Cisco 827 Router Frequently Asked Questions

A. H.323 is an International Telecommunication Union (ITU-T) standard that describes the architecture for interactive multimedia communication over a packet-based network. An H.323 Gateway allows non-H.323 devices, such as analog phones and faxes, to make calls using the H.323 protocol suite. The Cisco 827 is an H.323 gateway.

The H.323 Gatekeeper keeps track of the addresses or services associated with a particular gateway.

Q. What are the voice bandwidth requirements for different codecs?

A. Voice bandwidth requirements are:

G.711 – 106 Kbps (50 pps, 200 byte long packets)

G.729 – 44 Kbps (34 pps, 60 byte long packets) (default)

G.723 – 30 Kbps (34 pps, 64 byte long packets)

For more information, refer to Voice over IP - Per Call Bandwidth Consumption.

Q. Which ATM classes of traffic should I use for voice?

A. Four ATM classes of traffic can be configured on a PVC:

Constant Bit Rate: cbr pcr

Real-time Variable Bit Rate: vbr-rt pcr scr bs

Non real-time Variable Bit Rate: vbr-nrt pcr scr bs

Unspecified Bit Rate: ubr pcr

For a PVC with voice traffic, vbr-rt should be used. Configure scr to be at least four times the particular codec's bandwidth requirement when the four voice ports are used. (See What are the voice bandwidth requirements for different codec?).

For example, if you have a 640 Kbps upstream PVC that runs codec G.729, you can configure the PVC with scr to be equal to 176.

Q. How do I troubleshoot an ADSL problem with the Cisco 827?

A. First, check the CD LED on the front panel. It is off when the ADSL carrier is not detected. If the carrier is not detected, it is likely a physical problem due to a bad cable or a problem with the ADSL line or WAN service.

Make sure the ATM0 interface is not administratively shut down and the cable is good (the Cisco 827 uses pin 3 and pin 4 of the ADSL cable). The ADSL cable that you connect to the Cisco 827 router must be unshielded twisted-pair (UTP) cords. The use of a regular telephone cable can introduce line errors. After that, contact your ADSL line or service provider to determine if there is a problem.

If show interface atm 0 shows "up/down", it means the Cisco 827 sees the ADSL carrier but cannot train up with the Digital Subscriber Line Access Multiplexer (DSLAM) at the central office (CO).

Turn on debug atm events (you need to turn on terminal monitor if you are in a Telnet session to the router) and look at the outputs:

The normal activation state changes are as follows:
STOP		in shutdown state
INIT		initialization
DLOAD_1		init and downloading 1st image
DLOAD_2		downloading 2nd image
DO_OPEN		requesting activation with CO
SHOWTIME	activation succeeded 
When in the DO_OPEN state, look for the Modem state for the progress information:
Modem state = 0x0	modem down
Modem state = 0x8	modem waiting to hear from CO
Modem state = 0x10	modem heard from CO, now training
Modem state = 0x20	activation completed and link goes up
This is sample debug output:
*Mar  1 00:08:21.771: DSL: SM: [DMTDSL_DO_OPEN -> DMTDSL_INIT]
*Mar  1 00:08:23.771: DSL: SM: [DMTDSL_INIT -> DMTDSL_DLOAD_1]
*Mar  1 00:08:23.771: DSL: Downloading asw_init_2_5_8.bin
*Mar  1 00:08:23.771: DSL: Downloaded 2 blocks... Finished!
*Mar  1 00:08:23.775: DSL: Sent command 0x14
*Mar  1 00:08:26.275: DSL: Received 1 timer events during wait
*Mar  1 00:08:27.711: DSL: Received response: 0x80
*Mar  1 00:08:27.715: DSL: SM: [DMTDSL_DLOAD_1 -> DMTDSL_DLOAD_2]
*Mar  1 00:08:27.715: DSL: Downloading asw_r2_5_8.bin
*Mar  1 00:08:27.791: DSL: Downloaded 100 blocks
*Mar  1 00:08:27.863: DSL: Downloaded 200 blocks
*Mar  1 00:08:27.935: DSL: Downloaded 300 blocks
*Mar  1 00:08:27.975: DSL: Downloaded 354 blocks... Finished!
*Mar  1 00:08:27.975: DSL: Sent command 0x14
*Mar  1 00:08:29.991: DSL: SM: [DMTDSL_DLOAD_2 -> DMTDSL_DO_OPEN]
*Mar  1 00:08:29.991: DSL: Send ADSL_OPEN command.
*Mar  1 00:08:29.991: DSL: Using subfunction 0x2
*Mar  1 00:08:29.991: DSL: Sent command 0x3
*Mar  1 00:08:32.491: DSL: 1: Modem state = 0x8
*Mar  1 00:08:34.991: DSL: 2: Modem state = 0x8
*Mar  1 00:08:37.491: DSL: 3: Modem state = 0x10
*Mar  1 00:08:39.991: DSL: 4: Modem state = 0x10
*Mar  1 00:08:42.491: DSL: 5: Modem state = 0x10
*Mar  1 00:08:44.991: DSL: 6: Modem state = 0x10
*Mar  1 00:08:46.003: DSL: Received response: 0x24
*Mar  1 00:08:46.003: DSL: Showtime!
*Mar  1 00:08:46.007: DSL: Sent command 0x11
*Mar  1 00:08:46.011: DSL: Received response: 0x61
*Mar  1 00:08:46.011: DSL: Read firmware revision 0x1A04
*Mar  1 00:08:46.011: DSL: SM: [DMTDSL_DO_OPEN -> DMTDSL_SHOWTIME]

