Consolidated Platform Configuration Guide, Cisco IOS XE 3.7E and Later (Catalyst 3650 Switches)
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feature is supported, see the feature information table at the end of this
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Information About Administering the Switch
System Time and Date Management
You can manage the system time and date on your
switch
using automatic configuration methods
(RTC and NTP), or manual
configuration methods.
Note
For complete syntax
and usage information for the commands used in this section, see the
Cisco IOS
Configuration Fundamentals Command Referenceon
Cisco.com.
System Clock
The basis of the time service
is the system clock. This clock runs from the moment the system starts up and
keeps track of the date and time.
The system clock can then be
set from these sources:
NTP
Manual configuration
The system clock can provide
time to these services:
User
show commands
Logging and debugging
messages
The system clock keeps track
of time internally based on Coordinated Universal Time (UTC), also known as
Greenwich Mean Time (GMT). You can configure information about the local time
zone and summer time (daylight saving time) so that the time appears correctly
for the local time zone.
The system clock keeps
track of whether the time is
authoritative or
not (that is, whether it has been set by a time source considered to be
authoritative). If it is not authoritative, the time is available only for
display purposes and is not redistributed.
Network Time Protocol
The NTP is designed to time-synchronize a network of
devices. NTP runs over User Datagram Protocol (UDP), which runs over IP. NTP is
documented in RFC 1305.
An NTP network usually gets its time from an authoritative
time source, such as a radio clock or an atomic clock attached to a time
server. NTP then distributes this time across the network. NTP is extremely
efficient; no more than one packet per minute is necessary to synchronize two
devices to within a millisecond of one another.
NTP uses the concept
of a
stratum to
describe how many NTP hops away a device is from an authoritative time source.
A stratum 1 time server has a radio or atomic clock directly attached, a
stratum 2 time server receives its time through NTP from a stratum 1 time
server, and so on. A device running NTP automatically chooses as its time
source the device with the lowest stratum number with which it communicates
through NTP. This strategy effectively builds a self-organizing tree of NTP
speakers.
NTP avoids
synchronizing to a device whose time might not be accurate by never
synchronizing to a device that is not synchronized. NTP also compares the time
reported by several devices and does not synchronize to a device whose time is
significantly different than the others, even if its stratum is lower.
The communications
between devices running NTP (known as associations) are usually statically
configured; each device is given the IP address of all devices with which it
should form associations. Accurate timekeeping is possible by exchanging NTP
messages between each pair of devices with an association. However, in a LAN
environment, NTP can be configured to use IP broadcast messages instead. This
alternative reduces configuration complexity because each device can simply be
configured to send or receive broadcast messages. However, in that case,
information flow is one-way only.
The time kept on a
device is a critical resource; you should use the security features of NTP to
avoid the accidental or malicious setting of an incorrect time. Two mechanisms
are available: an access list-based restriction scheme and an encrypted
authentication mechanism.
Cisco’s implementation
of NTP does not support stratum 1 service; it is not possible to connect to a
radio or atomic clock. We recommend that the time service for your network be
derived from the public NTP servers available on the IP Internet.
The Figure shows a
typical network example using NTP.
Switch
A is the NTP master, with the
Switch
B, C, and D configured in NTP server mode, in server association with
Switch
A.
Switch
E is configured as an NTP peer to the upstream and downstream
Switch,
Switch
B and
Switch
F, respectively.
Figure 1. Typical NTP
Network Configuration
If the network is
isolated from the Internet, Cisco’s implementation of NTP allows a device to
act as if it is synchronized through NTP, when in fact it has learned the time
by using other means. Other devices then synchronize to that device through
NTP.
When multiple sources
of time are available, NTP is always considered to be more authoritative. NTP
time overrides the time set by any other method.
Several manufacturers
include NTP software for their host systems, and a publicly available version
for systems running UNIX and its various derivatives is also available. This
software allows host systems to be time-synchronized as well.
