Layer 3
When troubleshooting Layer 3 issues, verify:
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The IP address assigned to each VLAN (Virtual LAN) router interface.
-
To display summary information for all of the VLANs
configured on the device, use the show vlan
command.
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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
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
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
OSPF is applicable only in IPv4
environments.
-
To display OSPF information, use the following
commands:
-
Your OSPFv3 (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
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
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 Generation) configuration,
including RIPng poison reverse, split horizon, triggered updates, transmit version, and
receive version.
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
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.
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The routed path between the switch and a destination
end station.
-
To verify and trace the routed path, use the traceroute command.