Q. How can I check the downstream and the upstream speed trained up with?

A. You can issue a show controller [atm 0 | begin chip] to display the ADSL status information. This is sample output of the command:

DSL-827# show controller atm 0 | begin chip
Alcatel 20140 chipset information
                ATU-R (DS)                      ATU-C (US)
Modem status:    Showtime (DMTDSL_SHOWTIME)
ANSI Issue/rev:  2/1                             8/18
Vendor ID:       0x0022                          0x0046
Capacity Used:   12%                             21%
Noise Margin:    35.5 dB                         31.0 dB
Output Power:    10.5 dBm                        20.0 dBm
Attenuation:     12.0 dB                          1.0 dB
Defect Status:   None                            None                        
Last Fail Code:  None
Selftest Result: 0x10
Subfunction:     0x02
Interrupts:      359 (1 spurious)
Activations:     1
SW Version:      2.58
FW Version:      0x1A04
 
                 Interleave        Fast    Interleave              Fast
Speed (kbps):           640           0           128                 0
Reed-Solomon EC:          0           0             0                 0
CRC Errors:               0           0             1                 0
Header Errors:            0           0             0                 0
Bit Errors:               0           0
BER Valid sec:            0           0
BER Invalid sec:          0           0
 
DMT Bits Per Bin
00: 0 0 0 0 0 0 0 0 0 0 2 2 2 3 3 4
10: 0 4 3 4 4 4 3 3 3 2 2 0 0 0 0 0
20: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
30: 0 0 0 0 0 0 0 2 2 2 2 2 2 2 0 2
40: 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
50: 2 2 2 2 2 2 2 2 2 2 2 2 0 0 2 2
60: 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
70: 2 2 2 2 2 2 0 0 2 2 2 2 0 2 2 2
80: 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
90: 2 2 2 2 2 2 2 2 2 2 2 0 2 2 2 2
A0: 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
B0: 2 2 2 2 2 2 2 2 2 2 0 2 2 2 2 2
C0: 2 2 2 2 2 2 2 2 0 2 2 2 2 2 2 0
D0: 2 2 2 2 0 2 2 0 0 0 0 0 0 0 0 0
E0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
F0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Q. How can I identify the Cisco IOS® Software release that I am running?

A. To learn the Cisco IOS Software release that runs on your Cisco 827, log in to the Cisco 827, type show version, and then press Enter. The software version is displayed. For example:

IOS (tm) C820 Software (C820-SY6-M), Version 12.2(1)XD1

This example shows output from a show version command.

