This document provides deployment guidance for Cisco® Accelerated 3G, a solution that combines the 3G connectivity of the Cisco 3G Wireless WAN (WWAN) High-Speed Interface Card (HWIC) and the WAN link acceleration capabilities of the Cisco Network Capacity Expansion (NCE) service module. The document presents performance results achieved by combining the two technologies, outlines the required Cisco IOS® Software configuration, and describes deployment in a typical small branch office. The goal of this guide is to demonstrate that Cisco NCE combined with Cisco 3G WWAN HWIC achieves significantly higher data rates for TCP applications than a native 3G WWAN connection and to make the deployment of this solution fast and predictable.
3G Wireless Limitations
Whether used for primary access or as a backup link to a traditional wireline connection, 3G WWAN connectivity offers a compelling alternative to the various wireline WAN services. The primary benefits of 3G WWAN include:
• Secure wireless connectivity to the enterprise network and the Internet
• Cost-effective solution when compared to wireline alternatives
• Quick and nonintrusive service setup, resulting in faster time to market
• Greater network availability from divergent wireless and wireline network paths
Despite these benefits, the current generation of 3G wireless technologies has limited bandwidth, the main drawback in using 3G for primary access to the WAN. The theoretical downlink speed for the latest commercially available 3G protocols is in the range 3 to 4 Mbps. The uplink speed allows up to 2 Mbps. In practice, 3G links achieve 50 to 60 percent of their theoretical limits. In addition, high latency, asymmetric data rates, and high packet loss impact the response time of applications delivered over a 3G link. The Cisco NCE service module accelerates data transfer rates on WAN links that have limited bandwidth, high latency, and high error rates such as 3G and satellite links. This document shows that by combining Cisco NCE and 3G HWIC, the data rate on a 3G link can be increased to 200 to 400 percent of its typical rate.
Cisco 3G WWAN HWIC
The Cisco 3G WWAN HWIC is a high-performance 3G interface card available for Cisco 1841, 1861, 2800 Series, and 3800 Series Integrated Services Routers. Suitable for both backup and primary WAN access, the Cisco 3G WWAN HWICs support the latest CDMA and GSM/UMTS standards (EVDO Rev A and HSDPA) and are backward compatible with the widely deployed 2G and 2.5G networks (1xRTT and GPRS and EDGE). The Cisco 3G WWAN HWIC is tightly integrated with the services provided on the award-winning Cisco Integrated Services Routers, which deliver secure data, voice, video, and mobility services.
Main Features and Benefits
• Broadband data rates up to 3.2 Mbps with EVDO and 3.6 Mbps with HSDPA
• Support for latest CDMA and GSM/UMTS standards (EVDO Rev A and HSDPA)
• Embedded mini peripheral component interconnect (PCI) express cellular modem from Sierra Wireless
• Cisco IOS® Software commands to activate, provision, and manage the modem
• Upgradeable modem firmware (not bundled with Cisco IOS Software)
• Multiple external antenna options for in-building deployments
• Target applications: WAN backup, rapid deployment, and portable applications
The Cisco NCE service module is a transparent proxy that increases data transfer rate on a WAN link and improves response times of remotely hosted applications. The service module accelerates performance of any TCP application delivered over a wireless or wireline WAN. Cisco NCE is suitable for branch offices and remote sites with WAN connections that have limited bandwidth, high error rates, or high latency such as 3G or satellite links. The service module is available for Cisco 1841, 2800 Series, and 3800 Series Integrated Services Routers, and the Cisco NCE is tightly integrated with the services provided on these award-winning products.
