© 2004 Cisco Systems, Inc. All rights reserved. Printed in USA.
Presentation_ID.scr
474747
© 2004 Cisco Systems, Inc. All rights reserved.
RST-3508
9805_05_2004_c2
L2 Forwarding Tables to Verify
Reachability
cat4500#show mac-address-table count
MAC Entries for all vlans:
Dynamic Unicast Address Count: 6
Static Unicast Address (User-defined) Count: 0
Static Unicast Address (System-defined) Count: 1
Total Unicast MAC Addresses In Use: 7
Total Unicast MAC Addresses Available: 32768
Multicast MAC Address Count: 11
Total Multicast MAC Addresses Available: 16384
cat4500#show mac-address-table dynamic
Unicast Entries
vlan mac address type protocols port
-------+---------------+--------+---------------------+--------------------
1 0000.0c07.ac01 dynamic ip FastEthernet3/37
1 0009.e845.64bf dynamic ip FastEthernet3/37
1 0030.7b4e.340a dynamic ip,assigned FastEthernet3/37
41 0000.0c07.ac29 dynamic ip FastEthernet3/19
50 0000.0c07.ac32 dynamic ip FastEthernet3/19
50 000a.4172.df7f dynamic ip FastEthernet3/19
cat4500#show mac-address-table address 0000.0c07.ac29
Unicast Entries
vlan mac address type protocols port
-------+---------------+--------+---------------------+--------------------
41 0000.0c07.ac29 dynamic ip FastEthernet3/19
484848
© 2004 Cisco Systems, Inc. All rights reserved.
RST-3508
9805_05_2004_c2
Show Interface Error Counters
• FCS-err is the number of valid size frames with FCS (frame check sequence) errors but no
framing errors; this is typically a physical issue (cabling, bad port, NIC card,…) but can also
indicate a duplex mismatch
• Align-err is the number of frames with alignment errors (frames that do not end with an even
number of octets and have a bad CRC) received on the port; these usually indicate a physical
problem (cabling, bad port, NIC card,…) but can also indicate a duplex mismatch; when the
cable is first connected to the port, some of these errors may occur; also, if there is a hub
connected to the port then collisions between other devices on the hub may cause these errors
• Late-coll (late collisions) is the number of times that a collision is detected on a particular port
late in the transmission process; for a 10Mbit/s port this is later than 512 bit-times into the
transmission of a packet; five hundred and twelve bit-times corresponds to 51.2 microseconds
on a 10 Mbit/s system; this error can indicate a duplex mismatch among other things; for the
duplex mismatch scenario the late collision would be seen on the half duplex side; as the half
duplex side is transmitting, the full duplex side does not wait its turn and transmits
simultaneously causing a late collision; late collisions can also indicate an Ethernet
cable/segment that is too long; collisions should not be seen on ports configured as full duplex
• Single-coll (single collision) is the number of times one collision occurred before the port
transmitted a frame to the media successfully; collisions are normal for port configured as half
duplex but should not be seen on full duplex ports; if collisions are increasing dramatically this
points to a highly utilized link or possibly a duplex mismatch with the attached device
• Multi-coll (multiple collision) is the number of times multiple collisions occurred before the port
transmitted a frame to the media successfully; collisions are normal for port configured as half
duplex but should not be seen on full duplex ports; if collisions are increasing dramatically this
points to a highly utilized link or possibly a duplex mismatch with the attached device
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