InterVLAN Acquisition Configuration
This area presents a added abundant attending at configuring interVLAN acquisition application both
external and chip Cisco avenue processors. Routing, in itself, is a circuitous and extensive
topic. Alone the basal acquisition agreement agreement is presented here, to accommodate simple but
functional acquisition amid VLANs. If you charge added advice on the assorted routing
protocols, accredit to the Interconnecting Cisco Arrangement Accessories (ICND) and Building Scalable
Cisco Networks (BSCN) courses or advance books and the Cisco CCNP Acquisition Exam
Certification Guide.
Accessing the Avenue Processor
To activate interVLAN acquisition configuration, the avenue processor charge aboriginal be accessed. On an
external router, a terminal adversary affairs can be acclimated to affix anon with the console
port. If some IP connectivity is already accessible on the router, a telnet affair can be opened
to the router.
An chip or centralized avenue processor charge aboriginal be amid in the about-face chassis. Use the
show bore command on a Catalyst about-face to get a advertisement of the installed modules (see
Example 7-1). The avenue processor is the bore with Avenue About-face in the Module-Type field.
For example, an RSM is installed in aperture 8 in this Catalyst switch.
InterVLAN Acquisition Agreement 251
Other chip avenue processors can be amid in the aforementioned fashion. An RSFC bore in a
Catalyst 5000 about-face will be listed as Avenue About-face Feature Card. A MSM bore (now
obsolete) in a Catalyst 6000 about-face will be listed as Multilayer About-face Module.
To authorize a terminal affair with the chip avenue processor, use the affair Catalyst
switch command with the bore cardinal as an argument. For example, if an RSM is located
in aperture 5, again affair 5 will accompany up a new affair with a user interface to the RSM. Note that
the chip avenue processors run Cisco IOS. Therefore, the user interface and command set
may be altered from that of the host switch. The affair command about starts a Telnet
session with the avenue processor. By application the avenue IOS command, the router affair is
terminated and the about-face affair is resumed.
For approaching identification and readability, you should accredit a hostname to the avenue processor at
this point. The hostname name command assigns the cord name as the router’s hostname and
also as its command band prompt.
Establishing VLAN Connectivity
Next, the avenue processor will charge to accept its interfaces configured to abutment connectivity to
the all-important VLANs. This is able application interfaces and commands that are altered to
the avenue processor hardware. The afterward sections present this advice for anniversary blazon of
link amid the avenue processor and switches.
Establishing VLAN Connectivity with Concrete Interfaces
External routers are affiliated to switches application acceptable LAN media links. For example,
Ethernet, Fast Ethernet, Gigabit Ethernet, or Token Ring could be used. Here, individual
physical router interfaces are configured for a distinct arrangement anniversary and affiliated to non-trunk
switch ports configured for VLAN membership. By way of the concrete connection, the router
interface inherits the VLAN character of the about-face port.
Example 7-1 appearance bore Command Output Displays a Advertisement of Installed Modules on a Catalyst Switch
Switch (enable) appearance module
Mod Module-Name Ports Module-Type Model Serial-Num Status
--- ------------------- ----- --------------------- --------- --------- -------
1 2 1000BaseSX Supervisor WS-X5530 010849466 ok
2 24 10/100BaseTX Ethernet WS-X5224 010445883 ok
3 24 10/100BaseTX Ethernet WS-X5224 010433970 ok
4 24 10/100BaseTX Ethernet WS-X5224 010435124 ok
5 24 10/100BaseTX Ethernet WS-X5224 010432035 ok
7 24 10/100BaseTX Ethernet WS-X5224 010909044 ok
8 1 Avenue About-face WS-X5302 012766975 ok
9 2 SM OC-3 Dual-Phy ATM WS-X5157 010995049 ok
252 Chapter 7: InterVLAN Routing
To configure a concrete interface, admission the agreement approach and the interface configuration
mode. Again accredit a arrangement abode to the interface and accomplish abiding the interface is in
operation. The commands all-important for these operations are as follows:
Router# configure terminal
Router(config)# interface media module/port
Router(config-if)# description description-string
Router(config-if)# ip abode ip-addr subnet-mask
Router(config-if)# no shutdown
The interface is articular by its media type, module, and anchorage number. For example, a Fast
Ethernet interface on bore aperture 0 and anchorage 3 would be referenced as interface fastethernet 0/
3. A argument cord can be accustomed as a animadversion or description to added analyze the interface. A
network address, or an IP abode in this case, is assigned to the interface. Finally, the interface
is affected to be alive application the no abeyance command.
Establishing VLAN Connectivity with Block Links
When an alien router is affiliated to a about-face by a block link, the block charge be configured.
The concrete interface on the router charge be Fast Ethernet or Gigabit Ethernet to support
trunking and VLAN encapsulation. In addition, the concrete interface is articular with a slot
number and a above interface number. For example, a Fast Ethernet interface could be located
in aperture 3, anchorage 2 of the router—interface fastethernet 3/2.
Once trunking is enabled on the interface, anniversary VLAN in the block is represented by a
subinterface number. These numbers can be arbitrarily chosen, but charge be altered aural the
major interface number. Subinterface 1 in the antecedent archetype would be articular as
interface fastethernet 3/2.1.
