4 - RSTP and EtherChannel Configuration Flashcards
What does the term access switch to refer to?
Switches that connect to endpoint devices
What does the term distribution switch refer to?
Switches that do NOT connect to end points, but connect to each access switch
What is PVST+?
Cisco proprietary Per VLAN STP protocol that creates one STP instance per VLAN
What is RPVST+?
Cisco proprietary Per VLAN RSTP protocol, including more features than the standardized RSTP
What is the IEEE equivalent of Cisco’s PVST+ / RPVST+?
Multiple Spanning Tree Protocol (MSTP)
True/False: Cisco Switches support standard STP/RSTP and PVST+ and RPVST+
False. They do not support single tree (CST)
What is the config parameter for PVST+?
pvst
What is the config parameter for RPVST+?
rapid-pvst
What is the config parameter for MSTP?
mst
What is the difference between the BID and priority field in normal STP/RSTP compared with PVST+/RPVST+?
The original priority field of 2 bytes is now divided into 4 bits of priority and a 12 bit subfield (System ID extension) aka VLAN ID
What values are valid for the PVST+/RPVST+ 4 bit priority field?
Still 0-65535 but in multiples of 4096
What’s another way to conveniently configure a switch priority for a given VLAN without setting a value manually?
spanning-tree vlan 2 root primary
OR
spanning-tree vlan 2 root secondary
How does RSTP differ from RPVST+ with regards to transmission of BPDUs?
RPVST+ sends one set of messages for each VLAN, opposed to one set of messages overall
What does RSTP do differently from RPVST+ with regards to transmission of messages on VLAN trunk links?
RSTP sends messages in native VLAN with no header/tag. RPVST+ sends each VLANs messages inside that VLAN with the 802.1Q header listing that VLAN
What is the TLV and what is it used for?
Type Length Value. RPVST+ adds to the BPDU that identifies the VLAN ID.
Standard RSTP doesn’t do this because it ignores VLANs
How do you set the switch priority for a given VLAN?
spanning-tree vlan 1 priority 4096
How do you configure a switch’s STP/RSTP port cost for a given port?
Interface subcommand:
spanning-tree vlan 1 cost x
What configuration command is used to configure EtherChannels on each physical interface?
channel-group
What is the difference between an EtherChannel and a PortChannel?
Nothing. They are the same thing
What is the difference between an EtherChannel and a Channel-group?
Nothing. They are the same thing
What command is used to show the status of an EtherChannel/Channel-group/Port Channel?
show etherchannel
What commands would you use to manually configure an EtherChannel?
int f0/1
channel-group 10 mode on
int f0/2
channel-group 10 mode on
How do you show a summary of a given EtherChannel?
show etherchannel 1 summary
How do Dynamic EtherChannel configuration protocols work?
Switches can use the protocol for particular channel-group number to exchange messages with neighboring switch to discover if configuration settings pass all checks. If so link is added to the EtherChannel and used.
