The types of router chassis described in this section demonstrate how VNMs, VICs, and additional voice port adapters are installed on the various platforms. We chose a sampling of Cisco routers to structure our discussion, but the concepts and processes are similar for all Cisco routers, with a few minor adjustments.
E-1/T-1 Voice Connectivity
Digital E-1 and T-1 connectivity allows Cisco series routers and switches to provide E-1 or T-1 voice connectivity to PBXs or to a CO. T-1 voice connections are available for various routers and switches, including, but not limited to Cisco 1700, 2600, 3600, 3700, MC3810, 7200, 7500, AS5300, AS5800, and Catalyst 4000 and 6000 series equipment.
The 1700, 2600, 3600, 7200, and 7500 series routers are capable of VoFR and VoIP. The MC3810 (now end of sale) supports VoFR, VoATM, and VoIP. The AS5300 is able to perform VoIP, VoHDLC, or VoFR functions.
The 7200, 7500 series, and AS5300 series are primarily used as tandem switch points from T-1 tie lines to PBXs and the PSTN to the internal IP network. An example of the use of tandem switch points is receiving a voice call on one VoIP interface and switching it back out another VoIP interface to its final destination. The 1700, 2600, and 3600 routers series can perform this function because support for voice T-1/E-1 interfaces with up to two T-1/E-1 circuits per card has been added. The T-1/E-1 enhanced voice port adapter is used in the 7200 and 7500 series routers and can support up to two T-1s per card. The AS5300 series access switch uses the T-1 carrier card that can support up to four T-1s.
The 7200, 7500, and AS5850 can terminate T-1s for voice traffic into the WAN and forward the signals and transmissions to the 1700, 2600, 3600, and AS5300 series routers for complete processing. The 7200 Series offers a four- or six-slot configuration, with interfaces including ATM, Synchronous Optical Network Technologies (SONET), ISDN BRI, ISDN PRI, T-1, E-1, T3, and E3. Its multi-service interchange (MIX) allows the 7200 to support digital voice as well as gateway functionality through the use of two different trunk interfaces, the high-capacity and medium-capacity T-1/E-1 trunk interface cards. The primary difference between the two cards is that the high-capacity card includes an on-board DSP card for compression. The 7200 Series can support up to 120 voice calls, depending on the module configuration used. This router also supports analog voice applications through the use of voice interface cards (VICs).
1700 Series Router Configurations
The 1700 series modular access routers are designed for small- to medium-sized businesses. The 1700 family has several chassis for different applications, but the two that were designed specifically for voice applications are the 1751 and the 1760. These two modular chassis use the Cisco IOS along with various VICs to support analog and digital voice traffic over the IP network.
Cisco 1751 Modular Access Router
The Cisco 1751 is a standalone chassis that can support up to three voice interface slots. It comes in two models: a base model suited primarily for data, but with an easy upgrade path to voice, and a multiservice model (identified with a V) that includes all features for immediate integration of data and voice. Both models include three slots for data/voice interface cards as well as a 10/100 Ethernet port, a console port, and an auxiliary port. The 1700 series VICs are interchangeable with the Cisco 2600 and 3600 series routers.
The Cisco 1751 includes one PVDM-256K-4 (one DSP) that supports one analog VIC. If two analog VICs or one or more digital ISDN VICs are used, additional DSPs are required. The Cisco 1751 has two DSP slots to support additional voice channels. A PVDM is required to support VICs on the Cisco 1750 and 1760 routers. These two chassis require PVDMs to be placed on the motherboard, unlike the Cisco 2600, 3600, and 3700 routers, which have DSP support on the VNMs.
The Cisco 1760 Modular Access Router
The Cisco 1760 has four slots for VICs, and is available in two models. The base model is suited for data networking, but can be upgraded to support voice. The multi-service model (identified with a V) includes all features for immediate integration of data and voice. Both models include four slots for data/voice interface cards and a 10/100 Ethernet port.
The Cisco 1760 includes one PVDM-256K-4 (one DSP) that supports one analog VIC. If two analog VICs or one or more digital ISDN VICs are used, additional DSPs are required. The Cisco 1760 has two DSP slots to support additional voice channels.
3600 and 3700 Series Router Configurations
Cisco's 3600 and 3700 series routers come in a variety of base configurations that differ in the amount and/or type of standard network interfaces (RJ-45 ports, serial ports, and ISDN ports) that are available. The Cisco3600 and 3700 are designed primarily for traditional and power branch office solutions.
The 3600 series router comes in three varieties: the 3620, which has two network module slots; the 3640, which has four network module slots; and the 3660, which is equipped with six network module slots. The 3640 is end of sale as of this writing.
The 3700 series router comes in two varieties: the 3725, which has three integrated WIC slots and two network module slots, and the 3745, which has three integrated WIC slots and four network module slots. Currently, the built-in WICs do not support VICs.
Most Cisco 1700 VICs can be used for the 3600 and 3700 series except that a VNM is required in these higher-end routers.
| Note | For 3700 platforms, the minimum IOS release is IOS 12.2(8) T for all network modules and VICs. |
7500 Series Router Configurations
The 7500 series high-end routers support voice, video, and data. The Cisco 7500 series includes the Cisco 7505, the Cisco 7507, and the Cisco 7513 with 5, 7, and 13 slots, respectively. Cisco 7500 adapters include the two-port T-1 and E-1 high-capacity enhanced digital voice port adapter, the two-port T-1 and E-1 moderate-capacity enhanced digital voice port adapter, and the one-port T-1 and E-1 enhanced digital voice port adapters.
AS5350 and 5850 Universal Gateway Configuration
The Cisco AS5350 and AS5850 universal gateways provide from 2 to 96 T-1s or E-1s to support data, voice, wireless, and fax services on any port. The AS5350 is only one rack unit high and supports 216 voice, dial, or universal ports. The AS5350 is mainly intended for ISPs and enterprises, whereas the Cisco AS5850 was designed for large service providers. The AS5850 is 14 rack units high and supports 2688 voice or universal ports. Both chassis support hot-swappable cards and fans to minimize service interruption. The AS5350 supports two-, four-, or eight-T-1/E-1 configurations; the AS5850 supports up to four 24-port T-1 cards for a total of 96 T-1s.
| Note | The minimum IOS release for the Cisco AS5850 platform is IOS 12.2(1)XB for the 24-channel T-1 card. |
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