BPG | 11n DESIGN, IMPLEMENTATION AND OPTIMIZATION Meru Best Practices Guide Author | Robert Ferruolo | Technical Marketing Engineer Date | JULY 2010 Version | BPG_11n_v1.
TABLE OF CONTENTS MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization ........................................................................................................................................................................................................2 INTRODUCTION ............................................................................................................................................................4 Conventions ....................................
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Multi-floor Deployments ...................................................................................................................................16 Multi-controller Deployments ..........................................................................................................................17 Inter Controller Roaming (ICR) ................................................................................................
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization INTRODUCTION This document is intended to aid with the design, implementation and optimization of Meru 802.11n WLAN systems. Much of the information included in this document can be found scattered about in many different sources, or in some cases, not written down but known by a number of individuals that have a good deal of hands-on experience with Meru.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization GENERAL DATA COLLECTION Contact Information Getting a complete list of contacts upfront will save time later in the project. One of the most important contacts is the person or persons that will allow you to gain access to all of the areas needed to perform the initial walkthrough, the installation and then later the validation. Organizational Structure Here we collect data about the organization.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Existing Switch Specifications Meru Networks 11n AP300 series APs can operate at maximum 300Mbps dual stream 11N data rates on both Wi-Fi band radios 802. 11bgn and 802. 11an concurrently while using the most prevalent PoE switch port type, a single standard 802.3af or 802.3at port; however there are a few configuration considerations with regards to MIMO that need to be taken into account, please review chart below.
Pre-deployment Site Survey For Meru, pre-install site surveys are often not required. A site survey may be recommended if the environment is particularly challenging such as cruise ships, manufacturing facilities, cold storage facilities, warehouses, etc. A sample pre-site survey will aid in determining optimal AP placement. A sample pre-site survey is accomplished by identifying locations that are representative of the larger installation site. Sample site surveys are performed in those locations.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization One of the big advantages with Meru is that once we have identified the channels that have interference we can configure the Meru APs to be on different channels. Evaluate Current Wireless Environment This step involves leaning about the existing WLAN (if there is one).
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization We ask such questions as: • Which RADIUS servers are they using? • Will FIPS-140 be required? • Which authentication and encryption types are to be used? Keep in mind that the only two types of encryption that will realize the benefits of great data rate offered by 802.11n are clear (no encryption) and WPA2 per the specification. We also ask about network management user roles.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Another thing to consider when determining VLAN and ESS is whether or not multicast traffic will be supported. While you can have multiple VLANs per ESSID it is not recommended as a 1-to-1 mapping VLAN to ESSID is required to support multicast traffic (e.g. push to talk voice, streaming multicast video). AP Density We should be aware of how much APs overlap (i.e. the number of APs that can hear each other).
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization advantages of WLAN virtualization. For a more detailed look at this subject a link to a white paper on WLAN virtualization follow the link below. With Vport there is a “parent” BSS that is common to all clients for a given channel and ESS. Just to be clear the clients never associate to the parent BSS when Vport is configured. The parent BSS is used when load balancing is enabled which will be discussed later in this guide. http://www.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization There are a couple of general guidelines to follow when determining the number of channel layers needed to accommodate the type and number of clients expected. The recommendation is to design for 32 clients per radio. The following table provides recommendations for maximum clients per interference region for given beacon data rates.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization When clients move across a Vcell boundary a hard handoff will occur, similar to a client moving from AP to AP in a micro cell environment. This handoff will require a reauthentication and re-association (just as roaming between non virtualized APs would). This type of handoff is suboptimal and should be avoided if possible.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization DESIGN SCENARIOS This section introduces the various types of deployments and offers recommendation for various scenarios as listed below. There are many types of deployments such as typical office space, hotels, hospitals, outdoors, warehouses, stadiums, those that require location tracking, bridged (remote) APs, etc.