For anniversary VLAN to be connected, trunking and VLAN encapsulation charge be configured on the
respective subinterface. Again the subinterface is assigned a arrangement address. The router
commands all-important for these accomplish are are as follows:
Router(config)# interface module/port.subinterface
Router(config-if)# encapsulation [isl | dot1q] vlan-number
Router(config-if)# ip abode ip-address subnet-mask
Once the subinterface has been identified, VLAN agreement takes abode with the
encapsulation command. Both IEEE 802.1Q and ISL trunking encapsulations are supported.
Notice that the subinterface is assigned to a specific VLAN with this command’s vlan-number
field. In this fashion, anniversary subinterface can be associated with a altered VLAN number.
Because a block articulation is actuality used, the VLAN numbers will bout on both the router and switch
ends.
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Establishing VLAN Connectivity with LANE
In some cases, an alien router charge be affiliated to campus switches via an ATM network.
LANE charge be used, and the router charge be able with an ATM Interface Processor, or
module, that supports LANE. Both routers and Catalyst about-face LANE modules run Cisco IOS,
so the commands acclimated to configure LANE are identical. Chapter 6 can be referenced for further
information on LANE.
LANE trunking is agnate to Ethernet trunking in two ways: a above interface is acclimated for
connectivity, and alone subinterfaces accord to distinct VLANs. On the above interface,
ATM is configured. Anniversary ATM subinterface is configured with a LEC per ELAN. Recall that
the LANE bore on a Catalyst about-face performs bridging amid the VLAN on the LAN side
and the ELAN on the ATM side. A router alone needs to avenue packets amid ELANs directly.
Assuming that the LECS, LES, and BUS abide on added arrangement devices, alone LECs charge to
be configured on the router. Agreement begins with the ATM interface:
Router(config)# interface atm module/port
Router(config-if)# no ip address
Router(config-if)# atm pvc 1 0 5 qsaal
Router(config-if)# atm pvc 2 0 16 ilmi
Router(config-if)# interface atm module/port.subinterface multipoint
Router(config-if)# ip abode ip-address subnet-mask
Router(config-if)# lane applicant ethernet elan-name
Router(config-if)# interface atm module/port.subinterface multipoint
Router(config-if)# ip abode ip-address subnet-mask
Router(config-if)# lane applicant ethernet elan-name
Router(config-if)# ...
The aboriginal command band begins agreement of the ATM above interface. Notice that this interface
does not accept a arrangement abode because subinterfaces accommodate all arrangement access. The atm
pvc curve configure abiding basic circuits (PVCs) for assorted aerial processes. The first
PVC is for the Q Signaling ATM Adaptation Layer (QSAAL)—(VPI/VCI 0/5)—which provides
the signaling agreement amenable for ambience up and disturbing bottomward switched basic circuits
(SVCs). The additional PVC is for Chip Local Management Interface (ILMI) (VPI/VCI 0/16),
which provides advice amid the ATM bend accessory and the ATM switches.
Then ATM subinterfaces are created one per ELAN. The subinterface cardinal is arbitrary, but
must be unique. Anniversary subinterface is assigned a arrangement abode to participate in the ELAN. In
this example, IP addresses are used. In reality, any baffled agreement arrangement abode (for
example, Internetwork Packet Exchange [IPX] and AppleTalk) can be used. Lastly, each
subinterface is assigned to the adapted ELAN by referencing the ELAN’s name.
NOTE For added advice about configuring the actual LANE components, see Chapter 6.
The IOS commands all-important for LANE agreement can be activate in the Cisco IOS Switching
Services Agreement Guide, beneath “LAN Emulation”: www.cisco.com/univercd/cc/td/doc/
product/software/ios121/121cgcr/switch_c/xcprt8/index.htm.
254 Chapter 7: InterVLAN Routing
Establishing VLAN Connectivity with Chip Acquisition Processors
Route processors centralized to a Catalyst about-face about accept no concrete interfaces to connect
and configure. Rather, these modules use centralized access into the switching backplane or
fabric. The blazon of affiliation is accompanying to the specific bore actuality used. However, the
configuration is basically the aforementioned as an alien router—interfaces are configured with
network addresses and some advertence to VLANs.
To activate configuration, the avenue processor bore charge be amid and a terminal session
opened. Use the appearance bore command to account the installed modules. Again use the session
module-number command to accessible a Telnet affair to the acquisition bore amid at slot
module-number. This command will accessible a affair to the IOS command band active on the
route processor module.
The RSM and RSFC modules in a Catalyst 5000 use basic VLAN interfaces to provide
connectivity to alone VLANs. These interfaces are configured with arrangement addresses (IP,
IPX, AppleTalk). The RSM and RSFC both accomplish access to the configured VLANs over
their centralized block ports to the about-face backplane. Use the afterward commands to configure the
VLAN interfaces:
Switch(enable) affair module-number
...
Router# configure terminal
Router(config)# interface vlan vlan-number
Router(config-if)# ip abode ip-address subnet-mask
Router(config-if)# no shutdown
Router(config-if)# interface vlan vlan-number
Router(config-if)# ip abode ip-address subnet-mask
Router(config-if)# no shutdown
...
The VLAN numbers acclimated in the interface vlan commands accord to the VLAN numbers
assigned to the assorted about-face ports. Afterwards a VLAN interface is configured, it charge be enabled
with the no abeyance command. Even admitting the interfaces are basic and accept no physical
link status, they are shut bottomward by absence afterwards antecedent configuration.