Main Features and Benefits
• Typical 4X WAN link throughput increase and remote application response time acceleration
• TCP optimization through Stream Control Transmission Protocol (SCTP) encapsulation, TCP session multiplexing, and other optimizations such as localized packet flow control
• Integration into Cisco Express Forwarding (CEF/dCEF) helps ensure transparency to other Cisco IOS Software features such as firewall, IPS, ACLs, QoS, and others
• Hub-to-spoke and meshed deployments with up to 10 concurrent remote peers
• No additional mechanical parts in the solution while offering a robust bypass mechanism, reducing network disruption in case of failure
• Target applications: any TCP-based applications delivered over a WAN
An outgoing TCP traffic flow routed through the 3G WWAN interface is intercepted by the Cisco NCE module. The module acts as a transparent performance-enhancing proxy (PEP) that terminates the sender's TCP session locally, compresses and bundles the sender's data, sends the data to a remote peer encapsulated with SCTP, unbundles and decompresses the data, and establishes a new TCP session remotely to deliver the data to its destination, while fully maintaining the end to end semantics of the original TCP session. Figure 1 shows the end-to-end deployment architecture of Cisco NCE.
Figure 1. Cisco NCE Deployment Architecture
Repeated testing shows that data throughput and remote application response time on a 3G link increases three to five times when the Cisco NCE service module and Cisco WWAN HWIC are combined in a single solution. Table 1 shows forward-link performance improvements for various 3G wireless standards. The data was collected by running 44 concurrent HTTP file download applications, resulting in 100 percent bandwidth utilization. Figure 2 provides graphical depiction of the gain achieved with the Cisco Accelerated 3G solution in comparison to actual performance of a native 3G connection for the HTTP-only-traffic profile.
Table 1. Downlink Data Rate for 3G and Cisco Accelerated 3G in a Typical 15- to 25-User Remote Office with an HTTP Application Utilizing 100% of Available Bandwidth (Results Are from 18 Concurrent Users Each Generating Three Concurrent TCP Connections)
3G Standard
3G Theoretical Data Rate (kbps)
3G Actual Data Rate (kbps)
Cisco Accelerated 3G Data Rate (kbps)
Gain Factor (accelerated/actual)
Bandwidth Increase (kbps)
Wireline Equivalent
EDGE
237
177
560
3.2
383
1/3T1
HSDPA
700
492
1242
2.5
750
T1
EVDO Rev A
3072
1475
4287
2.9
2812
3xT1
EVDO Rev 0
2458
1311
4137
3.2
2826
3xT1
Figure 2. Actual Downlink Data Rate of 3G Compared to Cisco Accelerated 3G in a Typical 15- to 20-User Remote Office with an HTTP Application Utilizing 100% of Available Bandwidth (Results Are from 18 Concurrent Users Each Generating Three Concurrent TCP Connections)
Cisco NCE supports all TCP-based applications, and similar results are achieved with other application protocols such as FTP and Simple Mail Transfer Protocol (SMTP) as shown in Table 2. Data in Table 2 was collected by simulating the actions of 18 concurrent users each running HTTP and FTP file download applications on the downlink, and an SMTP client sending email on the uplink. The traffic profile was 70 percent HTTP, 20 percent FTP, and 10 percent SMTP. In this scenario, the 3G link bandwidth utilization dropped to approximately 80 percent, a value more likely seen on a busy WAN link. Figure 3 provides graphical depiction of the gain achieved with the Cisco Accelerated 3G solution in comparison to actual performance of a native 3G connection for the mixed-traffic profile.
Table 2. Aggregate Data Rate for 3G and Cisco Accelerated 3G in a Typical 15- to 20-User Remote Office with a Mixed Traffic Profile of 70% HTTP, 20% FTP, and 10% SMTP and Utilizing Approximately 80% of Bandwidth; HTTP and FTP Used Downlink for File Download, and SMTP Used Uplink to Send Email (Results Are from 18 Concurrent Users Each Generating Three Sequential TCP Connections)
3G Standard
3G Theoretical Data Rate (kbps)
3G Actual Data Rate (kbps)
Cisco Accelerated 3G Data Rate (kbps)
Gain Factor (accelerated/
actual)
Bandwidth Increase (kbps)
Wireline Equivalent
EDGE
237
161
573
3.6
412
1/3T1
HSDPA
700
436
1679
3.8
1242
T1
EVDO Rev A
3072
1178
4692
4.0
3514
3xT1
EVDO Rev 0
2458
1007
4598
4.6
3591
3xT1
Figure 3. Actual Aggregate Data Rate of 3G Compared to Cisco Accelerated 3G in a Typical 15- to 20-User Remote Office with a Mixed-Traffic Profile of 70% HTTP, 20% FTP, and 10% SMTP and Utilizing Approximately 80% of Bandwidth; HTTP and FTP Used Downlink for File Download, and SMTP Used Uplink to Send Email (Results Are from 18 Concurrent Users Each Generating Three Sequential TCP Connections)
Cisco Accelerated 3G Solution Performance Test Details
Cisco NCE accelerates WAN-bound traffic by using compression techniques and a variety of TCP protocol optimizations. The primary determinants of performance improvement are available bandwidth, link latency, packet loss rate, compressibility of the data stream, and bandwidth utilization. In the case of 3G, the first three factors are determined by the choice of the 3G CDMA or GSM/UMTS standard used by the 3G service provider. Some variability exists depending on the time of the day, distance or physical obstructions between the 3G antenna and the base transceiver station (BTS), weather, and other environmental factors. These factors for the most part cannot be controlled.