NTP Stratum
NTP uses the concept of a stratum to describe how many NTP hops away a device is from an authoritative time source. A stratum 1 time server has a radio or
atomic clock directly attached, a stratum 2 time server receives its time through NTP from a stratum 1 time server, and so
on. A device running NTP automatically chooses as its time source the device with the lowest stratum number with which it
communicates through NTP. This strategy effectively builds a self-organizing tree of NTP speakers.
NTP avoids synchronizing to a device whose time might not be accurate by never synchronizing to a device that is not synchronized.
NTP also compares the time reported by several devices and does not synchronize to a device whose time is significantly different
than the others, even if its stratum is lower.
NTP Associations
The communications between devices running NTP (known as associations) are usually statically configured; each device is given the IP address of all devices with which it should form associations.
Accurate timekeeping is possible by exchanging NTP messages between each pair of devices with an association. However, in
a LAN environment, NTP can be configured to use IP broadcast messages instead. This alternative reduces configuration complexity
because each device can simply be configured to send or receive broadcast messages. However, in that case, information flow
is one-way only.
NTP Security
The time kept on a device is a critical resource; you should use the security features of NTP to avoid the accidental or malicious
setting of an incorrect time. Two mechanisms are available: an access list-based restriction scheme and an encrypted authentication
mechanism.
NTP Implementation
Implementation of NTP does not support stratum 1 service; it is not possible to connect to a radio or atomic clock. We recommend
that the time service for your network be derived from the public NTP servers available on the IP Internet.
Figure 2. Typical NTP Network Configuration. The following figure shows a typical network example using NTP. Switch A is the NTP master, with the Switch B, C, and
D configured in NTP server mode, in server association with Switch A. Switch E is configured as an NTP peer to the upstream
and downstream switches, Switch B and Switch F, respectively.
If the network is isolated from the Internet, NTP allows a device to act as if it is synchronized through NTP, when in fact
it has learned the time by using other means. Other devices then synchronize to that device through NTP.
When multiple sources of time are available, NTP is always considered to be more authoritative. NTP time overrides the time
set by any other method.
Several manufacturers include NTP software for their host systems, and a publicly available version for systems running UNIX
and its various derivatives is also available. This software allows host systems to be time-synchronized as well.
NTP Version 4
NTP version 4 is implemented
on the
switch. NTPv4 is an extension of NTP version
3. NTPv4 supports both IPv4 and IPv6 and is backward-compatible with NTPv3.
NTPv4 provides these
capabilities:
Support for IPv6.
Improved security compared to
NTPv3. The NTPv4 protocol provides a security framework based on public key
cryptography and standard X509 certificates.
Automatic calculation of the
time-distribution hierarchy for a network. Using specific multicast groups,
NTPv4 automatically configures the hierarchy of the servers to achieve the best
time accuracy for the lowest bandwidth cost. This feature leverages site-local
IPv6 multicast addresses.
For details about configuring NTPv4, see the
Implementing NTPv4 in IPv6 chapter of the
Cisco IOS IPv6 Configuration Guide, Release 12.4T.
System Name and
Prompt
You configure the system name
on the
Switch
to identify it. By default, the system name and prompt are
Switch.
If you have not configured a system prompt, the first 20
characters of the system name are used as the system prompt. A greater-than
symbol [>] is appended. The prompt is updated whenever the system name
changes.
For complete syntax
and usage information for the commands used in this section, see the
Cisco IOS
Configuration Fundamentals Command Reference,
Release
12.4 and the
Cisco IOS IP
Command Reference,
Volume 2 of 3:
Routing Protocols,
Release
12.4.
Stack System Name
and Prompt
If you are accessing a stack
member through the
active switch, you must use the
sessionstack-member-number privileged EXEC command. The
stack member number range is
. When you use this command, the stack
member number is appended to the system prompt. For example, Switch-2# is the
prompt in privileged EXEC mode for stack member 2, and the system prompt for
the switch stack is Switch.
Default System Name and Prompt Configuration
The default switch system name and prompt is Switch.
DNS
The DNS protocol controls the Domain Name System (DNS), a distributed database with which you can map hostnames to IP addresses.
