Cisco Router 826 Routers Software Configuration Guide

							  
B-5
Cisco 826, 827, 828, 831, 836, and 837 and Cisco SOHO 76, 77, 78, 91, 96, and 97 Routers Software Configuration Guide
78-14565-03
Appendix B      ROM Monitor
Disaster Recovery with TFTP Download
Optional Variables
These variables can be set with these commands before using the tftpdnld command:
Using the TFTP Download Command
The steps described in this section should be performed while in ROM monitor mode.
Step 1Use the appropriate commands to enter all the required variables and any optional variables described 
earlier in this section.
Step 2Enter the tftpdnld command as follows:
rommon 1 > tftpdnld -r 
NoteThe -r variable is optional. Entering this variable downloads and boots the new software but does 
not save the software to Flash memory. You can then use the image that is in Flash memory the 
next time you enter the reload command. Variable Command
Configures how the router displays file 
download progress.
0—No progress is displayed.
1—Exclamation points (!!!) are displayed to 
indicate file download progress. This is the 
default setting.
2—Detailed progress is displayed during the 
file download process; for example:
Initializing interface.
Interface link state up.
ARPing for 1.4.0.1
ARP reply for 1.4.0.1 received.  MAC 
address 00:00:0c:07:ac:01TFTP_VERBOSE= setting
Number of times the router attempts ARP and 
TFTP download. The default is 7. TFTP_RETRY_COUNT= 
retry_times
Amount of time, in seconds, before the 
download process times out. The default is 
2,400 seconds (40 minutes).TFTP_TIMEOUT= time
Whether or not the router performs a checksum 
test on the downloaded image:
1—Checksum test is performed.
0—No checksum test is performed.TFTP_CHECKSUM=setting 
						

							  
B-6
Cisco 826, 827, 828, 831, 836, and 837 and Cisco SOHO 76, 77, 78, 91, 96, and 97 Routers Software Configuration Guide
78-14565-03
Appendix B      ROM Monitor
Configuration Register
You will see output similar to the following:
IP_ADDRESS: 1.3.6.7
      IP_SUBNET_MASK: 255.255.0.0
     DEFAULT_GATEWAY: 1.3.0.1
         TFTP_SERVER: 223.255.254.254
           TFTP_FILE: c806-sy-mz
Invoke this command for disaster recovery only.
WARNING: all existing data in all partitions on flash will be lost!
Do you wish to continue? y/n:  [n]:
Step 3If you are sure that you want to continue, enter y in response to the question in the output:
Do you wish to continue? y/n:  [n]:y
The router begins to download the new file.
Enter Ctrl-C or Break to stop the transfer before the Flash memory is erased.
Configuration Register
The virtual configuration register is in nonvolatile RAM (NVRAM) and has the same functionality as 
other Cisco routers. You can view or modify the virtual configuration register from either the ROM 
monitor or the operating system software. Within ROM monitor, you can change the configuration 
register by entering the register value in hexadecimal format, or by allowing the ROM monitor to prompt 
you for the setting of each bit.
Changing the Configuration Register Manually
To change the virtual configuration register from the ROM monitor manually, enter the command 
confreg followed by the new value of the register in hexadecimal, as shown in the following example:
rommon 1 > confreg 0x2101
You must reset or power cycle for new config to take effect
rommon 2 >
The value is always interpreted as hexadecimal. The new virtual configuration register value is written 
into NVRAM but does not take effect until you reset or reboot the router.
Changing the Configuration Register Using Prompts
Entering confreg without an argument displays the contents of the virtual configuration register and a 
prompt to alter the contents by describing the meaning of each bit. 
In either case, the new virtual configuration register value is written into NVRAM but does not take 
effect until you reset or reboot the router. 
						

							  
B-7
Cisco 826, 827, 828, 831, 836, and 837 and Cisco SOHO 76, 77, 78, 91, 96, and 97 Routers Software Configuration Guide
78-14565-03
Appendix B      ROM Monitor
Console Download
The following display shows an example of entering the confreg command:
rommon 7> confreg
 
     Configuration Summary
enabled are:
console baud: 9600
boot: the ROM Monitor
 
do you wish to change the configuration? y/n  [n]:  y
enable  “diagnostic mode”? y/n  [n]:  y
enable  “use net in IP bcast address”? y/n  [n]:  
enable  “load rom after netboot fails”? y/n  [n]:  
enable  “use all zero broadcast”? y/n  [n]:  
enable  “break/abort has effect”? y/n  [n]:  
enable  “ignore system config info”? y/n  [n]:  
change console baud rate? y/n  [n]:  y
enter rate: 0 = 9600, 1 = 4800, 2 = 1200, 3 = 2400  [0]:  0
change the boot characteristics? y/n  [n]:  y
enter to boot:
 0 = ROM Monitor
 1 = the boot helper image
 2-15 = boot system
    [0]:  0
 
