Table Of Contents
Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
Information About Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
Lossless Compression Codec on NM-HDV
ATM Cell Switching on AIM-ATM and AIM-ATM-VOICE-30
BITS Clocking on the Cisco 3660 and Cisco 3745
How to Configure Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
Configuring the Cell Site Router for BITS Clocking
Configuring ATM Cell Switching
Configuring the Lossless Compression Codec
Disabling Connection Admission Control
Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
The Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source features introduce a new compression technique in DSP firmware and add enhancements to Cisco IOS that include cell switching on ATM segmentation and reassembly (SAR), and the use of an external BITS clocking source. These features enable Cisco multiservice routers to be used to transparently groom and compress traffic in a wireless service provider network and enable a service provider to optimize the bandwidth used to backhaul the traffic from a cell site to the mobile central office for more efficient use of existing T1 and E1 lines.
Feature Specifications for Cisco Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
Feature History Release Modification12.3(4)XD
These features were introduced.
12.3(7)T
These features were integrated into Cisco IOS Release 12.3(7)T.
Supported PlatformsCisco 3660, Cisco 3745
Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.
Contents
This feature module includes the following sections:
•Information About Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
•How to Configure Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
Prerequisites for Cisco Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
The Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source features require a Cisco 3660 or Cisco 3745 with the following components installed:
Restrictions for Cisco Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
•Operations, administration, and maintenance (OAM) cell insertion is not supported on cell-switched PVCs.
•AIM-ATM and AIM-ATM-VOICE-30 modules support a maximum of four T1/E1s. This can consist of two incoming and two outgoing, or three incoming and one outgoing T1/E1s. An IMA group cannot be split between multiple AIMs.
•Certain combinations of AIM modules can become inoperable when installed in a Cisco 3745. This problem only affects Cisco 3745 routers manufactured before June 11, 2003. See the following field notice for detailed information about this problem:
http://www-tac.cisco.com/Support_Library/field_alerts/fn25194.html
•Voice activity detection (VAD) and echo cancellation are disabled when lossless compression is enabled.
•Lossless compression R1 is supported for VoATM calls with AAL2 and subcell multiplexing. VoIP calls are not supported at this time.
•ATM cell switching is limited to a maximum of 25 connections per AIM-ATM.
•Do not configure more than 29 LLCC channels per NM-HDV module. Configuring more than 29 LLCC channels can cause unreliable operation.
•J1 controller is not supported.
•Traffic policing is not supported.
•For Cisco 3660 routers with two NM-HDV modules installed, do not install the modules in the following slot combinations:
–Slot 1 and Slot 3
–Slot 2 and Slot 4
–Slot 5 and Slot 6
Using these slot combinations can result in packet loss.
Information About Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
The Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source features work together to groom and compress T1 and E1 traffic between cell sites and a mobile central office. These features require a Cisco 3660 or Cisco 3745 router to be installed at the base transceiver station (BTS). This cell site router performs ATM switching and compression of cell site traffic for transport to the base station controller (BSC). A Cisco MGX 8850 with AUSM and VISM-PR terminates the T1/E1 lines that carry lossless compression codec (LLCC) traffic, converting the traffic back to PCM before passing it to the BSC. Figure 9 shows a sample topology that makes use of the Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source features.
Figure 9 Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source Features
Lossless Compression Codec on NM-HDV
The Lossless Compression R1 feature introduces a new compression technique in DSP firmware and the VISM card— the lossless compression codec (LLCC). LLCC operates in a similar fashion to the existing clear channel codec: the decoded 64kbps PCM stream is a bit-exact replica of the PCM stream provided on the TDM side of the encoding DSP. However, rather than simply packetizing the PCM stream, the LLCC encoder applies a lossless data compression scheme. This results in a net reduction in the data transmission rate, yielding a reduction in the packet transmission rate.
ATM Cell Switching on AIM-ATM and AIM-ATM-VOICE-30
The Cisco ATM Cell Switching feature enables the router to perform cell switching between two ATM connections on AIM-ATM and AIM-ATM-VOICE-30 cards, giving the router the ability to receive ATM traffic from the BTS and backhaul it to the mobile central office.
BITS Clocking on the Cisco 3660 and Cisco 3745
BITS (Building Integrated Timing Supply) network clocking enables a Cisco 3660 or Cisco 3745 router to derive network timing from the central office. BITS must be configured on the cell site router to support this feature.
