Chapter 2) Implementing Data Center Switching Protocols Flashcards
Describe the function of Spanning Tree edge ports.
Edge ports in spanning tree connect directly to end hosts. These ports can be either an access port or trunk port, and immediately transition to the forwarding state.
Describe the function of Spanning Tree network ports.
Network ports are normally connected only to switches or bridges. Bridge assurance is enabled only on network ports.
Describe the function of Spanning tree normal ports.
Normal ports can be connected to either hosts, switches, or bridges. These ports function as normal spanning tree ports.
What is the default spanning tree port type?
The default spanning tree interface is a normal port.
What is the function of the STP Bridge Assurance extension?
Spanning tree Bridge Assurance is one of those features that help prevent bridging loops in Layer 2 networks. When a BPDU is not received on an interface for a certain period of time, the port is disabled until it receives BDPUs again.
What is the function of the STP BPDU Guard extension?
This extension disables ports that receive a BPDU frame; it is useful for edge ports that should never be connected to another switch.
What is the function of the STP BPDU Filtering extension?
This extension prevents the switch from sending or even receiving BPDUs on a specified edge port.
What is the function of the STP Loop Guard extension?
This extension protects against network interfaces that malfunction. Loop Guard is useful only in switched networks where devices are connected by point-to-point links.
What is the function of the STP Root Guard extension?
This extension prevents a port from becoming a root port or a blocked port.
What is the default mode of STP for Cisco Nexus Switches?
Rapid PVST+
When do designated and root ports generate a TC (Topology Change)?
When the interface fails to receive 3 consecutive BPDUs, or when the max age timer expires.
What is the role and value of the TC While timer?
The TC While timer is equivalent to the hello interval + 1 second. While the TC While timer is running, the interface continues to set the TC flag on all BPDUs sent on that port.
What are the 4 Rapid PVST+ and MST port states?
Blocking: The switch LAN port does not participate in frame forwarding.
Learning: The switch LAN port prepares to participate in frame forwarding.
Forwarding: The switch LAN port forwards frames.
Disabled: The switch LAN port does not participate in STP and does not forward frames.
What the SPT short & high path-costs for a 10 Mbps link?
Short Path: 100
Long Path: 2,000,000
What the SPT short & high path-costs for a 100 Mbps link?
Short Path: 19
Long Path: 200,000
What the SPT short & high path-costs for a 1 Gbps link?
Short Path: 4
Long Path: 20,000
What the SPT short & high path-costs for a 10 Gbps link?
Short Path: 2
Long Path: 2000
What is the default Rapid PVST+ port priority value?
Default is 128.
What is the range of Rapid PVST+ port priority values?
0 to 224, in increments of 32.
What is the only Rapid PVST+ extension that is enabled on Cisco NX-OS by default?
STP Bridge Assurance.
What are the maximum amount of interfaces that can be supported in a single port channel?
8 or 16, depending on the hardware and software support in Cisco NX-OS.
What are the types of port channels that are supported by Cisco NX-OS?
Static, or LACP (Link Aggregation Control Protocol).
PAgP (Port Aggregation Protocol) is not a supported mode in Cisco NX-OS.
What is the difference between A vPC (Virtual Port Channel) and a VSS link (Virtual Switch System)?
The key difference between a vPC and a VSS is that the VSS creates a single logical switch. This results in a single control plane for both management and configuration purposes. With vPCs, each Cisco Nexus switch (vPC) is managed and configured independently. A vPC allows the creation of Layer 2 port channels that span two switches.
Describe the function of a vPC peer-keepalive or fault-tolerant link.
A routed “link” (it is more accurate to say path) used to resolve dual-active scenarios in which the peer link connectivityis lost.