When you configure DNS on your switch, you can substitute the hostname for the IP address with all IP commands, such as ping, telnet, connect, and related Telnet support operations.
IP defines a hierarchical naming scheme that allows a device to be identified by its location or domain. Domain names are
pieced together with periods (.) as the delimiting characters. For example, Cisco Systems is a commercial organization that
IP identifies by a com domain name, so its domain name is cisco.com. A specific device in this domain, for example, the File Transfer Protocol (FTP) system is identified as ftp.cisco.com.
To keep track of domain names, IP has defined the concept of a domain name server, which holds a cache (or database) of names
mapped to IP addresses. To map domain names to IP addresses, you must first identify the hostnames, specify the name server
that is present on your network, and enable the DNS.
Default DNS Settings
Table 1. Default DNS Settings
Feature
Default Setting
DNS enable state
Enabled.
DNS default domain name
None configured.
DNS servers
No name server addresses are configured.
Login Banners
You can configure a
message-of-the-day (MOTD) and a login banner. The MOTD banner is displayed on
all connected terminals at login and is useful for sending messages that affect
all network users (such as impending system shutdowns).
The login banner is also displayed on all connected
terminals. It appears after the MOTD banner and before the login prompts.
Note
For complete syntax and usage information for the commands used in
this section, see the
Cisco IOS Configuration Fundamentals Command Reference, Release
12.4.
Default Banner Configuration
The MOTD and login banners are not configured.
MAC Address Table
The MAC address table
contains address information that the
switch uses to forward traffic between ports.
All MAC addresses in the address table are associated with one or more ports.
The address table includes these types of addresses:
Dynamic address—A
source MAC address that the
switch learns and then ages when it is not in
use.
Static address—A manually entered unicast
address that does not age and that is not lost when the
switch resets.
The address table lists the
destination MAC address, the associated VLAN ID, and port number associated
with the address and the type (static or dynamic).
Note
For complete syntax and usage information for the commands used in
this section, see the command reference for this release.
MAC Address Table Creation
With multiple MAC addresses supported on all ports, you can connect any port on the switch to other network devices. The switch provides dynamic addressing by learning the source address of packets it receives on each port and adding the address and
its associated port number to the address table. As devices are added or removed from the network, the switch updates the address table, adding new dynamic addresses and aging out those that are not in use.
The aging interval is globally configured. However, the switch maintains an address table for each VLAN, and STP can accelerate the aging interval on a per-VLAN basis.
The switch sends packets between any combination of ports, based on the destination address of the received packet. Using the MAC address
table, the switch forwards the packet only to the port associated with the destination address. If the destination address is on the port that
sent the packet, the packet is filtered and not forwarded. The switch always uses the store-and-forward method: complete packets are stored and checked for errors before transmission.
MAC Addresses and VLANs
All addresses are associated
with a VLAN. An address can exist in more than one VLAN and have different
destinations in each. Unicast addresses, for example, could be forwarded to
port 1 in VLAN 1 and ports 9, 10, and 1 in VLAN 5.
Each VLAN maintains its own
logical address table. A known address in one VLAN is unknown in another until
it is learned or statically associated with a port in the other VLAN.
MAC Addresses and
Switch Stacks
The MAC address tables on all
stack members are synchronized. At any given time, each stack member has the
same copy of the address tables for each VLAN. When an address ages out, the
address is removed from the address tables on all stack members. When a
Switch
joins a switch stack, that
Switch
receives the addresses for each VLAN learned on the other stack members. When a
stack member leaves the switch stack, the remaining stack members age out or
remove all addresses learned by the former stack member.
Default MAC Address Table Settings
The following table shows the default settings for the MAC address table.
Table 2. Default Settings for the MAC Address
Feature
Default Setting
Aging time
300 seconds
Dynamic addresses
Automatically learned
Static addresses
None configured
ARP Table
Management
To
communicate with a device (over Ethernet, for example), the software first must
learn the 48-bit MAC address or the local data link address of that device. The
process of learning the local data link address from an IP address is called
address resolution.
