Ethernet varies, with no frame smaller than 64 octets (bytes) and no frame larger than 1518 octets. If two bandwidth- reserved frames arrive at a single-queue router simultaneously, the first one to enter the buffer is the first in line for transmission. Because the whole frame must be sent, the second stream is held in queue. If the first frame comes close to Ethernet's maximum 1518 octet frame size, the second application's payload will be noticeably delayed. Because of this, RSVP-enhanced IP networks fare poorly in comparison to Standards for Conferencing over IP Networks ATM, which uses very small cells (53 bytes), and thereby makes QoS guarantees more realistic. The real-world effect is that many routers must be upgraded or replaced for widespread deployment of RSVP. The two largest router/switch manufacturers, Cisco (San Jose, California) and Bay Networks (Billerica, Massachusetts), have long since made their products capable of responding to RSVP requests. Cisco was first to market, with its IOS software that began shipping in September of 1996. The two groups most likely to buy and install those upgrades are private corporations and Internet service providers. The Internet service provider (ISP) BBN Planet (now GTE), Cambridge, Massachusetts offered the first commercial implementation. 1996, RSVP was largely a test-bed implementation. Vendors, working collaboratively, tried out many different implementations. Most early RSVP implementations left it up to the user to set load and delay parameters. This may work in an experiment, but when RSVP is widely deployed, this approach will quickly fall apart. Users, perennially bandwidth-starved, would promote their application to the front of the service line. In response, vendors are developing offerings in such a way that network administrators (often the decision makers when it comes to selecting products) have the ability to charge for higher-priority service and therefore, to limit congestion. The IETF is developing specifications to allow users to assign pri