VLAN Management
Overview
Cisco 350XG & 550XG Series 10G Stackable Managed Switches
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The IP router might be a traditional router, where each of its interfaces connects to
only one VLAN. Traffic to and from a traditional IP router must be VLAN untagged.
The IP router can be a VLAN-aware router, where each of its interfaces can
connect to one or more VLANs. Traffic to and from a VLAN-aware IP router can be
VLAN tagged or untagged.
Adjacent VLAN-aware devices exchange VLAN information with each other by
using Generic VLAN Registration Protocol (GVRP). As a result, VLAN information is
propagated through a bridged network.
VLANs on a device can be created statically or dynamically, based on the GVRP
information exchanged by devices. A VLAN can be static or dynamic (from GVRP),
but not both. For more information about GVRP, refer to the GVRP Settings section.
Some VLANs can have additional roles, including:
•
Voice VLAN: For more information refer to the
section.
•
Guest VLAN: Set in the
.
•
Default VLAN: VLAN1.
•
Management VLAN (in Layer 2-system-mode systems): For more
information refer to the Layer 2 IP Addressing section.
QinQ
QinQ provides isolation between service provider networks and customers'
networks. The device is a provider bridge that supports port-based c-tagged
service interface.
With QinQ, the device adds an ID tag known as Service Tag (S-tag) to forward
packets into the provider network. The S-tag is used to segregate traffic between
various customers, while preserving the customer VLAN tags.
Customer traffic is encapsulated with an S-tag with TPID 0x8100, regardless of
whether it was originally c-tagged or untagged. The S-tag enables this traffic to be
treated as an aggregate within a provider bridge network, where the bridging is
based on the S-tag VID (S-VID) only.
The S-Tag is preserved while traffic is forwarded through the network service
provider's infrastructure, and is later removed by an egress device.
An additional benefit of QinQ is that there is no need to configure customers' edge
devices.