The Address Resolution Protocol (ARP)
associates a host IP address with the corresponding media or MAC addresses and
the VLAN ID. Using an IP address, ARP finds the associated MAC address. When a
MAC address is found, the IP-MAC address association is stored in an ARP cache
for rapid retrieval. Then the IP datagram is encapsulated in a link-layer frame
and sent over the network. Encapsulation of IP datagrams and ARP requests and
replies on IEEE 802 networks other than Ethernet is specified by the Subnetwork
Access Protocol (SNAP). By default, standard Ethernet-style ARP encapsulation
(represented by the
arpa keyword) is enabled on the IP interface.
ARP entries added manually to
the table do not age and must be manually removed.
For CLI procedures, see the Cisco IOS Release 12.4 documentation on
Cisco.com.
How to Administer the Switch
Configuring the Time and Date Manually
System time remains accurate through restarts and reboot,
however, you can manually configure the time and date after the system is
restarted.
We recommend that you use manual configuration only when
necessary. If you have an outside source to which the
switch
can synchronize, you do not need to manually set the system clock.
Note
You must reconfigure this
setting if you have manually configured the system clock before the
active switch fails and a
different stack member assumes the role of
active switch.
Setting the System Clock
If you have an outside source
on the network that provides time services, such as an NTP server, you do not
need to manually set the system clock.
Follow these steps
to set the system clock:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
Use one of the following:
clock set
hh:mm:ss
day month year
clock
set hh:mm:ss month
day year
Example:
Switch# clock set 13:32:00 23 March 2013
Manually set the
system clock using one of these formats:
hh:mm:ss—Specifies the time in hours (24-hour
format), minutes, and seconds. The time specified is relative to the configured
time zone.
day—Specifies
the day by date in the month.
month—Specifies
the month by name.
year—Specifies the year (no abbreviation).
Configuring the Time Zone
Follow these steps to
manually configure the time zone:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters the global
configuration mode.
Step 3
clock timezonezone hours-offset [minutes-offset]
Example:
Switch(config)# clock timezone AST -3 30
Sets the time
zone.
Internal time is
kept in Coordinated Universal Time (UTC), so this command is used only for
display purposes and when the time is manually set.
zone—Enters the
name of the time zone to be displayed when standard time is in effect. The
default is UTC.
hours-offset—Enters the hours offset from UTC.
(Optional)
minutes-offset—Enters the minutes offset from UTC.
This available where the local time zone is a percentage of an hour different
from UTC.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring Summer Time (Daylight Saving Time)
To configure summer time
(daylight saving time) in areas where it starts and ends on a particular day of
the week each year, perform this task:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters the global
configuration mode.
Step 3
clock summer-timezonedatedate month year hh:mm date
month year hh:mm [offset]]
Example:
Switch(config)# clock summer-time PDT date
10 March 2013 2:00 3 November 2013 2:00
Configures
summer time to start and end on specified days every year.
Step 4
clock summer-timezonerecurring [week day month hh:mm week day month hh:mm [offset]]
Example:
Switch(config)# clock summer-time
PDT recurring 10 March 2013 2:00 3 November 2013 2:00
Configures summer
time to start and end on the specified days every year. All times are relative
to the local time zone. The start time is relative to standard time.
The end time is
relative to summer time. Summer time is disabled by default. If you specify
clock summer-timezonerecurring
without parameters, the summer time rules default to the United States rules.
If the starting
month is after the ending month, the system assumes that you are in the
southern hemisphere.
zone—Specifies the name of the time zone (for
example, PDT) to be displayed when summer time is in effect.
(Optional)
week— Specifies
the week of the month (1 to 4,
first, or
last).
(Optional)
day—Specifies
the day of the week (Sunday, Monday...).
(Optional)
month—Specifies
the month (January, February...).
(Optional)
hh:mm—Specifies the time (24-hour format) in hours
and minutes.
(Optional)
offset—Specifies the number of minutes to add
during summer time. The default is 60.
