Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

myCCNP Switch 300-115 > Etherchannels > Flashcards

Etherchannels Flashcards

1
Q

What are etherchannels?

A

Logical bundlings of two to eight links between two switches.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does STP view etherchannels?

A

As a single port, no matter how many links make up the etherchannel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

In STP, how is the port cost of an etherchannel determined?

A

By the number and speed of the ports in the etherchannel. More, faster ports=lower port cost.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What action does STP take when a single port in an etherchannel goes down?

A

It increases the port cost for the etherchannel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Does the channel group number have to match between two switches?

A

No. It’s a local value.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the three variations of etherchannel?

A

LACP, PAgP, and static.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a port channel?

A

The logical representation of an etherchannel. It’s how etherchannels are referred to within CIOS syntax.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What command is used to configure a port channel?

A

From interface config: channel-group (#) mode ( )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is PAgP?

A

Port aggregation protocol. A Cisco proprietary etherchannel negotiation protocol.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is LACP?

A

Link aggregation control protocol. Industry standard etherchannel negotiation protocol.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a good show command to check the overall status of etherchannels on a switch?

A

Show etherchannel brief, or Show etherchannel summary.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does LACP use port priority for?

A

To determine which 8 of the total 16 allowed ports will be actively used in the etherchannel. Lower priority ports will be used.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a good command to check etherchannel relationship status?

A

Show LACP/PAgP neighbor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How many ports can be assigned to a LACP etherchannel?

A

16, but only 8 will be used, determined by priority.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the LACP port modes?

A

Active and passive.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the PAgP port modes?

A

Auto and desirable.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens if you make a change to an individual PAgP port?

A

The change will be made on all ports in the etherchannel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What criteria can be chosen for etherchannel load-distribution?

A

Source MAC, destination MAC, source & destination MAC, source IP, destination IP, source & destination IP, TCP/UDP source, TCP/UDP destination, TCP/UPD source & destination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Can load-distribution criteria be chosen on an etherchannel-by-etherchannel basis?

A

No, it can only be configured globally.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does etherchannel load-distribution work?

A

Values 0-7 are assigned equally among the etherchannel interfaces. Unique MAC/IPs (whatever you’re using for criteria) are mapped to these values, and in turn are assigned to an interface. This is NOT true load-balancing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How is etherchannel load-balancing different when using source & destination MAC/IP?

A

The XOR (exclusive-or) operation is used to map each unique combination of addresses to a port. This operation compares the last few bits of the source and destination address to determine it’s value, which is then mapped to a port.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe STP etherchannel misconfig guard.

A

STP etherchannel misconfig guard protects against loops caused by statically configured etherchannels that are not configured on both switches. If a misconfiguration is detected, the switch will be placed into err-disable state.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What command will change the etherchannel load-distribution criteria?

A

From global config, “port-channel load-balance ___”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What command will enable STP etherchannel misconfig guard?

A

From global config, “spanning etherchannel guard misconfig”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Which etherchannel protocol supports half duplex?

A

PAgP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Do portchannel commands overwrite individual port commands?

A

Not always. It’s best practice to keep configurations for the port channel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What must all ports in a layer 2 etherchannel agree on?

A

Speed, duplex, mapped VLANs, native VLAN, trunking protocol.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What must ports in a layer 3 etherchannel agree on?

A

No switch port, speed and duplex.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Refer to the exhibit. LACP has been configured on Switch1 as shown. Which is the correct command set to configure LACP on Switch2?

