The VoIP Peering Puzzle�Part 26: SBC Architectures�Acme Packet

In our last group of tutorials, we examined seven Session Border Controller (SBC) functions that the IETF’s Session Initiation Proposal Investigation (sipping) Working Group documented in their recently issued Internet Draft document titled Requirements from SIP (Session Initiation Protocol) Session Border Control Deployment (see (Remember that Internet Draft documents are considered “work in progress,” and are therefore subject to change.)

To quickly review, these functions were Topology Hiding, which is designed to maintain the proprietary of the private network topology; Media Traffic Shaping, which modifies the session description messages, thus changing the characteristics of the network traffic (see Part 21 for details); Fixing Capability Mismatches, which corrects minor differences in protocol implementations; and Maintaining SIP-related NAT Bindings, which addresses the issue of transporting VoIP traffic through a Network Address Translation (NAT) device (see Part 23 for details); Access Control, which applies access security to either the signaling or both the signaling and the media functions; Protocol Repair, which fixes incompatible signaling messages before forwarding; and Media Encryption, which performs an encryption/decryption function at the edge of the network (see Part 24for details).

Going forward, the Peering Puzzle series will extend the discussion regarding SBC functionality, but from a more practical perspective—looking at SBC product capabilities from various networking vendors.

First up is Acme Packet, Inc., headquartered in Burlington, Mass., and a firm that is perhaps unique within the Session Border Controller marketplace, in that SBCs are their business, as opposed to other firms that consider SBCs to be an elementof their business.

Acme views SBCs as standalone products that need not be part of a larger product suite; they are fully functional on their own and provide neutral support for multiple architectures, thus fulfilling a full range of critical requirements that include: security, service-reach maximization, service-level-agreement (SLA) assurance, revenue and profit protection, and regulatory compliance.

As a result of this singular focus, Acme claims a position of leadership within the SBC market, with its Net-Netfamily having been selected by over 360 service providers in 75 countries to satisfy the critical security, service assurance, and regulatory requirements in wireline, cable, and wireless networks. Acme’s customer list is impressive, and includes 23 of the top 25, and 72 of the top 100 service providers in the world.

These deployments support multiple applications—from VoIP trunking to hosted enterprise and residential services to fixed/mobile convergence; multiple protocols—SIP, H.323, MGCP/NCS and H.248; and multiple border points—interconnect, access network, and data center. (NCS is the Network Call Signaling protocol based upon MGCP and developed by Cablelabs, Inc., as part of the PacketCable architecture for the transmission of two-way multimedia traffic over existing cable networks (see

This product strategy must be working, as Acme’s 2006 revenues jumped from $36 million to $84 million year-over-year, and net income went from zero to $29 million. And these financial goals were reached with only 250 employees spread across 20 countries around the globe.

Acme Packet’s Net-Net family of SBCs supports next generation, converged fixed/mobile architectures including those from 3GPP IMS (, ETSI TISPAN (, ATIS (, the Multi-Service Forum (, PacketCable (, and the DSL Forum (

Acme offers two hardware platforms, the Net-Net 4000 series, and the Net-Net 9000 series. Both platforms may be configured to support either an integrated or a decomposed SBC model. Using the integrated model, the products support both signaling and media control within the platform. The decomposed configuration includes a signaling control-only, and a media control-only option.

There are also five different configuration options: a Session Director, an integrated SBC with multiprotocol signaling and media control; a Border Gateway, a decomposed SBC with media control only, which uses an H.248 control interface to master an Acme Packet Controller or third-party SIP signaling element; a Session Controller, a decomposed SBC with SIP signaling control only, which uses a H.248 control interface to slave an Acme Packet Border Gateway or third-party media proxy/relay; a Signaling Firewall, a decomposed SBC with SIP signaling security and other control functions; and a Session Router,a decomposed SBC providing SIP routing and load balancing only.

The Net-Net 4000 series is the carrier-class product that Acme Packet claims is the world’s most widely deployed SBC. This unit is packaged in a 1U rack-mounted system, with signaling performance up to 333 calls per second, capacity for up to 32,000 media sessions, and either two or four 1,000 Mbps, or eight 10/100 Mbps Ethernet interfaces. The Net-Net 4000 PAC is a pack of up to nine 1U Net-Net 4000 series SBCs that perform as one logical unit, and take up only 9U of rack space.

The Net-Net 9000 series is the next-generation higher capacity unit, packaged in a 7U racked mounted system, with signaling performance up to 1,150 calls per second, up to 128,000 media sessions, up to 16,000 transcoded calls (i.e. converting between wireline and wireless codec formats), and up to eight active 1 Gbps Ethernet interfaces.

Acme Packet has also developed the Net-Net EMS (Element Management System), which enables service providers to rapidly deploy and easily manage one or more Net-Net SBCs.

Further details on the Acme Packet SBC architecture and products can be found at next tutorial will continue our examination of vendors’ SBC architectures.

Copyright Acknowledgement: © 2007 DigiNet Corporation ®, All Rights Reserved

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