Step 5
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 6
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 7
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Follow these steps if summer time in your area does not follow a
recurring pattern (configure the exact date and time of the next summer time
events):
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters the global
configuration mode.
Step 3
clock summer-timezonedate[
month date year hh:mm month
date year hh:mm [offset]] orclock summer-timezonedate [date month year hh:mm date month year
hh:mm [offset]]
Configures summer time to start on the first date and end on the
second date.
Summer time is disabled by default.
For
zone, specify the name of the time
zone (for example, PDT) to be displayed when summer time is in effect.
(Optional) For
week, specify the week of the month
(1 to 5 or last).
(Optional) For
day, specify the day of the week
(Sunday, Monday...).
(Optional) For
month, specify the month (January,
February...).
(Optional) For
hh:mm, specify the time (24-hour
format) in hours and minutes.
(Optional) For
offset, specify the number of
minutes to add during summer time. The default is 60.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring a System Name
Follow these steps to
manually configure a system name:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters the global
configuration mode.
Step 3
hostnamename
Example:
Switch(config)# hostname
remote-users
Configures a
system name. When you set the system name, it is also used as the system
prompt.
The default
setting is
Switch.
The name must
follow the rules for ARPANET hostnames. They must start with a letter, end with
a letter or digit, and have as interior characters only letters, digits, and
hyphens. Names can be up to 63 characters.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Setting Up DNS
If you use the
switch IP address as its hostname, the IP
address is used and no DNS query occurs. If you configure a hostname that
contains no periods (.), a period followed by the default domain name is
appended to the hostname before the DNS query is made to map the name to an IP
address. The default domain name is the value set by the
ip domain-name global configuration command. If
there is a period (.) in the hostname, the Cisco IOS software looks up the IP
address without appending any default domain name to the hostname.
Follow these steps
to set up your switch to use the DNS:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters the global
configuration mode.
Step 3
ip
domain-namename
Example:
Switch(config)# ip domain-name Cisco.com
Defines a default
domain name that the software uses to complete unqualified hostnames (names
without a dotted-decimal domain name).
Do not include the
initial period that separates an unqualified name from the domain name.
At boot time, no
domain name is configured; however, if the
switch configuration comes from a BOOTP or
Dynamic Host Configuration Protocol (DHCP) server, then the default domain name
might be set by the BOOTP or DHCP server (if the servers were configured with
this information).
Step 4
ip name-serverserver-address1 [server-address2 ... server-address6]
Example:
Switch(config)# ip
name-server 192.168.1.100
192.168.1.200 192.168.1.300
Specifies the
address of one or more name servers to use for name and address resolution.
You can specify up
to six name servers. Separate each server address with a space. The first
server specified is the primary server. The
switch sends DNS queries to the primary
server first. If that query fails, the backup servers are queried.
Step 5
ip domain-lookup [nsap |
source-interfaceinterface]
Example:
Switch(config)# ip domain-lookup
(Optional) Enables
DNS-based hostname-to-address translation on your
switch. This feature is enabled by default.
If your network
devices require connectivity with devices in networks for which you do not
control name assignment, you can dynamically assign device names that uniquely
identify your devices by using the global Internet naming scheme (DNS).
Step 6
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 7
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 8
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring a Message-of-the-Day Login Banner
You can create a single or
multiline message banner that appears on the screen when someone logs in to the
switch
Follow these steps
to configure a MOTD login banner:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters the global
configuration mode.
Step 3
banner motdcmessage c
Example:
Switch(config)# banner motd #
This is a secure site. Only
authorized users are allowed.
For access, contact technical
support.
#
Specifies the
message of the day.
c—Enters the
delimiting character of your choice, for example, a pound sign (#), and press
the
Return key. The
delimiting character signifies the beginning and end of the banner text.
Characters after the ending delimiter are discarded.
message—Enters
a banner message up to 255 characters. You cannot use the delimiting character
in the message.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring a Login Banner
You can configure a login
banner to be displayed on all connected terminals. This banner appears after
the MOTD banner and before the login prompt.
Follow these steps
to configure a login banner:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters the global
configuration mode.
