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This example illustrates inter-VLAN
routing with Catalyst 5000 and 4000 Series Layer 3 switches used at
the distribution layer while using a Layer 2 switch in the core.
This example is fairly
straightforward and designed to illustrate all necessary commands to
facilitate inter-VLAN routing. The routing protocol is EIGRP and the
networks used are from the 192.168.x.x pool. The exact allocation of
addresses per VLAN are shown in the top left part of the Figure.
The connections between the
distribution switches and the core switch are both configured as
trunk links. The Catalyst 5000 Series Switch is using ISL while the
Catalyst 4000 Series Switch is using 802.1Q.
The VTP domain being used is Cisco
and the VTP server is the Catalyst 5000 Series Switch, while the
other switches are acting as Virtual Trunking Protocol (VTP)
clients. You can verify this information by examining the
configuration of CAT5505 in the #vtp section. You can also verify
that CAT4000 is a vtp client by examining the #vtp section of its
configuration. Remember, this must be done before you can configure
VLANS.
The following outlines a
configuration checklist:
CAT5505
- Enable interface sc0 using the set
interface sc0 up command.
- Assign an IP address to the sc0
interface (192.168.1.3).
- Set any relevant passwords.
- Set the VTP domain and specify the
switch as a VTP server.
- Configure the hostname (we could
do this at any point).
- By default, VLAN 1 is enabled on
all interfaces. So we created VLAN 10 on 2/4-5, VLAN 100 on 2/1
and VLAN 200 on 2/2.
- FastEthernet interface 2/3 was
then configured as a trunk link permitting all VLANs.
- Now we can take a look at the RSM
(Bucs) on CAT5505, we reached it by issuing the command session
3.
- Our first step on the RSM was to
create the logical interfaces VLAN 1, VLAN 10, VLAN 100 and VLAN
200. We also gave each interface an IP address in its respective
pool of addresses.
- The only other configuration
needed here was to enable the EIGRP routing protocol and
advertise the appropriate addresses.
The CAT 4000 followed the same
procedure except the commands for Layer 3 services are different.
The Port Channel you see configured in the #port channel section is
actually representing a connection to the backplane of the switch.
This is basically a port channel consisting of 2 gigabit Ethernet
links.
On the Layer 3 card, you can see the
difference in the command structure. While there are several ways to
configure this card, channeling the internal gigabit slots is
preferred. As you can see, each VLAN is represented as a
subinterface of the Gigabit 3 and 4 port channel. Just like the 5000
series, we have to assign each interface an address. However, we
must also specify the encapsulation type. Lastly, we enabled EIGRP
again.
The other variable on the CAT4000 is
the trunking protocol. In this case, the trunk link (Fast 2/3) is
using the IEEE 802.1Q encapsulation. This can be verified in the
switch configuration under the #vtp header.
On the Core 1 switch, which is a 2900
series layer 2 switch, there was not much to configure. As you can
see we simply configured interfaces FastEthernet 0/2 and 0/3 to be
trunk links. Lastly, for management purposes, we gave VLAN 1 an IP
address in the VLAN 1 pool.
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Interactive
Lab Activity (Flash,
295 kB) |
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In this
activity, you will learn how to configure the Catalyst 4000 switch
and route processor to perform inter-VLAN
routing. |
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Lab
Activity |
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In
this lab activity, you will learn how to
configure an IP helper address pointing DHCP
enabled router. |
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