VLANs
VLANs are an everyday staple in networking today. We wanted to discover exactly how, and when, they came about. In everyday homelab/prosumer, small business and many enterprise networks, routers and switches use VLAN tags, which were defined by the 802.1Q standard. This feels like a concept that has been around forever, and I was a bit surprised that the 802.1Q standard wasn’t published until 1998.
However, the rather late completion of 802.1Q meshes with one of the inspirations I had for first looking into the topic. I worked at an organization that underwent a very involved enterprise network rebuild around the year 2000, in which many subnets were setup for security and isolation. A pair of Nokia Checkpoint firewalls were used for routing and security policies between subnets. Each subnet had one or more physical switches dedicated to it. In the core datacenter site, this physically looked like a slew of 3Com SuperStack switches – many of which only had a few cables connected. So, I’m pretty sure the original network engineers of this setup had not used VLANs in this build and led to me wondering exactly when VLANs were commonly available. Its hard to imagine today, but VLANs were a new concept at that point in time.
IEEE
We started our research by looking to the IEEE. Fortunately, a lot of primary source materials are online from the IEEE, organized by year:
https://www.ieee802.org/1/files/public/
And while there are some index files, they are plain text (no hyperlinks) and have very brief descriptions. We started looking through these by hand which pointed to many relevant companies and individual people to research further. To better sort through the IEEE files, we used AI to process all of the files from 1994-1998, summarize each, and put them into a sortable and searchable index: https://files.serialport.org/ieee802/ieee802_index.html
Alantec
One of the first relevant VLAN-related presentations we came across was from John Wakerly, who served as CTO at Alantec. We were surprised to see how involved Alantec was in VLAN development because we had never heard of this company before– I even misread it at first and got thrown off because I was searching for them as the name “aTlantec”, then finally realized its “A – LAN – TEC(h)”, clever.
We were able to get in touch with John by email and he provided a lot of key insight about Alantec and early Ethernet networking. He shared quite a bit of information – and even sent us some hardcopy documents about architecture, market, VLANs, etc. from an investor’s point of view. We’ll work on posting more of that online as well.
A key point in finding the earliest virtual LAN implementation was Alantec’s MLS (Multi-LAN Switch). It supported “bridge groups” to isolate networks, so we think this was the first VLAN-esque product, it was released in 1989 or 1990. Ben found an article from Datamation (Datamation Vol 39, Issue 16) which also mentioned Alantec as the first vendor with a virtual LAN capability:
The first hub with something like a virtual LAN, analysts say, was the PowerHub from San Jose-based Alantec Inc., which had a virtual LAN function a year before UB. Alantec, however, called the function “port subnet mapping,” which is a little like calling sushi “cold, raw fish.”
Alantec’s most successful product was the PowerHub, released in 1992 (Network World Mar 16, 1992). John has a PowerHub 3500 and shared some pictures and description of its architecture. Notably, the PowerHub performed routing for IP and IPX (both mentioned in Network World in 1993), making it the first or one of the first multilayer switches.
John introduced us to Mano Murthy, who was one of the early employees at Alantec starting in 1988. He was their first software engineer and was gracious to join us for a video interview, where he talked about early virtual LAN development at Alantec.
So, why hadn’t we heard of Alantec? The company was rather successful with their PowerHub product, they went public in 1994. In 1995 their revenue was $50MM and in December of 1995 it was announced they would be acquired by Fore Systems at a $650MM valuation. The PowerHub lived on, rebadged under the Fore name, however the focus of Fore was purely on ATM.
Cisco
Another person of interest from our IEEE research was Martin McNealis, who held several roles at Cisco including IOS Product Manager. In July of 1995 he delivered a presentation at an IEEE Conference in Maui titled: 1995 – The Year of the Virtual LAN. I appreciated the simple and bold title. In the presentation he said VLANs are over-hyped and under-defined, and went in to some detail about the 802.10 option. We were able to get in touch with Martin, and he shared his perspective with us in a video interview which was very insightful.
One of the key areas he shed some light on was 802.10. 802.10 was actually finalized first in 1992 as a security standard for LAN/MAN networks and added security identifiers to frames. Cisco had added 802.10 support to its products, and Cisco tried to rally support for 802.10 to be adapted to handle VLANs. This did not happen, as the 802.10 WG seemed reluctant about removing encryption for their view of a VLAN implementation (1996 letter).