Step 3
banner loginc message c
Example:
Switch(config)# banner login $
Access for authorized users only.
Please enter your username and
password.
$
Specifies the
login message.
c— Enters the delimiting character of your choice,
for example, a pound sign (#), and press the
Return key. The
delimiting character signifies the beginning and end of the banner text.
Characters after the ending delimiter are discarded.
message—Enters a login message up to 255
characters. You cannot use the delimiting character in the message.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Managing the MAC Address Table
Changing the Address Aging Time
Follow these steps
to configure the dynamic address table aging time:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters the global
configuration mode.
Step 3
mac address-table
aging-time [0 |
10-1000000] [routed-mac |
vlanvlan-id]
Example:
Switch(config)# mac address-table
aging-time 500 vlan 2
Sets the length of
time that a dynamic entry remains in the MAC address table after the entry is
used or updated.
The range is 10 to
1000000 seconds. The default is 300. You can also enter 0, which disables
aging. Static address entries are never aged or removed from the table.
vlan-id—Valid IDs are 1 to 4094.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring MAC Address Change Notification Traps
Follow these steps
to configure the switch to send MAC address change notification traps to an NMS
host:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
host-addr—Specifies the name or address of the
NMS.
traps (the default)—Sends SNMP traps to the host.
informs—Sends SNMP informs to the host.
version—Specifies the
SNMP version to support. Version 1, the default, is not available with informs.
community-string—Specifies the string to send with
the notification operation. Though you can set this string by using the
snmp-server host command, we recommend that you
define this string by using the
snmp-server community command before using the
snmp-server host command.
notification-type—Uses the
mac-notification keyword.
vrfvrf
instance name—Specifies the VPN routing/forwarding instance for
this host.
Enters the trap
interval time and the history table size.
(Optional)
intervalvalue—Specifies
the notification trap interval in seconds between each set of traps that are
generated to the NMS. The range is 0 to 2147483647 seconds; the default is 1
second.
(Optional)
history-sizevalue—Specifies
the maximum number of entries in the MAC notification history table. The range
is 0 to 500; the default is 1.
Step 7
interfaceinterface-id
Example:
Switch(config)# interface
gigabitethernet1/0/2
Enters interface
configuration mode, and specifies the Layer 2 interface on which to enable the
SNMP MAC address notification trap.
Enables the MAC
address change notification trap on the interface.
Enables the trap
when a MAC address is
added on this interface.
Enables the trap
when a MAC address is
removed from this interface.
Step 9
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 10
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 11
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring MAC Address Move Notification Traps
When you configure MAC-move
notification, an SNMP notification is generated and sent to the network
management system whenever a MAC address moves from one port to another within
the same VLAN.
Follow these steps to
configure the
switch to send MAC address-move notification
traps to an NMS host:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
host-addr—Specifies the name or address of the
NMS.
traps (the default)—Sends SNMP traps to the host.
informs—Sends SNMP informs to the host.
version—Specifies the
SNMP version to support. Version 1, the default, is not available with informs.
community-string—Specifies the string to send with
the notification operation. Though you can set this string by using the
snmp-server
host command, we recommend that you define this string by using
the
snmp-server
community command before using the
snmp-server
host command.
notification-type—Uses the
mac-notification keyword.
Enables the
switch to send MAC address move notification
traps to the NMS.
Step 5
mac address-table
notification mac-move
Example:
Switch(config)# mac address-table
notification mac-move
Enables the MAC
address move notification feature.
Step 6
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 7
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 8
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
What to do next
To disable MAC address-move notification traps, use the
no snmp-server enable traps mac-notification
move global configuration command. To disable the MAC
address-move notification feature, use the
no mac address-table notification mac-move
global configuration command.
You can verify your settings by entering the
show mac address-table notification mac-move
privileged EXEC commands.
Configuring MAC Threshold Notification Traps
When you configure MAC
threshold notification, an SNMP notification is generated and sent to the
network management system when a MAC address table threshold limit is reached
or exceeded.