Compressibility of the data stream crossing the WAN link is determined by the application that is sending or receiving the data. To provide generally applicable and consistently reproducible results, the Cisco Accelerated 3G solution was tested with the Standard Canterbury Corpus (http://www.data-compression.info/Corpora/CanterburyCorpus/), which is an industry benchmark for measuring performance of compression. The corpus consists of 11 file types representing typical data that can be directly processed by the user. These files were sent and received by the HTTP and FTP applications. It is important to note that the Canterbury Corpus contains typical user data and only a small amount of data encoded for computer processing with markup languages such as XML or HTML. Data generated for computer processing represents large percentage of typical network traffic, is highly compressible, and therefore the performance gain in a typical scenario would be even greater than presented in Table 1 and Table 2.
Bandwidth utilization influences the effectiveness of TCP optimization techniques. Standard TCP protocol is inefficient in fully utilizing all available bandwidth. The open standard SCTP used by Cisco NCE contains favorable characteristics of TCP as well as UDP combined into a better performing transport protocol. SCTP offers reliability features absent in TCP, and most important, it was designed from the start to overcome performance inefficiencies inherent in TCP. The use of SCTP to encapsulate traffic leads to a significant improvement in bandwidth utilization, as illustrated by the different performance gains in Table 1 and Table 2. Table 1 shows a test scenario in which 18 concurrent users each with three concurrent TCP connections repeatedly download the 11 Canterbury Corpus files. All available bandwidth is fully saturated, and TCP optimization does not have any effect. All the performance gain is achieved from Cisco NCE compression alone. Table 2 shows a typical scenario in which 18 users are downloading the Canterbury Corpus files in a sequential manner, resulting in approximately 80 percent utilization of bandwidth. Here SCTP takes advantage of the extra bandwidth and adds performance improvement beyond compression.
Cisco Accelerated 3G Solution Configuration
The selection of the Cisco 3G WWAN HWIC depends on the set of 3G standards used by the local service provider. The selection of the Cisco NCE model, in general, depends on the Cisco Integrated Services Router platform that will host the module. The AIM-TPO-1 model is appropriate for WAN links with bandwidth less than 4 Mbps and AIM-TPO-2 for WAN links with bandwidth less than 10 Mbps. To reach another location in the enterprise network, traffic sent over a 3G link may eventually be routed over the Internet. It is a security best practice to use VPN technology to protect valuable data traversing the Internet. Various VPN solutions are available in the Cisco IOS Software Advanced Security image. Table 3 summarizes the recommended configurations.
Table 3. Recommended Configuration for Cisco Accelerated 3G Solution
Router
Hardware Configuration
Cisco 3G WWAN HWIC
Cisco NCE Model
Cisco IOS Software
Cisco IOS Software Image
Cisco NCE Software
Cisco 1841
Default
HWIC-3G-CDMA or HWIC-3G-GSM
AIM-TPO-1
Release 12.4(20)T or later
IP Base or Adv Sec (recommended)
Release 1.0.3 or later
Cisco 2800 Series
Default
HWIC-3G-CDMA or HWIC-3G-GSM
AIM-TPO-2
Release 12.4(20)T or later
IP Base or Adv Sec (recommended)
Release 1.0.3 or later
Cisco 3800 Series
Default
HWIC-3G-CDMA or HWIC-3G-GSM
AIM-TPO-2
Release 12.4(20)T or later
IP Base or Adv Sec (recommended)
Release 1.0.3 or later
Configuring 3G WWAN HWIC for Primary Access
Deployment of Cisco Accelerated 3G requires configuration of the Cisco 3G WWAN HWIC and the Cisco NCE service module. This can be accomplished through the CLI commands listed here.