Configuration Summary
enabled are:
diagnostic mode
console baud: 9600
boot: the ROM Monitor
 
do you wish to change the configuration? y/n  [n]:  
 
 
You must reset or power cycle for new config to take effect
Console Download
You can use console download, a ROM monitor function, to download over the router console port either 
a software image or a configuration file. After download, the file is either saved to the mini-Flash 
memory module or to main memory for execution (image files only).
Use console download when you do not have access to a Trivial File Transfer Protocol (TFTP) server.
NoteIf you want to download a software image or a configuration file to the router over the console port, you 
must use the ROM monitor command.
Note If you are using a PC to download a Cisco IOS image over the router console port at 115,200 bps, ensure 
that the PC serial port is using a 16550 universal asynchronous transmitter/receiver (UART). If the PC 
serial port is not using a 16550 UART, we recommend using a speed of 38,400 or less when downloading 
a Cisco IOS image over the console port. 
						

							  
B-8
Cisco 826, 827, 828, 831, 836, and 837 and Cisco SOHO 76, 77, 78, 91, 96, and 97 Routers Software Configuration Guide
78-14565-03
Appendix B      ROM Monitor
Console Download
Command Description
The following are the syntax and descriptions for the xmodem console download command:
xmodem [-cyrx] destination_file_name
Follow these steps to run Xmodem:
Step 1Move the image file to the local drive where the Xmodem will execute.
Step 2Enter the xmodem command.
Error Reporting
Because the ROM monitor console download uses the console to perform the data transfer, error 
messages are only displayed on the console when the data transfer is terminated. 
If an error does occur during a data transfer, the transfer is terminated, and an error message is displayed. 
If you have changed the baud rate from the default rate, the error message is followed by a message 
telling you to restore the terminal to the baud rate specified in the configuration register. cOptional. Performs the download using 16-bit cyclic 
redundancy check (CRC-16) error checking to validate 
packets. Default is 8-bit CRC.
yOptional. Sets the router to perform the download using 
Ymodem protocol. Default is Xmodem protocol. The 
protocols differ as follows:
Xmodem supports a 128-block transfer size. Ymodem 
supports a 1024-block transfer size.
Ymodem uses (CRC)-16 error checking to validate each 
packet. Depending on the device that the software is being 
downloaded from, this function might not be supported by 
Xmodem.
rOptional. Image is loaded into DRAM for execution. Default 
is to load the image into Flash memory.
xOptional. Image is loaded into DRAM without being executed.
destination_
file_nameThe name of the system image file or the system configuration 
file. In order for the router to recognize it, the name of the 
configuration file must be router_confg. 
						

