Technology

N-Plus™ Architecture

The BandTel N-Plus™ Architecture: A Fault Tolerant High Transaction SIP Network

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Today's session initiation protocol (SIP) based VoIP networks have grown far beyond curiosity. The SIP trunking technology has radically changed the telecommunications industry and competes directly with legacy circuit-switched PSTN networks. With VoIP and SIP combined communications, an BandTel has developed an innovative approach is required to overcome issues relating to SIP throughput and redundancy.

The problems BandTel engineers have sought to resolve are:

1. Bandwidth Heavy - SIP utilizes an abnormally high rate of bandwidth for signaling; i.e. ~ 15 kbs for each sustained single call per second. That is a substantial amount of data processed during each call!
2. Character Clumsy - SIP is somewhat difficult for computers to handle. The protocol is entirely text and must be parsed using relatively intensive computer text manipulation software.

As a result of these issues, today's fastest servers are being challenged when attempting to rival switching speeds of SS7-ISUP based time-division multiplexing (TDM) networks. Thus far, the general solution has been to give end point SIP devices a hard-coded internet protocol (IP) address to the SIP carrier's proxy (i.e. the SIP switch). At the point where the SIP carrier's proxy reaches its capacity and can no longer handle any further load, the SIP carrier asks the end user to establish yet another IP address to yet another SIP proxy.

This approach is problematic in that it requires the SIP endpoint device to manage its own traffic termination. At the same time, this also creates single points of failure for the end user. BandTel has evaluated this situation and resolves the dilemma by using a clustered architecture.

The BandTel Matrix Solution
At the core of BandTel's network are pairs of domain name system (DNS) servers that direct the SIP end point user agents (UA). The BandTel DNS servers resolve to (what appears to be) a BandTel proxy address for the UA. In reality, the UA is pointed to a new concept in SIP communications. BandTel identifies this a signaling transfer point (STP)

This mnemonic/name was adopted from SS7 space because BandTel engineering realized it did something similar to its SS7 counterpart. Specifically, BandTel STPs (deployed in groups for redundancy) actually decide which one of N proxies in the BandTel proxy matrix will be used to process a given SIP call for a given SIP endpoint.

The STP allows BandTel to deploy a fine-tuned matrix of "N" SIP proxies to handle whatever data load is required for any given task at hand. There is no limit to the calls per second (CPS) processing power within the BandTel signaling domain. Furthermore, there is no need for the user agent (UA) to hard-code a carrier proxy address into the configuration schema. The UA no longer needs to be concerned about an interruption to the service or low-quality voice calls if a proxy has the capacity to handle its load.

Using this N-Plus™ approach to enhance business voice communications also eliminates single points of failure, and enhances redundancy to the Nth degree. BandTel's N-Plus™ Architecture solves some major technical hurdles just now surfacing in the SIP market place.

The advanced technology behind the N-Plus™ Architecture positions BandTel as a global leader in VoIP communications innovation and design.

N-Plus™ Solves the Problem
As mentioned prior, BandTel has set in place a matrix of proxies with each call being able to use any of the proxies in that matrix. This presents another issue: each proxy must now know registration and routing information for all the SIP endpoints on the BandTel SIP network.

To solve this problem, BandTel has created the highly effective "Synchor" and "Registrar" services. These two services run redundantly in real time, keeping the registration and routing information current and equal across all BandTel proxies. Again, BandTel has realized another communications industry first in its approach to dealing with the problem of high capacity telephony signaling on an IP network. The ability to be able to synchronize all proxies in real time creates a single virtual switching machine with unlimited call processing potential.

Finally, BandTel ties this unique N-Plus™ Architecture™ back to the public switched telephone network (PSTN) with a wide spectrum of tier-one TDM national and international carriers for network access. This gives advanced routing and SIP termination/origination options for all BandTel customers to or from anywhere in the world.

BandTel’s innovative N-Plus™ Architecture meets athe critical need for high volume SIP customers by offering:

• High capacity throughput
• PSTN or better redundancy and reliability
• Multiple routes to any global destination
• The "least cost" route to any given destination
• Ease of connection to the PSTN

Acting as a high-capacity homologated SIP switching point for SIP endpoints, and connecting those endpoints to the world, BandTel is now the "virtual IP central office to the world" for the SIP end-user.