ISL: Cisco acquired Crescendo Communications in 1993 which became their Catalyst family of switches. Crescendo had developed ISL (Inter-Switch Link) to handle VLANs. ISL only supported up to 1000 VLANs, it worked by encapsulating the Ethernet frame with a new 26-byte header and 4-byte trailing CRC. So, why did ISL not become a standard? The industry wanted to develop something new and open in nature — and the 30 byte overhead from ISL was viewed as very “heavy”. In contrast, an 802.1Q frame only has 4 additional bytes added.
The rest is history
The 802.1Q working group was formed in 1996, and the standard published in 1998. The standard is vastly more complex than I first expected, as it worked with other layer2 networks (FDDI + Token Ring). The 802.1Q header also adds a field for PCP (Priority Code Point) which is used for the 802.1p class of service (CoS) – a topic intertwined with VLAN development, but we decided not to expand into in this video.
802.1ad was the next major development in VLANs – commonly called “Q in Q” it allows for frames to be double tagged. This is mainly used in service provider networks, so a service provider can tag customer-facing ports (an “outer tag”), and customers can tag frames as well (this is referred to as the “inner tag”), resulting in a SP delivering customer traffic from point A to Z with the customer’s VLAN tags intact. The 802.1ad standard was approved in Dec 2005, and published in May 2006.
Acknowledgements
Special thanks to collaboration with: John Wakerly, Mano Murthy, Martin McNealis and Kevin Tolly.
References
Here are reference materials we used in our research for this video.
Wakerly, John. (2025). Email correspondence.
Murthy, Mano. (2025). Interview conducted by Serial Port.
McNealis, Martin. (2025). Interview conducted by Serial Port.
Rollerblade® Time Capsule: Spirit Intro 1995. https://www.youtube.com/watch?v=OV8NoZaWexU
Cotton, C., Bogovic, T., & Leland, W. (2010). W. DAVID SINCOSKIE , PIONEER OF PACKET COMMUNICATIONS. IEEE Xplore. https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=5673062
Bellcore property photo. https://www.edgewoodproperties.com/commercial/ericsson-building-hoes-lane-commons/
Sincoskie, D. W. (2002). Broadband Packet Switching: A Personal Perspective. IEEE Xplore.
Sincoskie, D. W., Cotton, C. (1988). Extended Bridge Algorithms for Large Networks. IEEE Network.
Murthy, M., Wakerly, J., Laursen, A. I. (1993). Communication apparatus and methods. https://patents.google.com/patent/US5515376A/en?oq=US-5515376-A
IEEE 802.1 docs. https://www.ieee802.org/1/files/public/docs1995/
IEEE 802.1 docs. https://www.ieee802.org/1/files/public/docs1996/
IEEE 802.1 docs. https://www.ieee802.org/1/files/public/minutes/jan96/
IEEE 802.1 docs. https://www.ieee802.org/1/files/public/minutes/mar96/
IEEE 802.10-1992. https://standards.ieee.org/ieee/802.10/1153/
IEEE 802.1Q-1998. https://standards.ieee.org/ieee/802.1Q/1039/
Photos of AGS and Catalyst 5000. Cisco Archive. http://ciscoarchive.lunaimaging.com/
Configuring Routing Between VLANs with Inter-Switch Link Encapsulation (2008). https://www.cisco.com/en/US/docs/ios/lanswitch/configuration/guide/lsw_cfg_switch_encap.pdf
Architecture and Design of Metro Ethernet over Optical Transport Networks. (2003). Cisco. https://www.cisco.com/c/dam/global/fr_ca/training-events/pdfs/Architecture_and_Design_of_Opt_Transport.pdf
Network Protocols Handbook. (2005). Javvin Technologies, Inc.
Cheriton, D. (1995). Virtual LAN Management Protocol (VLMP) Draft RFC. https://www.ieee802.org/1/files/public/docs1995/s95n052.pdf
Nanni, Dan. (2025). VLAN Port Types: Trunk vs. Access. https://study-notes.org/vlan-port-types.html
Advanced Traffic Management Guide. (2008). HP. https://community.hpe.com/hpeb/attachments/hpeb/switching-e-series-forum/210/1/c02563813.pdf
Multiple VLAN Registration Protocol. (2025). Juniper Networks. https://www.juniper.net/documentation/us/en/software/junos/multicast-l2/topics/topic-map/mvrp.html
VXLAN Data Center Interconnect Using EVPN Overview. (2025). Juniper Networks. https://www.juniper.net/documentation/us/en/software/junos/evpn/topics/concept/vxlan-evpn-integration-overview.html
Khatri, Paresh. (2018). MPLS-based Metro Ethernet Networks. https://www.sanog.org/resources/sanog32/SANOG32_Tutorial-MPLS_Based_Metro_Ethernets.pdf