LACP_channel-group.jpg

A.
Switch2# configure terminal
Switch2(config)# interface range gigabitethernet3/1 -2
Switch2(config-if)# channel-group 5 mode auto

B.
Switch2# configure terminal
Switch2(config)# interface range gigabitethemet3/1 -2
Switch2(config-if)# channel-group 5 mode passive

C.
Switch2# configure terminal
Switch2(config)# interface range gigabitethernet3/1 -2
Switch2(config-if)# channel-group 5 mode desirable

D.
Switch2# configure terminal
Switch2(config)# interface range gigabitethernet3/1 -2
Switch2(config-if)# channel-group 5 mode on

A

Explanation

LACP trunking supports four modes of operation, as follows:
* On: The link aggregation is forced to be formed without any LACP negotiation. In other words, the switch will neither send the LACP packet nor process any incoming LACP packet. This is similar to the on state for PAgP.
* Off: The link aggregation will not be formed. We do not send or understand the LACP packet. This is similar to the off state for PAgP.
* Passive: The switch does not initiate the channel, but does understand incoming LACP packets. The peer (in active state) initiates negotiation (by sending out an LACP packet) which we receive and reply to, eventually forming the aggregation channel with the peer. This is similar to the auto mode in PAgP.
* Active: We are willing to form an aggregate link, and initiate the negotiation. The link aggregate will be formed if the other end is running in LACP active or passive mode. This is similar to the desirable mode of PAgP.

LACP does not have “auto” & “desirable” modes so A & C are not correct.

Also there are only three valid combinations to run the LACP link aggregate, as follows:

Switch Switch Description
active active Recommended
active passive Link aggregation occurs if negotiation is successful.
on on Link aggregation occurs without LACP. Although this works, it is not recommended.
Therefore if Switch1 is set “active” mode, we cannot set “on” mode on Switch2 -> D is not correct.

Only answer B is suitable in this case.

(Reference: http://www.cisco.com/en/US/tech/tk389/tk213/technologies_configuration_example09186a0080094470.shtml)

An example of configuring Layer 2 EtherChannel using LACP (applied these commands to both switches):

SW(config)#interface range f0/1 – 2
SW(config-if-range)#channel-group 1 mode active

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Refer to the exhibit. The command switchport mode access is issued on interface FastEthernet0/13 on switch CAT1. What will be the result?

channel-group_switchport-mode-access.jpg

A. The command will be rejected by the switch.
B. Interfaces FastEthernet0/13 and FastEthemet0/14 will no longer be bundled.
C. Dynamic Trunking Protocol will be turned off on interfaces FastEthernet0/13 and FastEthemet0/14.
D. Interfaces FastEthernet0/13 and FastEthernet0/14 will only allow traffic from the native VLAN.
E. Interfaces FastEthernet0/13 and FastEthernet0/14 will continue to pass traffic for VLANs 88,100,360.

A

Answer: B

Explanation

The default channel protocol in Cisco switches is Port Aggregation Protocol (PAgP). PAgP groups the interfaces with the same speed, duplex mode, native VLAN, VLAN range, and trunking status and type. After grouping the links into an EtherChannel, PAgP adds the group to the spanning tree as a single switch port.

An interface in the on mode that is added to a port channel is forced to have the same characteristics as the already existing on mode interfaces in the channel (applied for both PAgP & LACP). So if we configure “switchport mode access” on Fa0/13, this interface will no longer be bundled with Fa0/14.

(Reference: http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.1_14_ea1/configuration/guide/swethchl.html#wpxref12539)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the result of entering the command “port-channel load-balance src-dst-ip” on an EtherChannel link?

A. Packets are distributed across the ports in the channel based on both the source and destination MAC addresses.
B. Packets are distributed across the ports in the channel based on both the source and destination IP addresses.
C. Packets are balanced across the ports in the channel based first on the source MAC address, then on the destination MAC address, then on the IP address.
D. Packets are distributed across the access ports in the channel based first on the source IP address and then the destination IP addresses.

A

Answer: B

Explanation

The syntax of configuring load balancing on a Cisco switch is:

Switch(config)# port-channel load-balance method
Many methods can be used here. By default, the “src-dst-ip” (source and destination IP address) method is used for Layer 3 switching. Let’s take an example to understand more about this method.

