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FOUNDRYNETNo. 001SEPTEMBER 2026FOUNDRY ARCHIVE

Original page: www.foundrynet.com/products/l3backbone/bigiron/index.html (archived)

Foundry BigIron: Layer 3 Backbone Switch Family

BigIron was the Foundry Networks chassis switch line for campus and data-center backbones: wire-speed Layer 2/3 forwarding, redundant management and hot-swappable line cards, from the late 1990s through the BigIron RX.

On this pageWhat BigIron wasGenerations and architecturesJetCore and what it changedChassis featuresTypical deploymentsWhat replaced itRunning one todayQuestions

01 /What BigIron was

BigIron was the modular backbone switch that Foundry Networks sold from the late 1990s. Where FastIron covered the wiring closet, BigIron took the core and distribution layers: a chassis with redundant management modules, hot-swappable line cards, and Layer 2 and Layer 3 forwarding in hardware. The Layer 2 versus Layer 3 page explains why this mattered at a time when routing in software was the bottleneck.

The name refers only to the Foundry product line. Two IronWare images existed for the chassis, a switch image and a router image, and the same hardware could run either. That split later carried over to the ServerIron and NetIron lines.

02 /Generations and architectures

BigIron generations. IronCore, JetCore and Terathon were Foundry names for successive ASIC designs.
ModelApproximate yearsArchitectureNotes
BigIron 4000 / 80001998 to early 2000sIronCore, later JetCore modules4 and 8 slot chassis; the original campus core
BigIron 15000Around 2000 to 2005IronCore and JetCoreLarge chassis for ISP and data-center aggregation
JetCore modules2001 onwardJetCoreWire-speed ACLs, rate limiting and sFlow in hardware
BigIron MG8Around 2003Terathon (reportedly first use)Early 10 Gigabit chassis, 8 slots
BigIron RX-4 / 8 / 16Around 2005TerathonDense Gigabit and 10 Gigabit, redundant fabrics
BigIron RX-32Around 2007TerathonLargest RX; continued under Brocade
BigIron timelineBIGIRON TIMELINE1998BigIron 4000 and 8000 chassis ship2000BigIron 15000 for large cores2001JetCore ASIC generation announced2003BigIron MG8, early 10 Gigabit chassis2005BigIron RX series on Terathon2008Brocade acquires Foundry2010Brocade MLX takes over the core role
Approximate dates from press releases and archived product pages.

03 /JetCore and what it changed

JetCore, announced in 2001, was the second Foundry ASIC generation. Its significance was that features previously handled by the management CPU moved into the forwarding path: access control lists, rate limiting, quality of service marking and sFlow sampling all ran at line rate on JetCore modules. Foundry was an early backer of sFlow, and JetCore hardware is one reason the protocol spread through university and ISP networks. Older IronCore modules coexisted in the same chassis but forwarded some features in software.

04 /Chassis features

  • Management redundancy: two management modules, one active and one standby, with configuration synchronised between them.
  • Hot-swappable line cards: Fast Ethernet, Gigabit and later 10 Gigabit modules could be replaced without powering down the chassis.
  • Layer 3 protocols: OSPF, BGP4, RIP, IS-IS on later releases, multicast routing, and VRRP and VSRP for gateway redundancy.
  • Layer 2 features: VLANs, spanning tree variants, trunk groups and metro ring protocol on later images.
NOTE

FoundryNet is an independent product archive, not affiliated with Foundry Networks, Brocade, Broadcom or Extreme Networks. Feature lists here are qualitative; consult archived release notes for the exact image that a given unit runs.

05 /Typical deployments

BigIron chassis were common in university cores, where price per Gigabit port and sFlow support counted, in regional ISPs as aggregation switches, and in high performance computing clusters as the Ethernet fabric before InfiniBand dominated. Several large web properties of the early 2000s ran BigIron in their data centers. The MG8 and RX generations were pitched at 10 Gigabit aggregation and at Internet exchange points.

06 /What replaced it

After the December 2008 acquisition, Brocade kept selling the BigIron RX for several years and issued IronWare updates for it, but positioned the NetIron MLX and later the MLXe as the core platform. The RX reached end of sale under Brocade around the middle of the 2010s; the exact dates depend on model and should be checked against archived Brocade notices. See the Brocade acquisition page for the corporate side.

07 /Running one today

A populated BigIron RX draws well over a kilowatt and sounds like a small server room. The smaller 4000 and RX-4 chassis are the only ones practical outside a rack with dedicated cooling. Firmware is no longer distributed and the last releases carry unpatched vulnerabilities in SSH, SNMP and the web interface, so isolate the management plane. For a lab the unit is still a fast Layer 3 backbone with real hardware ACLs and sFlow export, and its IronWare CLI transfers directly to later Brocade and Ruckus gear.

08 /Questions

What was the BigIron used for?

Campus and data-center backbones. It was a chassis Layer 3 switch that aggregated wiring closet switches such as the FastIron, routed between VLANs at wire speed and handled OSPF or BGP toward the WAN. ISPs also used it for customer aggregation.

What is the difference between IronCore, JetCore and Terathon?

They are three generations of Foundry forwarding ASICs. IronCore was the original. JetCore (2001) moved ACLs, rate limiting and sFlow into hardware. Terathon powered the 10 Gigabit MG8 and the RX series with higher fabric capacity and larger tables.

Did the BigIron survive the Brocade acquisition?

The RX series did, for several years. Brocade sold and supported the BigIron RX into the mid-2010s while steering core customers toward the NetIron MLX and MLXe. The older 4000, 8000, 15000 and MG8 were already at or past end of life by 2008.

Is a BigIron worth running in a homelab?

Only if power and noise are not constraints. The switch offers true wire-speed Layer 3, hardware ACLs and sFlow, and the CLI matches later Brocade and Ruckus FastIron devices. Budget for hundreds of watts idle and treat the management interfaces as untrusted.

Can the BigIron run both switch and router images?

Yes. IronWare shipped as a Layer 2 switch image and a full Layer 3 router image for the same hardware. The router image is what most cores ran, and it is the one worth loading in a lab if the flash still holds a copy.

Sources

  • Foundry Networks press releases on BigIron 4000, 8000, 15000, MG8 and RX announcements, 1998 to 2007
  • Foundry Networks JetCore architecture announcement and application note, 2001 (historical)
  • Original Foundry BigIron product pages and datasheets (historical, archived)
  • Brocade BigIron RX end of sale and end of support notices (successor vendor, mid-2010s)