10-4
Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
OL-13270-01
Chapter10 Configuring Interface Characteristics
Understanding Interface Types
traffic is forwarded to and from the trunk port for that VLAN. If VTP l ear ns of a new, enabled VLAN
that is not in the allowed list for a trunk port, the port does not become a member of the VLAN, and no
traffic for the VLAN is forwarded to or from the port.
For more information about trunk ports, see Chapter 1 2, “Configuring V LANs.”

Tunnel Ports

Tunnel ports are used in IEEE 802.1Q tunneling to segregate the traffic of customers in a
service-provider network from other customers who are using the sam e V LAN n um ber. You configure
an asymmetric link from a tunnel port on a service-provider edge switch to an IEEE 802.1Q trunk port
on the customer switch. Packets entering the tunnel port on the edge switch, already
IEEE802.1Q-tagged with the customer VLANs, are encapsulated with another layer of an IEEE 802.1Q
tag (called the metro tag), containing a VLAN ID unique in the service-provider network, for each
customer. The double-tagged packets go through the service-provider network keeping the original
customer VLANs separate from those of other customers. At the outbound interface, al so a tunnel port,
the metro tag is removed, and the original VLAN numbers from the customer network are retrieved.
Tunnel ports cannot be trunk ports or access ports and must belong to a VLAN unique to each cu stomer.
For more information about tunnel ports, see Chapter 16, “Configu ring IEEE 802.1Q and Layer 2
Protocol Tunneling.”
Routed Ports
A routed port is a physical port that acts like a port on a router; it does not have to be connected to a
router. A routed port is not associated with a particular VLAN, as is a n access port. A routed port behaves
like a regular router interface, except that it does not support VLAN subinterface s . R outed ports can be
configured with a Layer 3 routing protocol. A routed port is a Layer 3 interface only and does not supp ort
Layer 2 protocols, such as DTP and STP.
Configure routed ports by putting the interface into Layer 3 mode with the no switchport interface
configuration command. Then assign an IP address to the port, enabl e ro ut ing, and assi gn rout ing
protocol characteristics by using the ip routing and router protocol global configuration commands.
Note Entering a no switchport interface configuration command shuts down the interface and then re-enables
it, which might generate messages on the device to which the interface is connected. When you put an
interface that is in Layer 2 mode into Layer 3 mode, the previous configuration information related to
the affected interface might be lost.
The number of routed ports that you can configure is not limited by software. However, the
interrelationship between this number and the number of other f eatur es b ein g c onfigure d mig ht i mp act
CPU performance because of hardware limitations. See the “Configuring Layer 3 Int erfaces” section on
page 10-22 for information about what happens when hardwa re r e sour ce l im ita tions ar e rea ched.
For more information about IP unicast and multicast routing and r outing pr otoc ols, se e Cha pter 38,
“Configuring IP Unicast Routing” and Chapter 44, “Configuring IP Multicast Routing.”
Note The IP base feature set supports static routing and the R outi ng Infor ma tion Prot ocol (RI P). For fu ll
Layer3 routing or for fallback bridging, you must enable the IP services feature set on the standalone
switch or the stack master.