Cisco Catalyst 3750 Software Configuration Manual page 42

Features
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VLAN Features
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Layer 2 Virtual Private Network (VPN) Services
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Catalyst 3750 Metro Switch Software Configuration Guide
1-4
Optional spanning-tree features available in PVST+, rapid-PVST+, and MSTP mode:
– Port Fast for eliminating the forwarding delay by enabling a port to immediately transition from
the blocking state to the forwarding state
– BPDU guard for shutting down Port Fast-enabled ports that receive bridge protocol data units
(BPDUs)
– BPDU filtering for preventing a Port Fast-enabled port from sending or receiving BPDUs
– Root guard for preventing switches outside the network core from becoming the spanning-tree
root
– Loop guard for preventing alternate or root ports from becoming designated ports because of a
failure that leads to a unidirectional link
Equal-cost routing for link-level and switch-level redundancy
Support for up to 1005 VLANs for assigning users to VLANs associated with appropriate network
resources, traffic patterns, and bandwidth
Support for VLAN IDs in the full 1 to 4094 range allowed by the IEEE 802.1Q standard
VLAN Query Protocol (VQP) for dynamic VLAN membership
Inter-Switch Link (ISL) and IEEE 802.1Q trunking encapsulation on all ports for network moves,
adds, and changes; management and control of broadcast and multicast traffic; and network security
by establishing VLAN groups for high-security users and network resources
Dynamic Trunking Protocol (DTP) for negotiating trunking on a link between two devices and for
negotiating the type of trunking encapsulation (802.1Q or ISL) to be used
VLAN Trunking Protocol (VTP) and VTP pruning for reducing network traffic by restricting
flooded traffic to links destined for stations receiving the traffic
Voice VLAN for creating subnets for voice traffic from Cisco IP Phones
VLAN 1 minimization for reducing the risk of spanning-tree loops or storms by allowing VLAN 1
to be disabled on any individual VLAN trunk link. With this feature enabled, no user traffic is sent
or received on the trunk, but the switch CPU continues to send and receive control protocol frames.
VLAN mapping on enhanced-services (ES) ports to translate customer VLANs to service-provider
VLANs for transporting packets across the service-provider network without affecting the customer
VLAN IDs
Custom ethertype to enable the user to change the ethertype value on a port to any value to direct
the tagged and untagged traffic to different VLANs (ES ports only)
802.1Q tunneling so that customers with users at remote sites across a service-provider network can
keep VLANs segregated from other customers, and Layer 2 protocol tunneling to ensure that the
customer's network has complete STP, CDP, and VTP information about all users
Layer 2 protocol tunneling bypass feature to provide interoperability with third-party vendors
Intelligent 802.1Q tunneling QoS, the ability to copy the inner cost-of-service (CoS) value to the
outer CoS value for 802.1Q tunneling
Support for Ethernet over multiprotocol layer switching (EoMPLS) tunneling mechanism for
transporting Ethernet frames over a service-provider MPLS network
Chapter 1 Overview
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