1-5
Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 1 Overview
Features
Availability Features
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UniDirectional Link Detection (UDLD) and aggressive UDLD for detecting and disabling
unidirectional links on fiber-optic interfaces caused by incorrect fiber-optic wiring or port faults
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IEEE 802.1D Spanning Tree Protocol (STP) for redundant backbone connections and loop-free
networks. STP has these features:
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Up to 128 supported spanning-tree instances
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Per-VLAN spanning-tree plus (PVST+) for balancing load across VLANs
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Rapid PVST+ for balancing load across VLANs and providing rapid convergence of
spanning-tree instances
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IEEE 802.1s Multiple Spanning Tree Protocol (MSTP) for grouping VLANs into a spanning-tree
instance and for providing multiple forwarding paths for data traffic and load balancing and rapid
per-VLAN Spanning-Tree plus (rapid-PVST+) based on the IEEE 802.1w Rapid Spanning Tree
Protocol (RSTP) for rapid convergence of the spanning tree by immediately transitioning root and
designated ports to the forwarding state
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Optional spanning-tree features available in PVST+, rapid-PVST+, and MSTP modes:
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Port Fast for eliminating the forwarding delay by enabling a spanning-tree port to immediately
transition from the blocking state to the forwarding state
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Bridge protocol data unit (BPDU) guard for shutting down Port Fast-enabled ports that receive
BPDUs
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BPDU filtering for preventing a Port Fast-enabled ports from sending or receiving BPDUs
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Root guard for preventing switches outside the network core from becoming the spanning-tree
root
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Loop guard for preventing alternate or root ports from becoming designated ports because of a
failure that leads to a unidirectional link
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Flex Link Layer 2 interfaces to back up one another as an alternative to STP for basic link
redundancy in a nonloop network with preemptive switchover and bidirectional fast convergence,
also referred to as the MAC address-table move update feature
•
Flex Link Multicast Fast Convergence to reduce the multicast traffic convergence time after a Flex
Link failure
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Support for Resilient Ethernet Protocol (REP) for improved convergence times and network loop
prevention without the use of spanning tree
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Support for REP edge ports with the no-neighbor option when the neighbor port is not REP-capable
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HSRP for Layer 3 router redundancy
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Equal-cost routing for link-level and switch-level redundancy (requires metro IP access image)
VLAN Features
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Support for up to 4094 VLANs for assigning users to VLANs associated with appropriate network
resources, traffic patterns, and bandwidth
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Support for VLAN IDs in the full 1 to 4094 range allowed by the IEEE 802.1Q standard