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From: Question 1
Subject: What does ``cisco'' stand for?
cisco folklore time:
At one point in time, the first letter in cisco Systems was a lowercase ``c''. At present, various factions within the company have adopted a capital ``C'', while fierce traditionalists (as well as some others) continue to use the lowercase variant, as does the cisco Systems logo. This FAQ has chosen to use the lowercase variant throughout.
cisco is not C.I.S.C.O. but is short for San Francisco, so the story goes. Back in the early days when the founders Len Bosack and Sandy Lerner and appropriate legal entities were trying to come up with a name they did many searches for non similar names, and always came up
with a name which was denied. Eventually someone suggested ``cisco'' and the name wasn't taken (although SYSCO may be confusingly similar sounding). There was an East Coast company which later was using the ``CISCO'' name (I think they sold in the IBM marketplace) they ended up having to not use the CISCO abberviation. Today many people spell cisco with a capital ``C'', citing problems in getting the lowercase ``c'' right in publications, etc. This lead to at least one amusing article headlined ``Cisco grows up''. This winter we will celebrate our 10th year.
[This text was written in July of 1994 -jhawk]
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From: Question 2
Subject: How do I save the configuration of a cisco?
If you have a tftp server available, you can create a file on the server for your router to write to, and then use the write network command. From a typical unix system:
mytftpserver$ touch /var/spool/tftpboot/myconfig
mytftpserver$ chmod a+w /var/spool/tftpboot/myconfig
myrouter#copy running-config tftp
Remote host [10.7.0.63]? 10.7.0.2
Name of configuration file to write [myrouter-confg]? myconfig
Write file foobar on host 10.7.0.2? [confirm] y
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From: Question 3
Subject: How can I get my cisco to talk to a third party router over a serial link?
You need to tell your cisco to use the same link-level protocol as the other router; by default, ciscos use a rather bare variant of HDLC (High-level Data Link Control) all link-level protocols use at some level/layer or another. To make your cisco operate with most other routers, you need to change the encapsulation from HDLC to PPP on the
relevant interfaces. For instance:
sewer-cgs#conf t
Enter configuration commands, one per line.
Edit with DELETE, CTRL/W, and CTRL/U; end with CTRL/Z
interface serial 1
encapsulation ppp
^Z
sewer-cgs#sh int s 1
Serial 1 is administratively down, line protocol is down
Hardware is MCI Serial
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation PPP, loopback not set, keepalive set (10 sec)
^^^^^^^^^^^^^^^^^^^^^^^^^^
[...]
If you're still having trouble, you might wish to turn on serial interface debugging:
sewer-cgs#ter mon
sewer-cgs#debug serial-interface
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From: Question 4
Subject: How can I get my cisco to talk to a 3rd-party router over Frame Relay?
You should tell your cisco to use ``encapsulation frame-relay ietf'' (instead of ``encapsulation frame-relay'') on your serial interface that's running frame relay if your frame relay network contains a diverse set of manufacturers' routers. The keyword ``ietf'' specifies that your cisco will use
RFC1294-compliant encapsulation, rather than the default,
RFC1490-compliant encapsulation (other products, notably Novell MPR 2.11, use a practice sanctioned by 1294 but deemed verbotten by 1490, namely padding of the nlpid). If only a few routers in your frame relay cloud require this, then you can use the default encapsulation on everything and specify the exceptions with the frame-relay map command:
frame-relay map ip 10.1.2.3 56 broadcast ietf
^^^^
(ietf stands for Internet Engineering Task Force, the body which evaluates Standards-track RFCs; this keyword is a misnomer as both
RFC1294 and
RFC1490 are ietf-approved, however 1490 is most recent and is a Draft Standard (DS), whereas 1294 is a Proposed Standard (one step beneath a DS), and is effectively obsolete).
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From: Question 5
Subject: How can I use debugging?
The ``terminal monitor'' command directs your cisco to send debugging output to the current session. It's necessary to turn this on each time you telnet to your router to view debugging information. After that, you must specify the specific types of debugging you wish to turn on; please note that these stay on or off until changed, or until the router reboots, so remember to turn them off when you're done.
Debugging messages are also logged to a host if you have trap logging enabled on your cisco. You can check this like so:
sl-panix-1>sh logging
Syslog logging: enabled (0 messages dropped, 0 flushes, 0 overruns)
Console logging: level debugging, 66 messages logged
Monitor logging: level debugging, 0 messages logged
Trap logging: level debugging, 69 message lines logged
Logging to 198.7.0.2, 69 message lines logged
sl-panix-1>
If you have syslog going to a host somewhere and you then set about a nice long debug session from a term your box is doing double work and sending every debug message to your syslog server. Additionally, if you turn on something that provides copious debugging output, be careful that you don't overflow your disk (``debug ip-rip'' is notorious for this).
One solution to this is to only log severity ``info'' and higher:
sl-panix-1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
logging trap info
The other solution is to just be careful and remember to turn off debugging. This is easy enough with:
sl-panix-1#undebug all
If you have a heavily loaded box, you should be aware that debugging can load your router. The console has a higher priority than a vty so don't debug from the console; instead, disable console logging:
cix-west.cix.net#conf t
Enter configuration commands, one per line. End with CNTL/Z.
no logging console
Then always debug from a vty. If the box is busy and you are a little too vigorous with debugging and the box is starting to sink, quickly run, don't walk to your console and kill the session on the vty. If you are on the console your debugging has top prioority and then the only way out is the power switch. This of course makes remote debugging a real sweaty palms adventure especially on a crowded box.
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From: Question 6
Subject: How do I avoid the annoying DNS lookup if I have misspelled a command?
Use the command
No ip domain-lookup