are volume-priced at $242 and $188, respectively. The BCM5670 and BCM5671 are in EBGA-600 and are volume-priced at $370 and $193, respectively.
If you end up poking around either of these impressive chip sets and reach any conclusions, I'd be interested to hear what you have to say. Please feel free to reach me at my old familiar address: lgoldberg@green-electronics.com. I'll be there waiting to hear about what you've found.
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