EtherChannel_Load_balancing-src-dst-ip.jpg

In the topology above, Switch1 uses the “src-dst-ip” method to load balancing traffic to Switch2. With this method, only one link is used for a specific pair of source & destination IP address and the switch uses the XOR function to generate the hash that is used to determine which interface to use. Suppose the packets have the source IP of 1.1.1.1 & destination IP of 1.1.1.2. Write them in binary we get:

  1. 1.1.1 = 0000 0001.0000 0001.0000 0001.0000 0001
  2. 1.1.2 = 0000 0001.0000 0001.0000 0001.0000 0010

In this case we have only 2 interfaces in this channel group so the XOR function only gets the last bit, which means 1 XOR 0 = 1. Each interface is assigned an index that starts from 0 so Fa0/2 will be indexed 1 -> traffic will be sent over Fa0/2.

If we have 4 interfaces in a channel group then XOR function gets last 2 bits. If we have 8 interfaces, it gets 3 bits and so on. For example, with 8 interfaces the result will be 3 (because 001 XOR 010 = 011) -> Fa0/4 will be used.

Note: If the two address values have the same bit value, the XOR result is always 0. If the two address bits differ, the XOR result is always 1. For example, 0 XOR 0 = 0; 0 XOR 1 = 1; 1 XOR 0 = 1; 1 XOR 1 = 0.

In conclusion, the “port-channel load-balance src-dst-ip” command uses a pair of source & destination IP address to select the port to send traffic to -> B is correct.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Refer to the exhibit. Which statement is true about the display of the command “show pagp 1 neighbor” command?

show_pagp_neighbor.jpg

A. STP packets are sent out the Gi0/1 interface only.
B. STP packets are sent out both the Gi0/1 and Gi0/2 interfaces.
C. CDP packets are sent out the Gi0/1 interface only.
D. CDP packets are sent out the Gi0/2 interface only.

A

Answer: A

Explanation

DTP and CDP send and receive packets over all the physical interfaces in the EtherChannel while STP always chooses the first operational port in an EtherChannel bundle -> A is correct.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Refer to the exhibit. On the basis of the information that is generated by the show commands, which two EtherChannel statements are true? (Choose two)

show_etherchannel_summary.jpg

A. Interfaces FastEthernet 0/1 and 0/2 have been configured with the channel-group 1 mode desirable command.
B. Interfaces FastEthernet 0/3 and 0/4 have been configured with the no switchport command.
C. Interface Port-Channels 1 and 2 have been assigned IP addresses with the ip address commands.
D. Port-Channels 1 and 2 are providing two 400 Mbps EtherChannels.
E. Port-Channels 1 and 2 are capable of combining up to 8 FastEthernet ports to provide full-duplex bandwidth of up to 16 Gbps between a switch and another switch or host.
F. Switch SW1 has been configured with a Layer 3 EtherChannel.

A

Answer: A D

Explanation

In fact answer A is not totally correct because two ports Fa0/1 & Fa0/2 of Sw1 can use the “channel-group 1 mode auto” command while the peer ports use the “channel-group 1 mode desirable” command. But maybe it is the best choice in this case.

Answer B is not correct because this is a Layer 2 EtherChannel (from the lines “Po1 (SU)” & “Group state = L2″) but the “no switchport” is only used to configure Layer 3 EtherChannel.

Answer C is not correct because the port-channel is automatically created in a Layer 2 EtherChannel.

In this case we can see the ports are FastEthernet ports -> Port-Channels 1 and 2 are capable of combining up to 8 FastEthernet ports to provide full-duplex bandwidth of up to 1.6 Gbps (8 links of FastEthernet ports), not 16 Gbps. Port-Channels can provide up to 16 Gbps if they group 8 links of GigabitEthernet -> E is not correct.

SW1 has been configured with a Layer 2 EtherChannel (from the lines “Po1 (SU)” & “Group state = L2″) -> F is not correct.

Usually the EtherChannel protocol is shown when using the “show etherchannel summary” command (after the “Port-channel” column) but in this case we see no “protocol” column so we can assume it uses the default EtherChannel protocol PAgP.

There are 2 ports in each group so there are 4 Ethernet ports in total -> 4 x 100Mbps = 400Mbps in full duplex (which means “two 400 Mbps EtherChannels” in answer D) -> D is correct.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Which statement is true regarding the Port Aggregation Protocol?