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization at every location but configure half of them for different channels -- thus doubling the available client and/or throughput capacity. Let’s expand on the latter example further. We now have 4 radios to work with for each area of the network. Let’s assume that the customer has some mix of 11a, 11b, 11g and 11n clients.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Vcell/Vport outdoors Let’s take the example of a big open area. The spacing between APs is going to be much greater than that of indoors. If coverage is pervasive – with the recommended SNR and or signal strength levels (-65dBm for voice and -70dBM for data only) – then the recommendation is to enable virtualization.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Multi-controller Deployments Excluding when the Inter-Controller Roaming (ICR) feature is used, roaming between controllers would results in a hard handoff (i.e., Authentication/Association/DHCP) and a new IP address being issued to the client. Again, plan where hard handoffs will happen. Use natural boundaries. Another consideration is VLAN assignments in a multi-controller deployment.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization • AP200 using per station BSSID Vcell (There are no problems if AP200 is using shared BSSID Vcell) • AP300 using per station BSSID Vcell • AP200 and AP300 on the same channel (There are no problems if AP200 and AP300 are on different channels) • AP200 and AP300 on the same controller (There are no problems if AP200 and AP300 are on different controllers and each controller has a unique "controller index" configured.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Whether active-active or active-standby is deployed it is advisable to have the controller Ethernet ports connected to separate Ethernet switches (excluding the case where port bonding is used). Having the controller uplink ports “homed” to separate switches adds a level of wired network redundancy.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Four key characteristics of the N+1 redundancy model are as follows: 1. Slave and Master controllers that make up the N+1 cluster must all reside on the same IP network so the slave controller can gratuitously ARP on behalf of the IP address for the master controller for which it is providing backup services 2. APs must be a layer 3 hop away from their redundant controller cluster when N > 1 3.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Redundant Controllers via DNS Another way of implementing controller redundancy is with the help of DNS. This method is often preferred as it is simple to configure. The following shows how to set things up on the DNS. DNS entry wlan-controller = primary controller DNS entry wlan-controller2 = secondary controller RF Redundancy RF Redundancy is built into the typical Vcell deployment.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization This distance is important as we do not want the APs so close to each other such that there would be sideband or adjacent channel interference. Nor do we want them too far apart such that the coverage patterns for the various channels differ greatly. With two APs (or more) co-located we now have the ability have two channels in each spectrum. This allows us to have redundancy in the 2.4GHz band as well as in the 5GHz band.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization To begin the fingerprinting process floor plans are imported in the LM application. These floor plans are then divided into “locales”. In the screenshot below each green and blue section corresponds with a unique locale.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Bridge ESS Profiles Traffic can be tunneled back to the controller or be bridged locally. There is a setting in the ESS profile that sets the ESS to tunneled (default) or bridged. An AP300 can have both types of ESS profiles on a single radio. A tunneled ESS is generally the preferred method; however there are network designs where it makes more sense to keep data traffic local. This is where bridged ESS profiles make sense.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Deployment Process The first thing to keep in mind is that with any deployment (large or small) issues will arise. The success of an install very much depends on when the issues reveal themselves and how quickly they are rectified. This section suggests taking a methodical approach to deployments that will help ferret out issues early on in the process so they can be addressed in a timely manner.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Ceiling Mount Wall Mount AP300i Mounting The AP300i has six internal antennas. This AP can also be mounted on the ceiling or wall. The AP300i and AP300 are similar in many ways; one way they differ is in antenna patterns. The AP300 omni antennas (default) provide 360 degree coverage. The AP300i’s internal antennas provide 180 degree coverage (radiating from the top of the AP).
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization PROOF OF CONCEPT PLAN A good PoC plan includes testing (on a small scale) all of the WLAN system features and user applications in a design that is representative of the planned installation. The main object being to prove that the proposed system will be able to support the all of the functionality required. DEPLOYMENT PLAN We have all heard about installations that did not go well.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization Summary This guide was created to assist with the design, implementation and optimization of a Meru Network WLAN. While many of the methods suggested can be applied to general WLAN deployments, a number of recommendations were offered that are specific to Meru Networks WLANs. Many of these recommendations come by way of feedback from engineers that have performed numerous successful implementations over the years.
