-In this work, we measure Wireless Local Area Network (WLAN) voice performance and capacity. While most WLAN applications today are data centric, the growing popularity of Voice over IP (VoIP) applications and the trend towards convergence with cellular networks will catalyze increased voice traffic. Since voice applications compete not only with each other, but also with data applications for WLAN bandwidth, quantifying voice performance and capacity in the presence of simultaneous data traffic is an important issue. We offer a practical investigation of the 802.11b MAC layer's ability to support simultaneous voice and data applications. We quantify VoIP capacity for standard WLAN networks, indicative of those already in the field, as well as evaluate the practical benefits of implementing backoff control and priority queuing at the access point. Conclusions are drawn based on an extensive set of real-world measurements conducted using off-theshelf equipment in an experimental testbed. I INTRODUCTIONOnce only seen within the enterprise, Wireless Local Area Networks (WLANs) are increasingly making their way into residential, commercial, industrial and public areas. Examples of such environments are hotels, airports and coffee shops, which typically have a floating end user population. University campuses and conference settings also benefit from WLANs since they provide flexible connectivity and network access at reduced costs. While the majority of traffic in WLAN deployments is data, we expect that voice will be an increasingly important application and a significant driver for WLAN adoption and integration, particularly as voice over IP (VoIP) applications flourish. Additionally, voice will be especially important in vertical industries such as construction, healthcare, and banking, etc. Therefore it is crucial to understand voice performance in WLANs. Furthermore, since WLAN endpoints share a common transmission medium, voice applications must compete with data applications for access and bandwidth. As such, voice quality and capacity can be significantly affected by the simultaneous transmission of data traffic in these networks. So it is also critical to understand the effects of data transmissions on voice performance and capacity.We focus exclusively on IEEE 802.11b [1], the most popular and prominently deployed WLAN standard. We measure the achievable voice performance and capacity using an experimental testbed consisting of commercially available, off-the-shelf components indicative of those that have already been deployed. With such a large legacy base for 802.11b equipment, especially among residential and enterprise customers, we believe that this approach provides the most immediately relevant results.In addition to standard 802.11b, we investigate MAClayer and queuing mechanisms , which can be easily implemented and can improve voice performance. Specifically, we measure the effects of backoff control and priority queuing (BC-PQ), as provided by [2]. Using both the standard and additional...

Toshiba's Router Architecture Extensions for ATM : Overview Status of this MemoThis memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. Distribution of this memo is unlimited. AbstractThis memo describes a new internetworking architecture which makes better use of the property of ATM. IP datagrams are transferred along hop-by-hop path via routers, but datagram assembly/disassembly and IP header processing are not necessarily carried out at individual routers in the proposed architecture. A concept of "Cell Switch Router (CSR)" is introduced as a new internetworking equipment, which has ATM cell switching capabilities in addition to conventional IP datagram forwarding. Proposed architecture can provide applications with high-throughput and low-latency ATM pipes while retaining current router-based internetworking concept. It also provides applications with specific QoS/bandwidth by cooperating with internetworking level resource reservation protocols such as RSVP.

This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. Distribution of this memo is unlimited. AbstractThis memo discusses Flow Attribute Notification Protocol (FANP), which is a protocol between neighbor nodes for the management of cut-through packet forwarding functionalities. In cut-through packet forwarding, a router doesn't have to perform conventional IP packet processing for received packets. FANP indicates mapping information between a datalink connection and a packet flow to the neighbor node and helps a pair of nodes manage the mapping information. By using FANP, routers (e.g., CSR; Cell Switch Router) can forward incoming packets based on their datalink-level connection identifiers, bypassing usual IP packet processing. The design policy of the FANP is;(1) soft-state cut-through path (Dedicated-VC) management (2) protocol between neighbor nodes instead of end-to-end (3) applicable to any connection oriented datalink platform BackgroundDue to the scalability requirement, connection oriented (CO) datalink platforms, e.g., ATM and Frame Relay, are going to be used as well as connection less (CL) datalink platforms, e.g., Ethernet and FDDI. One of the important features of the CO datalink is the presence of a datalink-level connection identifier. In the CO datalink, we can establish multiple virtual connections (VCs) with their VC identifiers among the nodes. When we aggregate packets that have the same direction (e.g., having the same destination IP address) into a single VC, we can forward the packets in the VC without IP Nagami, et. al. Informational [Page 1]

The Asynchronous Transfer Mode Label Switching Router (ATM-LSR) is one of the major applications of label switching. Because the ATM layer labels (VPI and VCI) associated with a VC rewritten with new value at every ATM switch nodes, it is not possible to use them to identify a VC in label mapping messages. The concept of Virtual Connection Identifier (VCID) is introduced to solve this problem. VCID has the same value at both ends of a VC. This document specifies the procedures for the communication of VCID values between neighboring ATM-LSRs that must occur in order to ensure this property.

The advent of the mobile wireless Internet has created the need for seamless and secure communication over heterogeneous access networks such as IEEE 802.11, WCDMA, cdma2000, and GPRS. An enterprise user desires to be reachable while outside one's enterprise networks and requires minimum interruption while ensuring that the signaling and data traffic is not compromised during one's movement within the enterprise and between enterprise and external networks. We describe the design, implementation and performance of a Secure Universal Mobility (SUM) architecture. It uses standard protocols, such as SIP and Mobile IP, to support mobility and uses standard virtual private network (VPN) technologies (e.g., IPsec) to support security (authentication and encryption). It uses pre-processing and make-before-break handoff techniques to achieve seamless mobility (i.e., with little interruption to users and user applications) across heterogeneous radio systems. It separates the handlings of initial mobility management and user application signaling messages from user application traffic so that VPNs can be established only when needed, thus reducing the interruptions to users.