Router(config)# chat-script A3GPROVIDER "" "atdt#777" TIMEOUT 30 "CONNECT" ! Defines command to be sent by the dialer to DCE
Router(config)# line 0/0/0 ! Enters line configuration mode
The PPP connection in the configuration below is between the router and the provider equipment (PE) device, however the IP connection is end to end from the branch router to the central site router.
Router(config)# access-list 1 permit any ! Defines access list that permits all traffic
Router(config)# dialer-list 1 protocol ip list 1 ! Creates dialer list for dialer group 1 that permits access to all traffic
Configuring Cisco 3G WWAN HWIC for Backup with Object Tracking
There are several ways to configure the cellular interface for backup. The following examples show the use of floating static routes with object tracking. Refer to the Cisco 3G WWAN HWIC documentation for additional ways of configuring the Cisco 3G WWAN HWIC for backup.
Router(config)# track 1 interface FastEthernet0/0 ip routing !Enables tracking on the primary WAN interface
Router(config)# ip route 0.0.0.0 0.0.0.0 FastEthernet0/1 track 1 ! Creates a static default route for the primary WAN interface with object tracking
Router(config-if)# ip route 0.0.0.0 0.0.0.0 Cellular0/0/0 200 !Creates a static floating default route for the backup WAN interface with metric higher than the primary interface default route
Configuring the Cisco NCE Service Module in Cisco IOS Software
The Cisco NCE Advanced Interface Module (AIM) is an internal service module. For TCP traffic to be forwarded to the module, the internal backplane link between the service module and the router must be configured, just as with any other routable link. Figure 3 shows a high-level view of the internal connection between Cisco IOS Software and the Cisco NCE service module.
Figure 4. Configuration of Cisco NCE Advanced Integration Module
Router(config)# interface Transport-Opt-Service-Engine0/0 !Enters NCE module configuration mode
Router(config-if)# ip address 10.0.0.1 255.255.255.252 ! Assigns IP address to the router's backplane interface
Router(config-if)# service-module ip address 10.0.0.2 255.255.255.252 ! Assigns IP address to NCE interface
Router(config-if)# service-module ip default-gateway 10.0.0.1 ! Assigns default gateway for the service module
Router(config-if)# exit
Router(config)# ip route 10.0.0.2 255.255.255.255 Transport-Opt-Service-Engine0/0! Sets routing table entry for NCE module
Router(config-if)# transport-opt 2 interface Transport-Opt-Service-Engine0/0 ! Enables NCE traffic interception on the 3G interface and assigns id 2 to the binding
Router(config-if)# exit
If the Cisco 3G WWAN HWIC is used for backup and Cisco NCE is used to provide data rate acceleration both on the primary link and the backup link then Cisco NCE interception must be configured on the primary interface:
Router(config)# interface Serial0/1/0 ! Enters serial interface configuration mode
Router(config-if)# transport-opt 1 interface Transport-Opt-Service-Engine0/0 ! Enables NCE traffic interception on the 3G interface and assigns id 1 to the binding
NCE(config-tpo-id)> default policy-action all ! Enables TCP optimization and compression
NCE(config-tpo-id)> sctp-peer 172.16.0.1 tos 0 ! Configures remote peer address and specifies that all optimized traffic will be marked with IP Type of Service value of 0
NCE(config-tpo-id)> exit
If the Cisco 3G WWAN HWIC is used for backup, Cisco NCE binding must be configured for the primary interface:
NCE(config-tpo-id)> default policy-action all ! Enables TCP optimization and compression
NCE(config-tpo-id)> sctp-peer 172.16.0.2 tos 0 ! Configures remote peer address and specifies that all optimized traffic will be marked with IP Type of Service value of 0
Accelerated 3G performance testing has shown that throughput and application response time improves when the optional bandwidth command is configured on the Cisco NCE module. Peak bandwidth should be set to the maximum bandwidth available on the 3G link, and guaranteed bandwidth to the lowest bandwidth available on the link. The forward-link values should be configured at the central site Cisco NCE module, and the reverse-link values on the branch-office module. Table 4 provides values obtained in Cisco testing. These values were derived from the Speakeasy Speed Test application available at http://www.speakeasy.net/speedtest/. To determine the appropriate peak and guaranteed bandwidth values, run the Speed Test application and multiply the upload and download speeds by 1.1 to get peak reverse and forward data rates respectively. Multiply the upload and download speeds by 0.9 to get the guaranteed reverse and forward data rates respectively.