How to Configure Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source
The procedures for configuring the Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source features require the following tasks:
•Configuring the Cell Site Router for BITS Clocking
•Configuring ATM Cell Switching
•Configuring the Lossless Compression Codec
•Disabling Connection Admission Control
The instructions that follow refer to the sample configuration shown in Figure 10. With this configuration, the cell site router supports three E1 connections to the BTS. Compressed cellular traffic is transported to the BSC (by way of the Cisco MGX 8850) over the E1 1/0 and E1 1/1 interfaces. Additionally, BITS clocking is derived from E1 1/1.
Figure 10 Sample Configuration
Configuring the Cell Site Router for BITS Clocking
BITS clocking enables the router at a cell site to derive timing from the mobile central office. BITS clocking ensures that data flows to a single network clock source, preventing mismatches and data slips in traffic between the BTS and the BSC. The procedure that follows configures the AIM to receive BITS clocking from E1 1/1 controller.
Summary Steps
1. enable
2. configure terminal
3. network-clock-participate slot number
4. network-clock-select priority slot number
5. controller e1 slot/port
6. clock source {line [primary | bits] | internal}
Detailed Steps
Configuring ATM Cell Switching
The procedure that follows configures the cell site router to switch ATM traffic with the Cisco MGX 8850 at the BSC. This procedure configures ATM switching between E1 3/0 and E1 1/0, using the AIM installed in Slot 1.
Summary Steps
1. enable
2. configure terminal
3. network-clock-participate slot number
4. network-clock-participate slot number
5. network-clock-participate aim number
6. controller t1 | e1 slot/port
7. mode atm aim aim-slot
8. controller t1 | e1 slot/port
9. mode atm aim aim-slot
10. interface atm interface-number/subinterface-number
11. pvc vpi/vci l2transport
12. interface atm interface-number/subinterface-number
13. pvc vpi/vci l2transport
14. connect id atm slot/port-1 atm slot/port-2
Detailed Steps
Configuring the Lossless Compression Codec
The procedure that follows configures an LLCC voice channel on E1 4/0 and sends it over the ATM network using E1 1/0 and the AIM installed in Slot 1.
Summary Steps
1. enable
2. configure terminal
3. network-clock-participate slot number
4. network-clock-participate slot number
5. network-clock-participate aim number
6. voice service {pots | voatm | vofr | voip}
7. session protocol aal2
8. subcell-mux
9. codec aal2-profile custom profile-number codec
10. controller t1 | e1 slot/port
11. mode atm aim aim-slot
12. controller t1 | e1 slot/port
13. ds0-group ds0-group-number timeslots timeslot-list type signaling method
14. interface atm interface-number/subinterface-number
15. pvc vpi/vci
16. vbr-rt peak-rate average-rate burst
17. encapsulation aal2
18. dial-peer voice tag voatm
19. destination-pattern string
20. session protocol aal2-trunk
21. session target interface pvc vpi/vci
22. signal-type cas | cept | ext-signal | transparent
23. codec aal2-profile custom profile-number codec
24. voice-port {slot-number/subunit-number/port | slot/port:ds0-group-no}
25. playout-delay {fax | maximum | nominal} milliseconds
26. connection {plar | tie-line | plar-opx} digits | {trunk digits [answer-mode]}
Detailed Steps
Note To ensure that the voice-port configuration takes affect, issue the shutdown command, followed by no shutdown to enable it again.
Disabling Connection Admission Control
Connection admission control (CAC) is a set of actions taken by each ATM switch during connection setup to determine whether the requested QoS will violate the QoS guarantees for established connections. CAC reserves bandwidth for voice calls, however, the bandwidth required when LLCC is used is dynamic and usually less than what is generally reserved by CAC. Disabling CAC may help in better utilization of bandwidth when LLCC is used. The procedure that follows disables CAC.
Summary Steps
1. enable
2. configure terminal
3. interface atm interface-number/subinterface-number
4. pvc vpi/vci
5. cac_off
Detailed Steps
Verifying Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source Configuration
This section provides a set of show commands you can use to verify the configuration of the Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source features. It includes the following commands:
•show voice trunk supervisory summary
show connection all
The following example shows output from the show connection all command. In this example, Switched-Conn is a cell-switched connection established between PVC 10/110 and PVC 30/130, which are configured under ATM1/0 and ATM3/0 respectively.
