Layer 3
When troubleshooting Layer 3 issues, verify:
-
The IP address assigned to each VLAN router
interface.
-
To display summary information for all of the VLANs
configured on the device, use the show vlan command.
-
That IP forwarding is enabled, the routing protocol is
globally enabled, and the routing protocol is enabled for a VLAN.
-
To display the configuration information
for a specific VLAN, use one of the following commands:
-
Which destination networks are in the routing table and
the source of the routing entry.
-
To display the contents of the routing table
or the route origin priority, use one of the following commands:
-
To display the contents of the routing table only
for routes of a specified origin, use one of the following commands:
-
That the IP Address Resolution Protocol (ARP) table has
the correct entries.
![Note](./images/Note_Note.png)
Note
The ARP table is applicable only in IPv4
environments.
-
To display the contents of the IP ARP table, use the
show
iparp command.
-
That the Neighbor Discovery (ND) cache has the correct
entries.
![Note](./images/Note_Note.png)
Note
The ND cache is applicable only in IPv6
environments.
-
To display the contents of the ND cache, use the show
neighbor-discovery cache ipv6 command.
-
IP routing protocol statistics for the CPU of the switch.
-
Only statistics of the packets handled by
the CPU are displayed. To display IP statistics for the CPU of the
switch, use one of the following commands:
-
Your OSPF (Open Shortest Path First) configuration,
including the OSPF area ID, router state, link cost, OSPF timers, interface IP address,
and neighbor list.
![Note](./images/Note_Note.png)
Note
OSPF is applicable only in IPv4
environments.
-
To display OSPF information, use the following
commands:
-
Your Open Shortest Path First version 3 configuration,
including the OSPFv3 area ID, router state, link cost, OSPFv3 timers, interface IP
address, and neighbor list.
OSPFv3 is applicable only in IPv6 environments.
-
To display OSPFv3 information, use the following
commands:
-
Your RIP (Routing Information Protocol) configuration,
including RIP poison reverse, split horizon, triggered updates, transmit version, and
receive version.
![Note](./images/Note_Note.png)
Note
RIP is applicable only in IPv4
environments.
-
To display detailed information about how you have RIP
configured on the switch, use the show rip
command.
-
RIP activity and statistics for all VLANs on the switch.
![Note](./images/Note_Note.png)
Note
RIP is applicable only in IPv4
environments.
-
To display RIP-specific statistics for all VLANs, use
the show
rip interface detail command.
-
Your RIPng (Routing Information Protocol Next Genreation) configuration,
including RIPng poison reverse, split horizon, triggered updates, transmit version, and
receive version.
![Note](./images/Note_Note.png)
Note
RIPng is applicable only in IPv6
environments.
-
To display detailed information about how you have
RIPng configured on the switch, use the show ripng command.
-
RIPng activity and statistics for all VLANs on the switch.
![Note](./images/Note_Note.png)
Note
RIPng is applicable only in IPv6
environments.
-
To display RIPng-specific statistics for all VLANs,
use the show ripng interface command.
-
End-to-end connectivity.
-
To test for connectivity to a specific host, use the
ping command.
-
The routed path between the switch and a destination
end station.
-
To verify and trace the routed path, use the traceroute command.