A. Configuration changes made on the port-channel interface apply to all physical ports assigned to the portchannel interface.
B. Configuration changes made on a physical port that is a member of a port-channel interface apply to the port-channel interface.
C. Configuration changes are not permitted with Port Aggregation Protocol; instead, the standardized Link Aggregation Control Protocol should be used if configuration changes are required.
D. The physical port must first be disassociated from the port-channel interface before any configuration changes can be made.

A

Answer: A

Explanation

The port-channel interface represents for the whole bundle and all the configurations on this interface are applied to all physical ports that are assigned to this logical interface.

Note: We must manually create port-channel logical interface when configuring Layer 3 EtherChannels. The port-channel logical interface is automatically created when configuring Layer 2 EtherChannels (you can’t put Layer 2 ports into a manually created port channel interface).

An example of configuring Layer 3 EtherChannels with port-channel interfaces:

EtherChannel_Load_balancing-src-dst-ip.jpg

Switch1(config)# interface port-channel 1
Switch1(config-if)# no switchport
Switch1(config-if)# ip address 192.168.1.1 255.255.255.0
Switch1(config-if)# exit
Switch1(config)# interface range fastethernet0/1 -2
Switch1(config-if-range)# no switchport
Switch1(config-if-range)# no ip address
Switch1(config-if-range)# channel-group 1 mode desirable Switch2(config)# interface port-channel 1
Switch2(config-if)# no switchport
Switch2(config-if)# ip address 192.168.1.2 255.255.255.0
Switch2(config-if)# exit
Switch2(config)# interface range fastethernet0/1 -2
Switch2(config-if-range)# no switchport
Switch2(config-if-range)# no ip address
Switch2(config-if-range)# channel-group 1 mode auto
Note: The “no switchport” command is required to change interface from layer2 to layer3 mode.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Which three statements are true of the Link Aggregation Control Protocol (LACP)? (Choose three)

A. LACP is used to connect to non-Cisco devices.
B. LACP packets are sent with the command channel-group 1 mode desirable.
C. LACP packets are sent with the command channel-group 1 mode active.
D. Standby interfaces should be configured with a higher priority.
E. Standby interfaces should be configured with a lower priority.

A

Answer: A C D

Explanation

LACP is part of the IEEE specification 802.3ad so that it can be used on non-Cisco devices -> A is correct.

With mode “active”, the switch will send LACP packets, initiates negotiations with remote ports and willing to form a port-channel if it receives a response -> C is correct.

LACP uses the port priority with the port number to form the port identifier. The port priority determines which ports should be put in standby mode when there is a hardware limitation that prevents all compatible ports from aggregating.

An example of configuring LACP port priority:

Router(config-if)# lacp port-priority 100
Note: Valid range is from 1 to 65535. The higher the number, the lower the priority so standby interfaces should be configured with a higher priority -> D is correct.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Refer to the exhibit. What does the command channel-group 1 mode desirable do?

Interface FastEthernet 0/13
Channel-group 1 mode desirable
A. enables LACP unconditionally
B. enables PAgP only if a PAgP device is detected
C. enables PAgP unconditionally
D. enables Etherchannel only
E. enables LACP only if a LACP device is detected

A

Answer: C

Explanation

First, “desirable” is a mode on PAgP, not LACP. “enable PAgP unconditionally” means that port will send PAgP packets to form an EtherChannel port (initiate negotiations with other ports). A channel is formed with another port group in either desirable or auto mode.

Note:

Mode “auto” enables PAgP only if a PAgP device is detected and mode “on” forces the port to form a channel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Which statement best describes implementing a Layer 3 EtherChannel?

A. EtherChannel is a Layer 2 and not a Layer 3 feature.
B. Implementation requires switchport mode trunk and matching parameters between switches.
C. Implementation requires disabling switchport mode.
D. A Layer 3 address is assigned to the channel-group interface.

A

Answer: C

Explanation

By default, the ports on a multilayer switch (MLS) will all be running in Layer 2 mode. A port must be configured as a routing port before it is configured as a Layer 3 EtherChannel -> require to use the “no switchport” command.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What are 2 types of Etherchannel?

