A router can be limited by its available memory. To show the used and available memory,
Router#show proc mem At the beginning of the output, look for a line like this:
Total: 200234528, Used: 70508188, Free: 129726340
Show proccessor load of your router or switch,which can be limited by its processing power. To show the processor utilization,
Router#show proc cpu
At the beginning of the output, look for a line like this:
CPU utilization for five seconds: 37%/30%; one minute: 39%; five minutes: 40%
Learn the command-line editing keys.
Control A Goes to the beginning of the line
Control E Goes to the end of the line
Control K Deletes everything to the right of the cursor
Control P Recalls the previous command in the history buffer
Control N Recalls the next command in the history buffer
No browsing.... A common access-list pitfall is when people forget to allow DNS (Domain Name Servers) from their internal network to the provider's DNS servers. Mainly this is a problem on home or small office routers where you might not have an internal DNS server running. The following command allows DNS access from your hosts to the outside DNS server. In this example, our outside DNS servers are 192.168.30.11 and 192.168.30.12
access-list 110 permit udp host 192.168.30.11 eq domain any gt 1023
access-list 110 permit udp host 192.168.30.12 eq domain any gt 1023
Some are having some problems on the ICMP access-list. Try this oneallow pings into the network
access-list 110 permit icmp any any echo
! allow ping responses
access-list 110 permit icmp any any echo-reply
! allow ICMP source-quench
access-list 110 permit icmp any any source-quench
! allow path MTU discovery
access-list 110 permit icmp any any packet-too-big
! allow time-exceeded, which is useful for traceroute
access-list 110 permit icmp any any time-exceeded
! deny all other ICMP packets
access-list 110 deny icmp any any
Stopping the router from crazy output... An annoying problem output everytime you mistype a command and the router thinks you just typed a hostname. For example: The way to handle this is to change the preferred transport method: The output shows the lack of a failed connection based on our mistyped keyword:
Router#shwo
Translating "shwo"...domain server (10.1.1.1)
% Unknown command or computer name, or unable to find computer address
Router#
! Console port
line con 0
transport preferred none
! VTY Ports
line vty 0 5
transport preferred none
Router#shwo
^
% Invalid input detected at '^' marker.
When everything fails.... hehe
Router#reload in 3
Reload scheduled in 3 minutes
Proceed with reload? [confirm]y
| Router#debug ip igrp events | Shows all IGRP events in real time |
| Router#debug ip igrp transactions | Shows IGRP updates between routers |
| Router(config)#router igrp as-number | Enables IGRP routing process. The autonomous system number (AS-number) used in the IGRP routing process must match all other routers that are going to share routing updates in order for communication to take place |
| Router(config-router)#network w.x.y.z | w.x.y.z is the network number of the directly connected network you want to advertise |
Note:
You need to advertise only the classful network number, not a subnet:
Router(config-router)#network 172.17.0.0 not
Router(config-router)#network 172.17.10.0 If you advertise a subnet, you will not receive an error message, because the router will automatically convert the subnet to the classful network address.
RIP Version 2: Optional Commands
|
| Router(config)#router rip | Turns on the RIP routing process; the same command as used for RIP Version 1 (RIP-1) |
| Router(config-router)#version 2 | Turns on Version 2 of the routing process. Version 1 is default |
| Router(config-router)#network w.x.y.z | w.x.y.z is the network number of the directly connected classful network you want to advertise |
RIP Version 2
| Router(config-router)#version 2 | RIP will now send and receive RIP-2 packets globally |
| Router(config-if)#ip rip send version 1 | Interface will send only RIP-1 packets |
| Router(config-if)#ip rip send version 2 | Interface will send only RIP-2 packets |
| Router(config-if)#ip rip send version 1 2 | Interface will send both RIP-1 and RIP-2 packets |
| Router(config-if)#ip rip receive version 1 | Interface will receive only RIP-1 packets |
| Router(config-if)#ip rip receive version 2 | Interface will receive only RIP-2 packets |
| Router(config-if)#ip rip receive version 1 2 | Interface will receive both RIP-1 and RIP-2 packets |
| Router(config)#no router rip | Turns off the RIP routing process |
| Router(config-router)#no network w.x.y.z | Removes network w.x.y.z from the RIP routing process |
| Router(config-router)#passive-interface s0/0 | RIP updates will not be sent out this interface |
| Router(config-router)#neighbor a.b.c.d | Defines a specific neighbor with which to exchange information |
| Router(config-router)#no ip split-horizon | Turns off split horizon (on by default) |
| Router(config-router)#ip split-horizon | Re-enables split horizon |
| Router(config-router#timers basic 30 90 180 270 360 | Changes timers in RIP: |
| 30 = Update timer (in seconds) | |
| 90 = Invalid timer (in seconds) | |
| 180 = Hold-down timer (in seconds) | |
| 270 = Flush timer (in seconds) | |
| 360 = Sleep time (in milliseconds) | |
| Router(config-router)#maximum-paths x | Limits the number of paths for load balancing to x (4 = default, 6 = maximum) |
| Router(config-router)#default-information originate | Generates a default route into RIP |
| Router(config)#router rip | Enables RIP as a routing protocol |
| Router(config-router)#network 192.168.10.0 | 192.168.10.0 is the network number of the directly connected network you want to advertise |
Note:
You need to advertise only the classful network number, not a subnet:
Router(config-router)#network 172.17.0.0 not
Router(config-router)#network 172.17.10.0 If you advertise a subnet, you will not receive an error message, because the router will automatically convert the subnet to the classful network address.
| Router(config)#ip classless | Instructs IOS to forward packets destined for an unknown subnet to the best supernet route |
| Router(config)#no ip classless | Turns off the ip classless command |
| Router(config)#ip route 172.16.20.0 255.255.255.0 172.16.10.2 permanent | Specifies that the route will not be removed, even if the interface shuts down |
| Router(config)#ip route 172.16.20.0 255.255.255.0 172.16.10.2 | 172.16.20.0 = destination network |
| 255.255.255.0 = subnet mask | |
| 172.16.10.2 = next-hop address | |
| Read this to say: To get to the destination network of 172.16.20.0, with a subnet mask of 255.255.255.0, send all packets to 172.16.10.2 |
| Router(config)#ip route 172.16.20.0 255.255.255.0 s0/0 | 172.16.20.0 = destination network |
| 255.255.255.0 = subnet mask | |
| s0/0 = exit interface | |
| Read this to say: To get to the destination network of 172.16.20.0, with a subnet mask of 255.255.255.0, send all packets out interface Serial 0/0 |