							  
B-9
Cisco 826, 827, 828, 831, 836, and 837 and Cisco SOHO 76, 77, 78, 91, 96, and 97 Routers Software Configuration Guide
78-14565-03
Appendix B      ROM Monitor
Debug Commands
Debug Commands
Most ROM monitor debugging commands are functional only when Cisco IOS software has crashed or 
is halted. If you enter a debugging command and Cisco IOS crash information is not available, you see 
the following error message:
xxx: kernel context state is invalid, can not proceed.
The following are ROM monitor debugging commands:
stack or k—produces a stack trace; for example:
rommon 6> stack
Stack trace:
PC = 0x801111b0
Frame 00: FP = 0x80005ea8    PC = 0x801111b0
Frame 01: FP = 0x80005eb4    PC = 0x80113694
Frame 02: FP = 0x80005f74    PC = 0x8010eb44
Frame 03: FP = 0x80005f9c    PC = 0x80008118
Frame 04: FP = 0x80005fac    PC = 0x80008064
Frame 05: FP = 0x80005fc4    PC = 0xfff03d70
context—displays processor context; for example:
rommon 7> context
CPU context of the most recent exception:
PC  = 0x801111b0  MSR = 0x00009032  CR  = 0x53000035  LR    = 0x80113694
CTR = 0x801065e4  XER = 0xa0006d36  DAR = 0xffffffff  DSISR = 0xffffffff
DEC = 0xffffffff  TBU = 0xffffffff  TBL = 0xffffffff  IMMR  = 0xffffffff
R0  = 0x00000000  R1  = 0x80005ea8  R2  = 0xffffffff  R3    = 0x00000000
R4  = 0x8fab0d76  R5  = 0x80657d00  R6  = 0x80570000  R7    = 0x80570000
R8  = 0x00000000  R9  = 0x80570000  R10 = 0x0000954c  R11   = 0x00000000
R12 = 0x00000080  R13 = 0xffffffff  R14 = 0xffffffff  R15   = 0xffffffff
R16 = 0xffffffff  R17 = 0xffffffff  R18 = 0xffffffff  R19   = 0xffffffff
R20 = 0xffffffff  R21 = 0xffffffff  R22 = 0xffffffff  R23   = 0xffffffff
R24 = 0xffffffff  R25 = 0xffffffff  R26 = 0xffffffff  R27   = 0xffffffff
R28 = 0xffffffff  R29 = 0xffffffff  R30 = 0xffffffff  R31   = 0xffffffff
frame—displays an individual stack frame. 
sysret—displays return information from the last booted system image. This information includes 
the reason for terminating the image, a stack dump of up to eight frames, and, if an exception is 
involved, the address where the exception occurred; for example:
rommon 8> sysret
System Return Info:
count: 19,  reason: user break
pc:0x801111b0,  error address: 0x801111b0
Stack Trace:
FP: 0x80005ea8, PC: 0x801111b0
FP: 0x80005eb4, PC: 0x80113694
FP: 0x80005f74, PC: 0x8010eb44
FP: 0x80005f9c, PC: 0x80008118
FP: 0x80005fac, PC: 0x80008064
FP: 0x80005fc4, PC: 0xfff03d70
FP: 0x80005ffc, PC: 0x00000000
FP: 0x00000000, PC: 0x00000000
meminfo—displays size in bytes, starting address, available range of main memory, the starting 
point and size of packet memory, and size of NVRAM; for example:
rommon 9> meminfo
Main memory size: 40 MB.
Available main memory starts at 0x10000, size 40896KB 
						

							  
B-10
Cisco 826, 827, 828, 831, 836, and 837 and Cisco SOHO 76, 77, 78, 91, 96, and 97 Routers Software Configuration Guide
78-14565-03
Appendix B      ROM Monitor
Exiting the ROM Monitor
IO (packet) memory size: 5 percent of main memory.
NVRAM size: 32KB
Exiting the ROM Monitor
You must set the configuration register to a value from 0x2 to 0xF for the router to boot a Cisco IOS 
image from Flash memory upon startup or reloading. 
The following example shows how to reset the configuration register and cause the router to boot a 
Cisco IOS image stored in Flash memory:
rommon 1 > confreg 0x2101
You must reset or power cycle for new config to take effect
rommon 2 >boot
The router will boot the Cisco IOS image in Flash memory. The configuration register will change to 
0x2101 the next time the router is reset or power cycled. 
						

							  
C-1
Cisco 826, 827, 828, 831, 836, and 837 and Cisco SOHO 76, 77, 78, 91, 96, and 97 Routers Software Configuration Guide
78-14565-03
APPENDIXC
Common Port Assignments
Ta b l e C - 1 lists currently assigned Transmission Control Protocol (TCP) port numbers. To the extent 
possible, the User Datagram Protocol (UDP) uses the same numbers.
Table C-1 Currently Assigned TCP and UDP Port Numbers
Port Keyword Description
0–Reserved
1–4–Unassigned
5 RJE Remote job entry
7ECHO Echo
9 DISCARD Discard
11 USERS Active users
13 DAYTIME Daytime
15 NETSTAT Who is up or NETSTAT
17 QUOTE Quote of the day
19 CHARGEN Character generator
20 FTP-DATA File Transfer Protocol (data)
21 FTP File Transfer Protocol
23 TELNET Terminal connection
25 SMTP Simple Mail Transport Protocol
37 TIME Time
39 RLP Resource Location Protocol
42 NAMESERVER Host Name Server
43 NICNAME Who is
49 LOGIN Login Host Protocol 
53 DOMAIN Domain Name Server
67 BOOTPS Bootstrap Protocol Server
68 BOOTPC Bootstrap Protocol Client
69 TFTP Trivial File Transfer Protocol
75–Any private dial-out service 
						

							  
C-2
Cisco 826, 827, 828, 831, 836, and 837 and Cisco SOHO 76, 77, 78, 91, 96, and 97 Routers Software Configuration Guide
78-14565-03
Appendix C      Common Port Assignments
77–Any private RJE service
79 FINGER Finger
95 SUPDUP SUPDUP Protocol
101 HOST NAME NIC host name server
102 ISO-TSAP ISO-Transport Service Access Point
 
