4 - RSTP and EtherChannel Configuration Flashcards

1
Q

What does the term access switch to refer to?

A

Switches that connect to endpoint devices

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2
Q

What does the term distribution switch refer to?

A

Switches that do NOT connect to end points, but connect to each access switch

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3
Q

What is PVST+?

A

Cisco proprietary Per VLAN STP protocol that creates one STP instance per VLAN

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4
Q

What is RPVST+?

A

Cisco proprietary Per VLAN RSTP protocol, including more features than the standardized RSTP

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5
Q

What is the IEEE equivalent of Cisco’s PVST+ / RPVST+?

A

Multiple Spanning Tree Protocol (MSTP)

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6
Q

True/False: Cisco Switches support standard STP/RSTP and PVST+ and RPVST+

A

False. They do not support single tree (CST)

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7
Q

What is the config parameter for PVST+?

A

pvst

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8
Q

What is the config parameter for RPVST+?

A

rapid-pvst

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9
Q

What is the config parameter for MSTP?

A

mst

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10
Q

What is the difference between the BID and priority field in normal STP/RSTP compared with PVST+/RPVST+?

A

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

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11
Q

What values are valid for the PVST+/RPVST+ 4 bit priority field?

A

Still 0-65535 but in multiples of 4096

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12
Q

What’s another way to conveniently configure a switch priority for a given VLAN without setting a value manually?

A

spanning-tree vlan 2 root primary
OR
spanning-tree vlan 2 root secondary

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13
Q

How does RSTP differ from RPVST+ with regards to transmission of BPDUs?

A

RPVST+ sends one set of messages for each VLAN, opposed to one set of messages overall

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14
Q

What does RSTP do differently from RPVST+ with regards to transmission of messages on VLAN trunk links?

A

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

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15
Q

What is the TLV and what is it used for?

A

Type Length Value. RPVST+ adds to the BPDU that identifies the VLAN ID.

Standard RSTP doesn’t do this because it ignores VLANs

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16
Q

How do you set the switch priority for a given VLAN?

A

spanning-tree vlan 1 priority 4096

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17
Q

How do you configure a switch’s STP/RSTP port cost for a given port?

A

Interface subcommand:

spanning-tree vlan 1 cost x

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18
Q

What configuration command is used to configure EtherChannels on each physical interface?

A

channel-group

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19
Q

What is the difference between an EtherChannel and a PortChannel?

A

Nothing. They are the same thing

20
Q

What is the difference between an EtherChannel and a Channel-group?

A

Nothing. They are the same thing

21
Q

What command is used to show the status of an EtherChannel/Channel-group/Port Channel?

A

show etherchannel

22
Q

What commands would you use to manually configure an EtherChannel?

A

int f0/1
channel-group 10 mode on
int f0/2
channel-group 10 mode on

23
Q

How do you show a summary of a given EtherChannel?

A

show etherchannel 1 summary

24
Q

How do Dynamic EtherChannel configuration protocols work?

A

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.

25
Q

What are two common protocols for dynamic EtherChannel configuration?

A

PAgP(Port Aggregation Protocol) - Cisco

LACP (Link Aggregation Control Protocol) - IEEE

26
Q

How many EtherChannel links does LACP support?

A

16

27
Q

How many EtherChannel links does PAgP support?

A

8

28
Q

What two mode keywords are used when enabling PAgP?

A

desirable and auto

29
Q

What two mode keywords are used when enabling LACP?

A

active and passive

30
Q

Can you use the on keyword to configure LACP or PAgP?

A

No. This uses neither of those protocols

31
Q

How would you configure PAgP on two switches?

A

SW1: channel-group 1 mode desirable
SW2: channel-group 1 mode auto | desirable

32
Q

How would you configure LACP on two switches?

A

SW1: channel-group 1 mode active
SW2: channel-group 1 mode active | passive

33
Q

What command would you use to verify an EtherChannel configuration?

A

show etherchannel 1 port-channel

34
Q

What items must match on ALL ports participating in an EtherChannel?

A
  • speed
  • duplex
  • operational access mode (ALL trunk or ALL access)
  • access VLAN
  • OR allowed VLAN list
  • OR native VLAN
  • STP interface settings
35
Q

How do switches negotiate and check settings for EtherChannel between themselves and other switches?

A

Either use PAgP / LACP if already in use or CDP if using manual configuration

36
Q

What would happen in an EtherChannel with mismatched STP cost?

A

It would fail

37
Q

What command is used to configure EtherChannel load distribution?

A

Global command: port-channel load-balance

38
Q

What values does EtherChannel load distribution use to make choices?

A

Various numeric values found in Layer 2, 3, and 4 headers

39
Q

What are some common goals of using different EtherChannel load distribution methods?

A
  • Cause all messages in single app flow to use the same link in a channel (prevent inadvertent reordering)
  • Use all active links in EtherChannel adjusting to addition and removal of active links over time
  • Balance traffic across active links
40
Q

What command is used to show EtherChannel load balancing configuration?

A

show etherchannel load-balance

41
Q

How would you show how a switch would distribute traffic on an EtherChannel?

A

test etherchannel load-balance interface po1 mac …

42
Q

What standard is 802.w?

A

RSTP

43
Q

What IEEE standard is 802.1D?

A

STP

44
Q

What IEEE standard is MST?

A

802.1s

45
Q

How do you configure etherchannel

A

Router# configure terminal
Router(config)# interface port-channel 1
Router(config-if)# ip address 10.0.0.1 255.255.255.0
Router(config-if)# end
Router(config)# interface range gigabitEthernet 0/0-1
Router(config-if)# channel-group 1
Router(config-if)# end