A
  • PAgP (Cisco Proprietary)
  • LACP (IEEE Standard)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What must match between interfaces to form etherchannel?

A
  • Duplex has to be the same.
  • Speed has to be there same.
  • Same native AND allowed VLANs.
  • Same switchport mode (access or trunk).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How do you configure PAgP etherchannel?

A

interface port-channel 10

switchport mode trunk

interface fastehternet 0/10 [11]

channel-group 10 mode [Auto/Desirable]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

How do you configure LACP etherchannel?

A

interface port-channel 10

switchport mode trunk

interface fastehternet 0/10 [11]

channel-group 10 mode [active/passive]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

How many interface can be in a port channel?

A

8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Why do you always assign an even number of interfaces in a port channel?

A

Because a Port channel can not properly load balance with an odd number of links.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

After an EtherChannel is configured between two Cisco switches, interface port channel 1 is in the down/down state. Switch A is configured with “channel-group 1 mode active”, while Switch B is configured with “channel-group 1 mode desirable”. Why is the EtherChannel bundle not working?

A

The switches are using mismatched EtherChannel negotiation modes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Which statement about the use of PAgP link aggregation on a Cisco switch that is running Cisco IOS Software is true?

A

PAgP modes are off, auto, desirable, and on. Only the combinations auto-desirable, desirable- desirable, and on-on allow the formation of a channel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Which EtherChannel negotiation protocol is configured on the interface f0/13 – f0/15?

A

Port Aggregation Protocol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

A network engineer changed the port speed and duplex setting of an existing EtherChannel bundle that uses the PAgP protocol. Which statement describes what happens to all ports in the bundle?

A

PAgP changes the port speed and duplex for all ports in the bundle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Which statement about using EtherChannel on Cisco IOS switches is true?

A

A switch can support up to eight compatibly configured Ethernet interfaces in an EtherChannel. The EtherChannel provides full-duplex bandwidth up to 800 Mbps only for Fast EtherChannel or 8 Gbps only for Gigabit EtherChannel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

A network engineer configured an Ethernet switch using these commands.

!

Switch1(config) # spanning-tree portfast bpdufilter default

!

Which statement about the spanning-tree portfast feature on the switch is true?

A

If an interface is enabled for portfast receives BDPU, the port goes through the spanning-tree listening, learning, and forwarding states

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

An EtherChannel bundle has been established between a Cisco switch and a corporate web server. The network administrator noticed that only one of the EtherChannel links is being utilized to reach the web server. What should be done on the Cisco switch to allow for better EtherChannel utilization to the corporate web server?

A

Adjust the EtherChannel load-balancing method based on source IP addresses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

An access switch has been configured with an EtherChannel port. After configuring SPAN to monitor this port, the network administrator notices that not all traffic is being replicated to the management server. What is a cause for this issue?

A

The port channel can be used as a SPAN source, but not a destination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What is the result of the configuration?

A

The EtherChannels would form and function properly even though the load-balancing and EtherChannel modes do not match.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

A network engineer tries to configure storm control on an EtherChannel bundle. What is the result of the configuration?

A

The settings will be applied to the EtherChannel bundle and all associated physical interfaces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

A network engineer must set the load balance method on an existing port channel. Which action must be done to apply a new load balancing method?

A

Configure the new load balancing method using port-channel load-balance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

A network engineer configured a fault-tolerance link on Gigabit Ethernet links G0/1, G0/2, G0/3, and G0/4 between two switches using Ethernet port-channel. Which action allows interface G0/1 to always actively forward traffic in the port-channel?

A

Configure LACP port-priority on G0/1 to 1.

64
Q

Which statement about switch S1 is true?