(
TSAP)
103 X400 X400
104 X400-SND X400-SND
111 SUNRPC SUN Remote Procedure Call 
113 AUTH Authentication Service
117 UUCP-PATH UNIX-to-UNIX Copy Protocol 
(UUCP) Path Service
119 NNTP Usenet Network News Transfer 
Protocol
123 NTP Network Time Protocol
126 SNMP Simple Network Management 
Protocol
137 NETBIOS-NS NETBIOS name service
138 NETBIOS-DGM NETBIOS datagram service
139 NETBIOS-SSN NETBIOS session service
161 SNMP Simple Network Management 
Protocol
162 SNMP-TRAP Simple Network Management 
Protocol traps
512 rexec UNIX rexec (control)
513 TCP—rlogin
UDP—rwhoTCP—UNIX rlogin
UDP—UNIX broadcast name 
service
514 TCP—rsh
UDP—syslogTCP—UNIX rsh and log
515 Printer UNIX line printer remote spooling
520 RIP Routing Information Protocol 
525 Timed Time server 
Table C-1 Currently Assigned TCP and UDP Port Numbers (continued)
Port Keyword Description 
						

							  
IN-1
Cisco 826, 827, 828, 831, 836, and 837 and Cisco SOHO 76, 77, 78, 91, 96, and 97 Routers Software Configuration Guide
78-14565-03
INDEX
Symbols
-? commandB-3
? commandA-4, B-3
A
AAL1-7
AAL3/41-7
AAL51-7
AAL5MUXPPP encapsulation configuration example3-8
AAL5SNAP encapsulation configuration example3-7, 
3-10
abbreviating commandsA-6
access lists1-13, 3-23 to 3-24
ACK bits1-13
addressing, configuring3-15 to 3-22
Address Resolution Protocol
See ARP
ADSL
benefits of
2-3, 2-5
network connections with2-3, 2-5
ordering2-6, 3-2
overview1-3
Alcatel 1000 bridge, replacing2-6 to 2-8
ARP1-3
Asymmetric Digital Line Subscriber Line
See ADSL
ATM
configuring the ATM interface
2-10
errors, displaying5-8
events, displaying5-9
interface
configuration scenario
2-14
configuring3-7
network example2-15 to 2-16
overview1-7
packets, displaying5-10
PVC encapsulation types1-7
queues1-12
troubleshooting commands5-5 to 5-11
ATM adaptation layer
See AAL
ATM interface
See ATM
audience, user
xi
authentication protocols
See PPP authentication protocols
B
bB-3
basic telephone service
See POTS dial peer
b flash command
B-3
boot commandsB-3
bootstrap program
See ROM monitor
bridge, replacing
2-6 to 2-8
bridging
configuration example
3-10
configuring3-9 to 3-11
broadcast intervals, RIP1-4 
						

							  
Index
IN-2
Cisco 826, 827, 828, 831, 836, and 837 and Cisco SOHO 76, 77, 78, 91, 96, and 97 Routers Software Configuration Guide
78-14565-03
C
call1-11
call leg, defining a1-11
CAR1-12
caution, describedxii
CBWFQ1-12
CD-ROM, documentationxiv
Central RADIUS Server, configuring2-43
CHAP1-5, 1-6
Cisco 831 router VPN connections2-3
Cisco documentationxiv
Cisco IOS
queues
1-13
class-based weighted fair queuing
See CBWFQ
command(s)
copy running-config startup-config
A-7
debug atm errors5-8
debug atm events5-9
debug atm packet5-10 to 5-11
destination-pattern1-11
flowcontrolA-2
ip precedence3-25, 3-33
ip rsvp bandwidth3-33
ip rtp reserve3-32
num-exp3-50
permit1-13
port1-11
req-qos3-34
session target1-11
show atm interface5-7
show dialplan number3-51
show num-exp3-50
vbr-nrt3-7
vbr-rt3-7
command conventionsxiii
command-line access to router, configuring3-9
command modesA-2 to A-4
commands
-?
B-3
?B-3
abbreviatingA-6
ATM troubleshooting5-5 to 5-11
b flashB-3
bootB-3
completingA-4
confregB-6
contextB-9
copy tftp flashB-3
debug ATM5-11
debug atm5-8
devB-3
dir deviceB-3
finding availableA-4
frameB-9
helpB-3
help withA-4
iB-3
kB-9
meminfoB-9
privileged EXEC, accessingA-5
redisplayingA-5
resetB-3
ROM monitorB-2 to B-3
ROM monitor debuggingB-9
stackB-9
sysretB-9
tftpdnldB-4
undoingA-6
xmodemB-8
command variables
listing
A-5
TFTP downloadB-4
committed access rate
See CAR
configuration, feature by feature
3-1, 4-1