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and is
sent to Switch E. Switch E examines the ISL header and determines that the frame is intended for VLAN 20 and
sends the
frame out on port 2/2 to Switch A. Switch A examines the ISL header to determine the VLAN for which the frame is
destined,
removes the header, and switches it to all ports in VLAN 20 (if the frame is broadcast or multicast) or to port 2/4 if
the frame is
a unicast.
Configuring the Switches
When a Catalyst 5000 switch first starts up, the following defaults are set:
The console port is set to 9600 baud, 8 data bits, no parity, and 1 stop bit. If you want to change the baud rate, use
the
set system baud command.
The Cisco Discovery Protocol (CDP) is enabled on every port to send a CDP message every 60 seconds. If you
want
to disable CDP on ports that do not have a Cisco device, use the set cdp disable command.
The following Simple Network Management Protocol (SNMP) community strings are defined:
"public" for the read-only access type
"private" for the read-write access type
"secret" for the read-write-all access type
If you want to set other SNMP community strings, use the set snmp community command.
All modules and all ports are enabled. To disable a module, use the set module disable command, and to disable a
port,
use the set port disable command.
All 10-Mbps Ethernet ports are set to half duplex. Use the set port duplex command to set a port to full duplex.
When you first start up a switch, you should set some values that apply to the switch as a whole. For example, you
might enter
the following commands at the console port of Switch A:
set system contact Terry Moran
set system location Norwich
set system name SwitchA
set time fri 9/15/95 14:08:34
set prompt SwitchA>
set password
set enablepass
set interface sc0 131.108.40.1
The set system contact command establishes "Terry Moran" as the person to contact for system administration. The
set system
name establishes "SwitchA" as the name of this switch. The set time command sets the current time, using a 24-hour
clock
format. The set prompt command sets the prompt to "SwitchA>". The default prompt is "Console>".
The set password command sets password protection for the administrative interface in normal mode. When you
enter the set
password command, the switch prompts you to enter a password and then prompts you to reenter the password.
The set enablepass command sets password protection for the administrative interface in privileged mode. When you
enter the
set enablepass command, the switch prompts you to enter a password and then prompts you to reenter the password.
The set interface command assigns an IP address and netmask to interface sc0. After you make this assignment, you
can Telnet
to the switch to perform administrative tasks. The switch supports up to eight simultaneous Telnet connections.
Alternatively,
you can use the set interface command to enable a Serial Line Interface Protocol (SLIP) connection on the console
interface
(sl0).
Configuring VLANs on Switch A
The following commands configure VLANs 10 and 20 on Switch A:
set vlan 10 2/1,2/2
set vlan 20 2/4
set trunk 1/1 10,20
The first set vlan command creates VLAN 10 and assigns ports 1 and 2 in slot 2 to it. The second set vlan command
creates
VLAN 20 and assigns port 4 in slot 2 to it.
The set trunk command configures port 1 in slot 1 as a trunk and adds VLANs 10 and 20 to it. Trunks are used for
Fast
Ethernet connections between switches. When a port is configured as a trunk, it runs in ISL mode. To detect and
break loops,
trunks use the spanning-tree protocol on all VLANs that are carried across the trunk.
Configuring VLANs on Switch B
The following commands configure VLANs 10 and 20 on Switch B:
set vlan 10 2/2
set vlan 20 2/1,2/3
set trunk 1/1 10,20
The first set vlan command creates VLAN 10 and assigns port 2 in slot 2 to it. The second set vlan command creates
VLAN
20 and assigns ports 1 and 3 in slot 2 to it. The set trunk command configures port 1 in slot 1 as a trunk and adds
VLANs 10
and 20 to it.
Configuring VLANs on Switch E
The following commands configure VLANs 10 and 20 on Switch E:
set trunk 2/1 10,20
set trunk 2/2 10,20
The first set trunk command configures port 1 in slot 2 as a trunk and adds VLANs 10 and 20 to it. This trunk is used
to
communicate with Switch B. The second set trunk command configures port 2 in slot 2 as a trunk and adds VLANs
10 and 20
to it. This trunk is used to communicate with Switch A.
Summary
LAN switching technology improves the performance of traditional Ethernet, FDDI, and Token Ring technologies
without
requiring costly wiring upgrades or time-consuming host reconfiguration. The low price per port allows the
deployment of LAN
switches so that they decrease segment size and increase available bandwidth. VLANs make it possible to extend the
benefit of
switching over a network of LAN switches and other switching devices. [ Pobierz całość w formacie PDF ]

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