Originally posted at http://www.nthelp.com/handy_cisco.htm, but that site no longer exists.

to add a route:
config t
ip route ipaddress subnetmask destination

to remove a route:
config t
no ip route ipaddress subnetmask destination

to null route an IP address:
config t
ip route ipaddress subnetmask null0

to find a dsl login:
sh user | include xxxxx
where xxxxx = either the login name or IP address

to show interfaces of a certain type quickly:
sh ip int brief | include ATM
where ATM can be whatever text identifies the interfaces

to show how much is blocked by access lists:
sh access-lists

to find a DSL user on a specific IP:
sh caller ip | include ipaddress

to reset a DSL user:
clear int vi4.28

to reinit a DSL user:
config t
int atm5/ima2.100 POI (or whatever their interface number is)
shut
no shut
exit

to track down non-existant dsl user:
config t
logging 216.144.x.x (ip of syslog host)
debug pppoe or pppatm or whatever events you need.
debug ppp authentication
debug vpdn pppoe-events (att or sbc)
no debug all (to turn it off)

cle router
term mon
debug ppp auth
debug pppoe event (watch for login and write it down with vpi/vci)
no debug all
term no mon

ATM pinging from a cisco:
ping ATM INT a5/ima1.100 vpi vci e
Example: ping atm int a5/ima1.100 1 83 e
the e means ping endpoint.

Explains how to use a cisco router to track a flood

columbus- build a dlci based dsl interface
config t
int s2/1.136 poi
frame-relay interface-dlci 136 IETF
exit (once)
bridge-group 1

columbus find user
r-col1#sh arp | include 216.144.63.24
Internet 216.144.63.24 18 0010.dcf8.1dd1 ARPA BVI1

r-col1#sh bridge 1 | include 0010.dcf8.1dd1
0010.dcf8.1dd1 forward Serial6/0.131 0 627740 172240

lookup dlci 131 in chart

Access Lists (hssi1/0.500 and hssi2/0)
clear ip access-lists counters
sh ip access-lists 152
no ip access-group 152 out

Hung VPDN tunnels
sh vpdn tunnel sum
look for wt-ctl
sh config and look for atm5/ima1.something
config t to shut no shut