A

Physical port Fa0/13, Fa0/14, and Fa0/15 successfully formed a Layer 2 port-channel interface using an open standard protocol

65
Q

Users of PC-1 experience slow connection when a webpage is requested from the server. To increase bandwidth, the network engineer configured an EtherChannel on interfaces Fa1/0 and Fa0/1 of the server farm switch, as shown here:

Server_Switch#sh etherchannel load-balance
EtherChannel Load-Balancing Operational State (src-mac):
Non-IP: Source MAC address
IPv4: Source MAC address
IPv6: Source IP address
Server_Switch#

However, traffic is still slow. Which action can the engineer take to resolve this issue?

A

Change the load-balance method to dst-mac

67
Q

What is the maximum number of 10 Gigabit Ethernet connections that can be utilized in an EtherChannel for the virtual switch link?

A

8

68
Q

Which statement about restrictions for multichassis LACP is true?

A

Converting a port channel to mLACP can cause a service disruption.

69
Q

Define LACP

A

Defined in IEEE 802.1AD, defines a messaging protocol used to negotiate the dynamic creation of PortChannels (EtherChannels) and to choose which ports can be placed into an EtherChannel.

70
Q

Define PAgp

A

A Cisco-proprietary messaging protocol used to negotiate the dynamic creation of PortChannels (EtherChannels) and to choose which ports can be placed into an EtherChannel.

71
Q

How many links can be used in an EtherChannel?

A

2-8 FE, GE, or 10GE are bundled.

72
Q

What types of link can an etherchannel be?

A

access or trunk

73
Q

What are the restrictions for bundling into an Etherchannel?

A

must be same type, speed, VLAN(s), native vlan, pass the same set of vlans,duplex, and spanning tree settings

74
Q

How are frames forwarded across a specific link?

A

hashing algorithm

75
Q

What can the Etherchannel hash use?

A

source IP, dest IP, combination of source and dest IP, source and dest MAC, or TCP/UDP port numbers

76
Q

What are the port channel load balancing methods?

A

src-ip, dst-ip, src-dst-ip, src-mac, dst-mac, src-dst-mac, src-port, dst-port, src-dst-port

77
Q

What is the default mode of load balancing?

A

src-dst-ip

78
Q

What are the two etherchannel negotiation protocols?

A

PAgP (Cisco proprietary) and LACP (standards-based)

79
Q

What are the PAgP negotiation modes

A

on (all ports channel), auto (channels when asked), and desirable(actively asks to form a channel)

80
Q

How does PAgP form etherchannels?

A

only on ports that have same static VLANs or trunking. It also modifies parameters of the channel if one of the ports is modified

81
Q

What is a LACP priority?

A

the priority is a 2 byte value followed by the MAC that decides which ports are actively participating in Etherchannel (lower=higher priority)

82
Q

How many potential links can LACP define?

A

16, of which up to 8 are active. The others are in standby

83
Q

what is the range of PAgP channel group numbers?

A

1 to 64

84
Q

By default, what submode does PAgP operate in with the desirable and auto modes?

A

silent

85
Q

what should you do if you expect a PAgP capable switch at the other end vs. a server or host?

A

configure non-silent submode

86
Q

What are the steps to configure a PAgP port channel?

A

1-(opt) configure load balancing, 2-select the interface(s), 3-assign the protocol, 4-select the mode and submode

87
Q

What is the LACP priority range?

A

1-65535 (def 32768) lower priority, higher probability

88
Q

How do you configure LACP standby links?

A

LACP port priority

89
Q

What are the steps to configure a LACP port channel?

A

1-(opt) set system priority, 2-select interface(s), 3-assign the protocol, 4-set the mode, 5-(opt) set the port priority

90
Q

If one end of an Etherchannel (either type) is set to on and the channel doesn’t form, what should you check?

A

Both ends should be on because on modes doesn’t send PAgP or LACP packets

91
Q

What must the other end be set to if PAgP desirable or LACP active mode is selected?

A

either desirable or auto mode

92
Q

Can two switches in the auto(PAgP) or passive (LACP) mode create a channel? Why?

A

no because they only participate if asked

93
Q

What are the only modes for PAgP and LACP that with exchange negotiation packets?

A

Active/Desirable, and Passive/Auto.

94
Q

What method is the default for load balancing on Layer 2 with EtherChannel?