Router> show version
Cisco Internetwork Operating System Software 
IOS (tm) C820 Software (C820-SY6-M), Version 12.2(1)XD1, 
EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)
Synched to technology version 12.2(0.11)T
TAC:Home:SW:IOS:Specials for info
Copyright (c) 1986-2001 by cisco Systems, Inc.
Compiled Wed 30-May-01 20:05 by ealyon
Image text-base: 0x80013170, data-base: 0x806E2DF0
 
ROM: System Bootstrap, Version 12.1(1r)XB1, RELEASE SOFTWARE (fc1)
ROM: C820 Software (C820-SY6-M), Version 12.2(1)XD1, 
EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)
 
Router uptime is 2 days, 16 minutes
System returned to ROM by power-on
System image file is "flash:c820-sy6-mz.122-1.xd1.bin..bi"
 
CISCO C827-4V (MPC855T) processor (revision 0x501) with 
31744K/1024K bytes of memory.
Processor board ID JAD04140IX7 (1851984093), with hardware revision 1987
CPU rev number 5
Bridging software.
1 Ethernet/IEEE 802.3 interface(s)
1 ATM network interface(s)
128K bytes of non-volatile configuration memory.
8192K bytes of processor board System flash (Read/Write)
2048K bytes of processor board Web flash (Read/Write)
 
Configuration register is 0x2102

Q. Where can I get the latest software upgrade for the Cisco 827?

A. You can download the latest software upgrade from the Cisco Software Center ( registered customers only) .

Q. How do I upgrade the Cisco IOS Software on my Cisco 827?

A. Refer to Upgrading Cisco IOS Software for the Cisco 806, 826, 827, 828, and SOHO70 Routers.

Q. How can I recover my password on a Cisco 827?

A. Refer to Password Recovery Procedure for the Cisco 806, 827, and 837 Series Routers.

Q. How do I troubleshoot Layer 1 problems on a Cisco 827?

A. Refer to Troubleshooting Layer 1 on a Cisco 827 Router.

Q. Does the Cisco 827 support ANSI ADSL DMT issue 2, G.DMT, and G.LITE line encoding?

A. Yes, the Cisco 827 supports ANSI ADSL DMT issue 2, G.DMT, and G.LITE line encoding methods. It is recommended that you use Cisco IOS Software Release 12.1(5)YB4 or later for full support of line encoding methods.

Note: The Cisco 827 ADSL interface is in auto detect mode by default and auto detects the line encoding to use when it connects to your Internet Service Provide (ISP).
1)  ansi-dmt            ANSI full rate mode        *ANSI T1.413 Issue 2 
2)  itu-dmt             ITU full rate mode         *ITU G.992.1 (G.dmt) 
3)  splitterless        G.lite mode                *ITU G.992.2 (G.lite) 
4)  auto                auto detect mode

Q. What are the software and hardware requirements to run ANSI ADSL DMT issue 2, G.DMT, and G.LITE line encoding on a Cisco 827?

A. Cisco IOS Software Release 12.1(5)YB4 or later is required for full support of line encoding methods.

Also, you must properly configure line encoding on the Cisco 827 ADSL interface. This interface is in auto detect mode by default and auto detects the line encoding to use when it connects to your ISP. If you choose to configure a line encoding method, contact your ISP to find out the type of encoding to use.

Q. How do I connect my PC to the console port of the Cisco 827?

A. Refer to the Installation section of the Cisco 827 Routers Hardware Installation Guide, and the Configuring the Router from a PC section of Cisco IOS Basic Skills.

Q. Where can I learn more about Cisco IOS Software releases and the features they support?

A. Refer to Cisco 800 Series Routers.

Q. Where can I find information about queuing and ATM traffic shaping for the Cisco 827?

A. Refer to Queuing and ATM Traffic Shaping on the Cisco 827 Router.

Q. Where can I find all the sample configurations for the Cisco 827?

A. Refer to Cisco DSL Router Configuration and Troubleshooting Guide.

Q. Where can I find DSL product and security field notices?

A. Refer to DSL/Aggregation Field Notices.

Q. Where can I learn more about using POTS splitters and microfilters in a DSL environment?

A. Refer to Using POTS Splitters and Microfilters in a DSL Environment.

Q. Where can I find information about DSL modem/CPE interface pinouts and status LED descriptions?

A. Refer to DSL Modem/Router Interface Pinouts and Status LED Descriptions.

Q. Where can I find Cisco 827 Router Software and Hardware Configuration Guides?

A. Refer to Cisco 827 Routers and Cisco SOHO 77 Routers.

Q. Where can I find white papers about DSL technology?

A. Refer to the DSL Technical Support page.

Related Information

Contributed by Cisco Engineers