CCNA Complete Guide 2nd Edition.pdf - Cisco Learning Home

- Tips: The show controllers {intf-type intf-num} EXEC command can be used to find out
which end (DTE or DCE) is plugged into a serial interface:
Router#show controllers serial 0/0
HD unit 0, idb = 0xC2518, driver structure at 0xC79B0
buffer size 1524 HD unit 0, V.35 DCE cable
cpb = 0xE1, eda = 0x4940, cda = 0x4800
RX ring with 16 entries at 0xE14800
- The terminal ip netmask-format {bit-count | decimal} EXEC command can be used to
change the network mask format (prefix notation – /xx or dotted decimal – x.x.x.x) in the
output of the series of show command, eg: show ip route.
- Troubleshooting network problems with ping:
Error Message Possible Cause
Destination host unreachable Packet dropped on the way to the destination. Normally
returned by an intermediate router when it is not able to find a
route to the destination network.
Request timed out Packet dropped on the way to the destination. Another
possible cause is an intermediate router does not have a route to
the network of the source host when the packet is on the way
back from the destination network.
Static Routing Configuration
- Currently, a Request timed out error message would be received when trying to ping
192.168.2.2 from PC1. This is due to RT2 does not have a route to 192.168.1.0/24 network!
This section shows the static routing configuration on all routers for them to reach all networks.
- The ip route {destination-network} {subnet-mask} {next-hop-addr | outgoing-intf}
[administrative-distance] [permanent] global configuration command defines static routes.
Note: Static routes that use the outgoing interface option instead of the next-hop address option
are considered as directly connected static routes.
Note: Only configure static routes pointing to an outgoing interface on point-to-point links, as
the router won’t be able to resolve a next-hop address in point-to-multipoint topologies.
- Static Routing configuration on RT1:
RT1(config)#ip route 192.168.3.0 255.255.255.0 192.168.2.2
RT1(config)#ip route 192.168.4.0 255.255.255.0 192.168.2.2
RT1(config)#ip route 192.168.5.0 255.255.255.0 192.168.2.2
RT1(config)#^Z
RT1#
RT1#sh ip route
Gateway of last resort is not set
C 192.168.1.0/24 is directly connected, FastEthernet1/0
C 192.168.2.0/24 is directly connected, Serial0/0
S 192.168.3.0/24 [1/0] via 192.168.2.2
S 192.168.4.0/24 [1/0] via 192.168.2.2
S 192.168.5.0/24 [1/0] via 192.168.2.2
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