Router# show connection allID Name Segment 1 Segment 2 State========================================================================3 V-100-700 E1 1/0(VOICE) 00 DSP 07/00/00 UP4 V-120-700 E1 1/2(VOICE) 00 DSP 07/00/00 UP5 Switched-Conn ATM1/0 10/110 ATM3/0 30/130 UPThe show connection all command displays the state of Switched-Conn. If it is in the UP state, then it means the ATM cell switching connection is operational.
show voice dsp
The following example shows output from the show voice dsp command:
Router# show voice dspDSP DSP DSPWARE CURR BOOT PAK TX/RXTYPE NUM CH CODEC VERSION STATE STATE RST AI VOICEPORT TS ABORT PACK COUNT==== === == ======== ======= ===== ======= === == ========= == ===== ==========C549 000 04 llcc 4.3.392 busy idle 0 4/0:0 04 0 1752/1752The show voice dsp command shows if the LLCC codec has been applied to the voice port. Additionally, the TX/RX COUNT indicates if packet exchange is occurring. If LLCC is operational, then TX/RX COUNT will display similar values.
show voice call port-id
The show voice call command gives detailed information about the lossless compression codec. The following example shows output from the show voice call command:
Note The show voice call command has a limitation that causes it to display invalid values. To ensure that accurate values are reported, invoke this command twice and look at the second output.
Router# show voice call 4/0:04/0:0 1vtsp level 0 state = S_CONNECTvpm level 1 state = S_TRUNKEDvpm level 0 state = S_UPlossless compression summary:average compression ratio since reset = 50current compression ratio = 50max buffer size (ms) = 41nominal buffer size (ms) = 25current buffer size (ms) = 26total encoder input frame count = 5534total encoder output frame count = 2767encoded tx front-end compressed frame count = 2767encoded tx back-end compressed frame count = 0encoded tx frame count (no compression) = 0underflow error count = 0overflow error count = 0decode error count = 0tx signalling frame count = 11rx signalling frame count = 10rx bad checksum frame count = 0rx good checksum frame count = 2777show voice trunk supervisory summary
The following example shows output from the show voice trunk supervisory summary command:
Router# show voice trunk supervisory summarySLOW SCAN4/0:0(1) : state : TRUNK_SC_CCS_CONNECT, mastershow interfaces
The following example shows output from the show interfaces command:
Router# show interfaces atm1/0ATM1/0 is up, line protocol is upHardware is ATM AIM E1MTU 4470 bytes, sub MTU 4470, BW 1920 Kbit, DLY 20000 usec,reliability 0/255, txload 1/255, rxload 1/255Encapsulation ATM, loopback not setEncapsulation(s): AAL5255 maximum active VCs, 256 VCs per VP, 0 current VCCsVC Auto Creation Disabled.VC idle disconnect time: 300 secondsLast input never, output never, output hang neverLast clearing of "show interface" counters neverInput queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0Queueing strategy: Per VC Queueing30 second input rate 0 bits/sec, 0 packets/sec30 second output rate 0 bits/sec, 0 packets/sec0 packets input, 0 bytes, 0 no bufferReceived 0 broadcasts, 0 runts, 0 giants, 0 throttles0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort0 packets output, 0 bytes, 0 underruns0 output errors, 0 collisions, 1 interface resets0 output buffer failures, 0 output buffers swapped outAdditional References
For additional information related to the Cisco Lossless Compression R1, ATM Cell Switching, and External BITS Clocking Source feature, refer to the following references:
Related Documents
Related Topic Document TitleConfiguring voice features
Configuring ATM advanced integration modules
AIM-ATM and AIM-ATM-VOICE-30 on the Cisco 2600 Series, Cisco 3660, and Cisco 3700 Series
Configuring high-density voice network modules
Standards
Standards 1 TitleNo new standards are supported by this feature.
1 Not all supported standards are listed.
MIBs
RFCs
Technical Assistance
Command Reference
The following new and modified commands are pertinent to this feature. To see the command pages for these commands and other commands used with this feature, go to the Cisco IOS Master Commands List, Release 12.4, at http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124mindx/
124index.htm.•cac_off
•clock source (T1/E1 controller)
•codec aal2-profile
•connect (atm)
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