A

source MAC, or src-mac

95
Q

What are the three operating modes for LACP?

A

-On, does not negotiate-Active, actively seeks to form a channel-Passive, negotiates only if far end initiates it.

96
Q

When in non-trunk, all bundled ports must be on the same ______ to be in the same EtherChannel?

A

VLAN

97
Q

What are the possible commands that can be added to ‘show etherchannel’ ?

A

summary, port, port-channel, detail, load-balance.

98
Q

What is the command to change the LACP system priority value?

A

(Config)lacp system-priority #####

99
Q

How many potential links does LACP allow for in a EtherChannel?

A

It allows for 16, but only 8 are used at a time, chosen by their port priority value (lowest wins!)

100
Q

What configuration step will turn a Layer 2 EtherChannel into a Layer 3 EtherChannel?

A

Adding and IP address to the PortChannel interface.

101
Q

What method is the default for load balancing on Layer 3 with EtherChannel?

A

source and destination IP, or ‘src-dst-ip’

102
Q

On PAgP links, when should the non-silent command be added to the end of the ‘channel-group’ command?

A

When you expect another PAgP-capable switch to be on the other end. This allows for more accurate information for the Spanning Tree Protocol.

103
Q

If two ports are in the Passive/Auto mode for LACP and PAgP, will they establish a connection?

A

No! they both wait for the other side to initiate!

104
Q

All ports bundled in EtherChannel should have identical settings for what?

A

Speed, Duplex, and Spanning-Tree.

105
Q

What is the command to change the LACP port priority value?

A

(if)lacp port-priority #####

106
Q

What does PAgP do if a configuration is made on a single port in the EtherChannel?

A

It reconfigures all of the other ports to match the change.

107
Q

What does IEEE 802.3ad define?

A

LACP (Link Aggregation Control Protocol)

108
Q

What is the value range and default value of the LACP system-priority and port-priority?

A

1-65536, and the default is 32768.

109
Q

What are the two methods of negotiating bundled links in Cisco Switches?

A

PAgP (Port Aggregation Protocol, Cisco proprietary) and LACP (Link Aggregation Control Protocol, Standards based).

110
Q

What happens when two switches connected via EtherChannel and LACP have different LACP system priority values? the same values?

A

-If different, the system with the lowest value will make all decisions about the EtherChannel makeup.-If the same, the switch with the lowest MAC address will make the decisions about the EtherChannel.

111
Q

The load balancing hashing algorithm can use what factors to load balance?

A

source IP, Destination IP, a combination of source/dest IP, source/dest MAC, or TCP/UDP port numbers.

112
Q

What must happen on all ports to be bundled into the same trunk on an EtherChannel group?

A

They must be in trunking mode, have the same native VLAN, and pass the same VLANs.

113
Q

What logical operation is used by the hashing algorithm on the frame bits to decide on a link for load balancing?

A

XOR

114
Q

What are the three operating modes for PAgP?

A

-On, does not negotiate-Desirable(Active!) actively seeks to form a channel-Auto(Passive!), the default, negotiates only if far end initiates it.

115
Q

In EtherChannel frames are balanced on the links according to ________?

A

A hashing algorithm that can use; source IP, Destination IP, a combination of source/dest IP, source/dest MAC, or TCP/UDP port numbers.

116
Q

What two commands must be placed on a switch port before it can become part of a EtherChannel group?

A

(if)channel-protocol [PAgP/LACP]channel-group # mode [on/auto/desirable]

117
Q

If more than 8 ports are added to an LACP EtherChannel, what happens with the ports with high port-priority numbers?

A

Lower port-priorities are made active ports in the group, and higher ones are placed into the standby status.

118
Q

What are the 9 possible methods that can be used with the ‘#port-channel load-balance’ command?

A

scr-ip, dst-ip, src-dst-ip, src-mac, dst-mac, src-dst-mac, src-port, dst-port, src-dst-port.

119
Q

How many links can be in a single EtherChannel?

A

2-8 links of FastEther, GigEther, or 10GEther.