Follow these steps to configure the switch to send MAC address table
threshold notification traps to an NMS host:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
host-addr—Specifies the name or address of the
NMS.
traps (the default)—Sends SNMP traps to the host.
informs—Sends SNMP informs to the host.
version—Specifies the
SNMP version to support. Version 1, the default, is not available with informs.
community-string—Specifies the string to send with
the notification operation. You can set this string by using the
snmp-server host command, but we recommend that
you define this string by using the
snmp-server community command before using the
snmp-server host command.
notification-type—Uses the
mac-notification keyword.
Enables MAC
threshold notification traps to the NMS.
Step 5
mac address-table
notification threshold
Example:
Switch(config)# mac address-table
notification threshold
Enables the MAC
address threshold notification feature.
Step 6
mac address-table
notification threshold [limitpercentage] | [intervaltime]
Example:
Switch(config)# mac address-table
notification threshold interval 123Switch(config)# mac address-table
notification threshold limit 78
Enters the
threshold value for the MAC address threshold usage monitoring.
(Optional)
limit
percentage—Specifies the percentage of the MAC
address table use; valid values are from 1 to 100 percent. The default is 50
percent.
(Optional)
interval
time—Specifies the time between notifications;
valid values are greater than or equal to 120 seconds. The default is 120
seconds.
Step 7
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 8
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 9
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Adding and Removing Static Address Entries
Follow these steps
to add a static address:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters the global
configuration mode.
Step 3
mac address-table
staticmac-addrvlanvlan-idinterfaceinterface-id
Example:
Switch(config)# mac address-table
static c2f3.220a.12f4 vlan 4 interface gigabitethernet 1/0/1
Adds a static
address to the MAC address table.
mac-addr—Specifies the destination MAC unicast
address to add to the address table. Packets with this destination address
received in the specified VLAN are forwarded to the specified interface.
vlan-id—Specifies the VLAN for which the packet
with the specified MAC address is received. Valid VLAN IDs are 1 to 4094.
interface-id—Specifies the interface to which the
received packet is forwarded. Valid interfaces include physical ports or port
channels. For static multicast addresses, you can enter multiple interface IDs.
For static unicast addresses, you can enter only one interface at a time, but
you can enter the command multiple times with the same MAC address and VLAN ID.
Step 4
end
Example:
Switch(config)# end
Returns to privileged EXEC mode. Alternatively, you can also press Ctrl-Z to exit global configuration mode.
Step 5
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Configuring Unicast MAC Address Filtering
Follow these steps
to configure the
Switch
to drop a source or destination unicast static address:
Procedure
Command or Action
Purpose
Step 1
enable
Example:
Switch> enable
Enables
privileged EXEC mode. Enter your password if prompted.
Step 2
configureterminal
Example:
Switch# configure terminal
Enters the global
configuration mode.
Step 3
mac address-table
staticmac-addrvlanvlan-iddrop
Example:
Switch(config)# mac address-table
static c2f3.220a.12f4 vlan 4 drop
Enables unicast
MAC address filtering and configure the
switch to drop a packet with the specified
source or destination unicast static address.
mac-addr—Specifies a source or destination unicast
MAC address (48-bit). Packets with this MAC address are dropped.
vlan-id—Specifies the VLAN for which the packet
with the specified MAC address is received. Valid VLAN IDs are 1 to 4094.
Step 4
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 5
show running-config
Example:
Switch# show running-config
Verifies your entries.
Step 6
copy running-config
startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries
in the configuration file.