Table 4. Typical Values for Peak and Guaranteed Bandwidth (Bandwidths Are Average Speeds Observed over Multiple Carrier Networks at Different Times of the Day; Actual Speeds Vary Based on the Number of Active Users, Distance from the BTS, and Signal Strength and Interference)
3G Standard
Downlink Peak Bandwidth
Downlink Guaranteed Bandwidth
Uplink Peak Bandwidth
Uplink Guaranteed Bandwidth
EDGE
171
150
56
52
HSDPA
1750
1600
350
290
EVDO Rev A
1800
1500
1600
1200
EVDO Rev 0
1600
1300
150
133
The Cisco NCE module can be configured at the branch site with the following commands:
NCE(config-tpo-id)>bandwidth 1600 1300 tos 0! Sets peak and guaranteed bandwidth for downlink
Cisco NCE is a symmetric solution that requires termination of optimized traffic flows at a central site that is hosting the remote applications or serving as a gateway to the Internet. The termination is provided by a Cisco NCE aggregation device, which is typically one of the Cisco 3800 Series routers equipped with the Cisco NCE Network Module (NME-TPO). A single Cisco NCE Network Module supports aggregation of traffic from up to 50 sites, and the Cisco 3845 Integrated Services Router can be equipped with up to four Cisco NCE Network Modules, providing aggregation for up to 200 remote sites and branch offices. The Cisco NCE aggregation device can be deployed either in-path or out-of-path. Out-of-path deployment requires a redirection mechanism to be enabled on the device aggregating the WAN traffic. See the Cisco NCE documentation for additional deployment instructions.
Typical Branch Deployment of Cisco Accelerated 3G Solution
A typical branch deployment will use a 3G WWAN connection either for primary access or as a backup link. When a 3G link is used as a backup to a traditional wireline connection, Cisco NCE can also be used to accelerate throughput and remote application response time on the primary link. In case the primary link fails and the router switches over to the 3G backup link, Cisco NCE switches over and continues to accelerate traffic on the 3G link as shown in Figure 4.
Note: When Cisco NCE is configured for interception on both the primary and backup interfaces, each link must have a dedicated peer device that cannot be shared with the other link. Therefore, the head-end aggregation device must have at least two Cisco NCE Network Modules to support a dual primary and backup configuration. However, multiple remote sites with both primary and backup interface interception can share the two aggregation modules, up to the 50-remote-sites limit. This constraint will be removed in future releases of the product.
In the following test scenario, an Ethernet wireline link was configured for primary access and a 3G WWAN link for backup. Cisco NCE was configured to optimize traffic on both the primary and backup links. Initially the traffic was directed over the primary access link. When the primary link was disrupted, the traffic switched to the backup link. After some time, the primary link became active again, and traffic switched away from the backup link. In all cases, Cisco NCE continued to optimize traffic on whichever link was active.
The following section describes a typical branch office and provides a corresponding configuration. Typical services such as firewall, VPN, and multicast were selected to demonstrate the transparency of the Cisco Accelerated 3G solution to other Cisco IOS Software features. Figure 5 provides the topology of the test scenario, and Table 5 lists features that were enabled on the branch-office router. The VPN tunnel configuration is provided.
Figure 5. Deployment Scenario for Primary-to-Backup Switchover Test
Table 5. Features Enabled in the Primary-to-Backup Switchover Test
