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

- When a secure port is in the error-disabled (shutdown) state caused by a security violation, it can
be re-enabled with the series of shutdown and no shutdown interface subcommands.
- The switchport port-security mac-address sticky interface subcommand enables sticky
learning – dynamically learn the MAC address from the first frame sent into a secure port, and
add the MAC address as a secure MAC address to the running configuration.
- The switchport port-security violation {protect | restrict | shutdown} interface
subcommand configures the violation mode for a secure port. The default action is shutdown.
In restrict and protect modes, frames with unauthorized MAC addresses are discarded instead of
shutting down the secure port, and a log entry will (restrict) or will not (protect) be made.
- The switchport port-security maximum [num] interface subcommand changes the
maximum secure MAC addresses that will be allowed for a secure port. The default value is 1.
Spanning Tree Protocol Configuration
- STP is enabled by default in Catalyst switches, and hence no configuration is needed when
connecting new switches that are out of the boxes, as STP will ensure that no loop can exist.
- In the following example, SW1 and SW2 were connected together at Fa0/1 and Fa0/2, and SW1
as the initial root bridge. Let’s begin by listing the spanning tree information, followed by
configuring SW2’s Fa0/2 as the root port by changing the STP port cost. Finally, SW2 has been
configured as the root bridge by changing the bridge priority with the spanning-tree vlan
{vlan-id} root primary global configuration command.
SW2#sh spanning-tree
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address aaaa.aaaa.aaaa
Cost 19
Port 1 (FastEthernet0/1)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address bbbb.bbbb.bbbb
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- -------------------------------
Fa0/1 Root FWD 19 128.1 P2p
Fa0/2 Altn BLK 19 128.2 P2p
SW2#debug spanning-tree events
Spanning Tree event debugging is on
SW2#
SW2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
SW2(config)#int fa0/2
SW2(config-if)#spanning-tree cost 10
SW2(config-if)#^Z
SW2#
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