Monitoring and Maintaining Administration of the Switch
Command
Purpose
clear mac address-table dynamic
Removes all dynamic entries.
clear mac address-table dynamic addressmac-address
Removes a specific MAC address.
clear mac address-table dynamic interface interface-id
Removes all addresses on the specified physical port or port channel.
clear mac address-table dynamic vlan vlan-id
Removes all addresses on a specified VLAN.
show clock [detail]
Displays the time and date configuration.
show ip igmp snooping groups
Displays the Layer 2 multicast entries for all VLANs or the specified VLAN.
show mac address-table addressmac-address
Displays MAC address table information for the specified MAC address.
show mac address-table aging-time
Displays the aging time in all VLANs or the specified VLAN.
show mac address-table count
Displays the number of addresses present in all VLANs or the specified VLAN.
show mac address-table dynamic
Displays only dynamic MAC address table entries.
show mac address-table interfaceinterface-name
Displays the MAC address table information for the specified interface.
show mac address-table move update
Displays the MAC address table move update information.
show mac address-table multicast
Displays a list of multicast MAC addresses.
show mac address-table notification {change | mac-move | threshold}
Displays the MAC notification parameters and history table.
show mac address-table secure
Displays the secure MAC addresses.
show mac address-table static
Displays only static MAC address table entries.
show mac address-table vlanvlan-id
Displays the MAC address table information for the specified VLAN.
Configuration Examples for Switch Administration
Example: Setting the System Clock
This example shows how to manually set the system clock:
Switch# clock set 13:32:00 23 July 2013
Examples: Configuring Summer Time
This example (for daylight savings time) shows how to specify that summer time starts on March 10 at 02:00 and ends on November
3 at 02:00:
Switch(config)# clock summer-time PDT recurring PST date
10 March 2013 2:00 3 November 2013 2:00
This example shows how to set summer time start and end dates:
Switch(config)#clock summer-time PST date
20 March 2013 2:00 20 November 2013 2:00
Example: Configuring a MOTD Banner
This example shows how to configure a MOTD banner by using the pound sign (#) symbol as the beginning and ending delimiter:
Switch(config)# banner motd #
This is a secure site. Only authorized users are allowed.
For access, contact technical support.
#
Switch(config)#
This example shows the banner that appears from the previous configuration:
Unix> telnet 192.0.2.15
Trying 192.0.2.15...
Connected to 192.0.2.15.
Escape character is '^]'.
This is a secure site. Only authorized users are allowed.
For access, contact technical support.
User Access Verification
Password:
Example: Configuring a Login Banner
This example shows how to configure a login banner by using the dollar sign ($) symbol as the beginning and ending delimiter:
Switch(config)# banner login $
Access for authorized users only. Please enter your username and password.
$
Switch(config)#
Example: Configuring MAC Address Change Notification Traps
This example shows how to specify 172.20.10.10 as the NMS, enable MAC address notification traps to the NMS, enable the MAC
address-change notification feature, set the interval time to 123 seconds, set the history-size to 100 entries, and enable
traps whenever a MAC address is added on the specified port:
Example: Configuring MAC Threshold Notification Traps
This example shows how to specify 172.20.10.10 as the NMS, enable the MAC address threshold notification feature, set the
interval time to 123 seconds, and set the limit to 78 per cent:
Switch(config)# snmp-server host 172.20.10.10 traps private mac-notificationSwitch(config)# snmp-server enable traps mac-notification thresholdSwitch(config)# mac address-table notification thresholdSwitch(config)# mac address-table notification threshold interval 123Switch(config)# mac address-table notification threshold limit 78
Example: Adding the Static Address to the MAC Address Table
This example shows how to add the static address c2f3.220a.12f4 to the MAC address table. When a packet is received in VLAN
4 with this MAC address as its destination address, the packet is forwarded to the specified port:
Note
You cannot associate the same static MAC address to multiple interfaces. If the command is executed again with a different
interface, the static MAC address is overwritten on the new interface.
Switch(config)# mac address-table static c2f3.220a.12f4 vlan 4 interface gigabitethernet1/1/1
Example: Configuring Unicast MAC Address Filtering
This example shows how to enable unicast MAC address filtering and how to configure drop packets that have a source or destination
address of c2f3.220a.12f4. When a packet is received in VLAN 4 with this MAC address as its source or destination, the packet
is dropped:
Switch(config)# mac address-table static c2f3.220a.12f4 vlan 4 drop
Additional References for Switch Administration
Related Documents
Related Topic
Document Title
System management commands
System Management Command Reference (Catalyst 3650 Switches)
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