120
Q

what is errdisable pagp-flap?

A

etherchannel ports have inconsistent config

121
Q

if the switchport is part of an etherchannel, where is the network assigned

A

to the virtual port-channel interface

122
Q

What happens in a traffic loading situation for EtherChannel when two servers pass files between each other?

A

All of the traffic between the servers crosses the same segment. This happens because the servers use the same MAC address for all of the frames. The ECB performs an X-OR on the MAC addresses and comes up with the same result every time.

123
Q

If you have access to equipment, attempt to configure a two-segment EtherChannel where one end is set to transport only VLANs 1–10 and the other end of the segment is set to transport all VLANs. What gets established?

A

Nothing. Both ends of an EtherChannel must be configured to pass the same set of VLANs on all interfaces.

124
Q

Default etherchannel load balancing method

A

Source MAC

125
Q

What does *PAgP* stand for?

A

Port Aggregation Protocol

126
Q

What does *LACP* stand for?

A

Link Aggregation Control Protocol

127
Q

What is *PAgP*?

A

PAgP is a Cisco proprietary link aggregator protocol that can bundle up to 8 active ports.

128
Q

What is *LACP*?

A

LACP is an Internet Standard protocol and bundles up to 8 active ports, but allows additional ports on standby.

129
Q

How is *LACP Master* determined?

A

LACP Master is determined the same way as STP with system priorities and port priorities. The default priority is 32768 and lower number is better.

130
Q

Which link aggregation protocol works in half-duplex?

A

PAgP works in half-duplex.

131
Q

Which link aggregation protocol works in full-duplex?

A

LACP works in full-duplex

132
Q

What is a *Manual EtherChannel*?

A

A Manual EtherChannel, unlike PAgP or LACP, does not send any control packets to bring up bundled links.

133
Q

What configuration commands sets up a bundled link?

A

Switch(config-if)# channel-group <#> mode {mode-type}

134
Q

What are the modes of *PAgP*?

A

PAgP has two modes, auto and desirable. Similar to DTP, auto accepts bundle requests while desirable actively attempts to convert the link into an EtherChannel bundle.

135
Q

What are the modes of *LACP*?

A

LACP has two modes, passive and active. Active attempts to convert the link into a bundled EtherChannel, while Passive waits for control packets before agreeing to a bundle request. Basically, same as auto and desirable in PAgP.

136
Q

What is the main benefit of using a Layer 3 EtherChannel compared to Layer 2?

A

The main benefit of Layer 3 is that there is no issue with sharing a broadcast domain or STP convergence delays.

137
Q

What is the main benefit of EtherChannels in general?

A

The main benefit of EtherChannel is redundancy.

138
Q

How is data load balanced in EtherChannel?

A

EtherChannel load balances on a per-flow basis round-robin style by default.

139
Q

Why is EtherChannel not a true bandwidth increase?

A

EtherChannel is not a true bandwidth increase because each flow in dedicated to a single port in the bundle. This means if one flow exceeds that port’s bandwidth, there will be drops.

140
Q

What is the recommended number of ports to have in an EtherChannel?

A

The recommended number of ports to have in an EtherChannel is 2, 4, or 8 in order to hash equally.

141
Q

What configuration command changes the load balancing hash algorithm for EtherChannel?

A

Switch(config)# port-channel load-balance {src-mac | dst-mac | src-dst-mac …}

142
Q

What is a helpful show command that can display information about an EtherChannel load balancing algorithm?

A

Switch# show etherchannel load-balance

143
Q

What is *EtherChannel Misconfiguration Guard*?

A

An EtherChannel Misconfiguration Guard is a mechanism to detect incorrect configurations in a port-channel setup. This is done based on the fact that all ports in a bundle should share the same MAC address, so if a port’s BPDU reports a different MAC address, then that suggests an incorrect configuration to the remote-end.

144
Q

What configuration command sets *EtherChannel Misconfiguration Guard*?

A

Switch(config)# spanning-tree etherchannel guard misconfig

myCCNP Switch 300-115 (73 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions