330
If ping from the switch to directly connected network devices fails, the following can be
used to check the possible cause and create a solution.
z
Check whether the corresponding ARP has been learned by the switch.
z
If ARP has not learned, then enabled ARP debugging information and view
sending/receiving condition of ARP packets.
Defective cable is a common cause of ARP problems and may disable ARP learning.
Command
10.5.3.5 Monitor And Debug Command
10.5.3.5.1 debug arp
Command:debug arp
no debug arp
Function:
Enables the ARP debugging function; the “
no debug arp
”
command disables
this debugging function.
Default:
ARP debug is disabled by default.
Command mode:
Admin Mode
Usage Guide:
Display contents for ARP packets received/sent, including type, source
and destination address, etc.
Example:
Enable ARP debugging
Switch#debug arp
ip arp debug is on
Switch#Apr 19 15:59:42 2005 IP ARP: rcvd, type 1, src 192.168.2.100, 000A.EB5B.
780C, dst 192.168.2.1, 0000.0000.0000 flag 0x0.
Apr 19 15:59:42 2005 IP ARP: sent, type 2, src 192.168.2.1, 0003.0F02.310A, dst
192.168.2.100, 000A.EB5B.780C.
10.5.3.5.2 show arp
Command: show arp [<ip-addr>][<vlan-id>][<hw-addr>][type
{static|dynamic}][count] }
Function:
Displays the ARP table.
Parameters:
<ip-addr>
is a specified IP address;
<vlan-id>
stands for the entry for the
identifier of specified VLAN;
<hw-addr>
for entry of specified MAC address; “static” for
static ARP entry; “dynamic” for dynamic ARP entry; “count” displays number of ARP
entries.
Command mode:
Admin Mode
Usage Guide:
Displays the content of current ARP table such as IP address, MAC
address, hardware type, interface name, etc.
Example:
Switch#sh arp
Total arp items: 3, matched: 3, Incomplete: 0
