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Deploying Mesh Networks for Wireless ISPs
Figure 1: A wired network with Wired Switch Stacks supporting AAA,
Authentication, VPN... Analogy to Wired Networks.
Figure 1 depicts a typical enterprise network setup. Workstations are connected to 10/100
ETHERNET switches, get their Layer 3 IP address from the DHCP server connected
on the same LAN, and are authenticated by the AAA server also on the same
LAN.
The LAN is made up using Layer 2 Ethernet switches which make workstations connected to switches 2, 3 to be considered to be part of the same LAN as the DHCP and the AAA server. The switches behaves as Layer 2 transparent bridges: clients appear to be on the same LAN to higher level Layer 3 (IP) protocol. Switches when connected form a network switch stack. Switches are responsible for a sub network, and the system as a whole is both scalable and stable.  Figure 2: A wireless network with Wireless switch stacks - supporting AAA, Authentication, VPN. In Figure 2, switches 2, 3 have been replaced by MeshDynamics Structured MeshTM 3-Radio Access Points + Backhaul integrated units. These units are specifically designed to make the wireless clients appear to be on the same LAN behaving exactly like Ethernet switches show in Figure 1 Note that the infrastructure connected to Switch 1 did not change at all. The DHCP, AAA, VPN servers behave exactly like the way before. Structured Mesh nodes are Layer 2 transparent bridges, compatible with all Layer 3 protocol and policy software. It also works transparently with all L3 security software. Note also that for WISP deployments, Figure 2 includes two new devices: the Bandwidth Shaping Device (BSD) allocates and manages WAN Bandwidth and the the Access Gateway Device (AGD) provides web redirection, payment and authentication services. The BSD and the AGD software work in conjunction with the AAA server and may be on the same server. The BSD logically sits between the LAN and the Firewall. The BSD allocates bandwidth based on WISP policies, and works in conjunction with the AAA server. Why Structured Mesh?
Distinctive Features and Benefits Lowest Operating Costs. After much controversy on the scalability of mesh networks competing mesh vendors conceded that their performance degrades by 1/n with each hop (best case) and - in the more typical case - it could be 1/2n. Conventional mesh networks do not scale well beyond 1-2 hops. The operating cost of Ethernet feeds every few hops starts to add up with large WISP deployments. Dynamic Channel Allocation: In the case of a one-radio system, all channels on the mesh network share the same channel- they are all on the same Basic Service Set (BSS). In our multi-radio system, some nodes switch to other channels to avoid interference from nearby nodes of other networks. [More] Standards Based Security: The mesh control software focuses on managing network topology and packet routing issues to meet latency/throughput requirements It does not tamper with the data packets in any manner. Standards based network security may be used without modifications. Note: Because we run at layer 2 just above the MAC level we automatically support security and performance extensions available the chip set. Example: AES security comes on the radio chip set. Seamless Roaming. In mobile situations, the normal process of disassociating with one AP and associating with another requires the system to update itself so communications to the STA are not dropped. This is automatic in our implementation of the 802.1d switch for our mesh nodes. [More] Mesh Network Health Monitor: The dynamic nature of the wireless medium makes centralized execution a non-scalable option. Our software control layer resides in each node of the network for distributed execution but - if desired - central control and monitoring. Information on local conditions can be sent to a Network Monitor which displays the health of the wireless network. That data helps detect abnormal conditions and also generate error reports. Radio and protocol agnostic: While it is equivalent to routing in the wired world our routing happens above the MAC level- it is both radio and protocol agnostic: Radios operating in other frequencies and using different protocols may be used. [More] Value Proposition for WISPs Competing mesh technologies lack the ability to distribute bandwidth over wide areas requiring multiple hops of the mesh backhaul. As a result, they need to be "re-charged" every few hops - through an Ethernet link. Costs of additional Ethernet links must be added to compare the overall deployment cost, especially for large Hotspots and city-wide HotZones requiring many nodes (see grids below).  In dense areas with many simultaneous accessing users per node, conventional mesh cannot deliver better than "dialup" bandwidth beyond 3 hops. A city wide wireless network therefore requires additional Ethernet links if each mesh is limited to 2-3 hops. Each Point to Point Ethernet link to the mesh adds increased capital equipment expenses. Also, each Ethernet feed service adds to the running cost of the network. For wide area, city wide deployments, Structured Mesh is thus by far the most cost effective means of providing VOIP and data coverage. Total costs of deployment for the WISP could be as low as $5 per month per subscriber in metro areas. The services can be sold to retail subscribers at existing rates currently charged by carriers, generally around $40/month or more. The deployment of Structured Mesh thus translates into significant strategic advantage for carriers. Subscribers enjoy the added advantage of a single ISP for indoors and outdoors. More Mesh Network Information:
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