VLAN Trunks and EtherChannel Bundles Flashcards
What are four roles in the VTP architecture?
Server,
Client,
Transparent,
off.
Explain Server role in VTP!
The server switch is responsible for the creation, modification, and deletion of VLANs within the VTP domain.
Explain Client role in VTP!
The client switch receives VTP advertisements and modifies the VLANs on that switch.
Can VTP Client create VLAN’s?
VLANs cannot be configured locally on a VTP client.
Explain Transparent role in VTP!
VTP transparent switches receive and forward VTP advertisements but do not modify the local VLAN database. VLANs are configured only locally.
Explain Off role in VTP!
: A switch does not participate in VTP advertisements and does not forward them out of any ports either. VLANs are configured only locally.
VTP Versions 1 and 2 limited propagation to VLANs numbered …
1 - 1005
VTP Version 3 allows range of VLANs …
1 - 4094
VTP domain is Version 3, the primary VTP server must be set with the executive command
vtp primary
What are three main types of advertisements:
Summary,
Subset,
Client requests
What Summary advertisement in VTP contains and when it occurs?
This advertisement occurs every 300 seconds or when a VLAN is added, removed, or changed.
It includes the VTP version, domain, configuration revision number, and time stamp.
Subset advertisement in VTP?
This advertisement occurs after a VLAN configuration change occurs.
Client requests advertisement inv VTP?
This advertisement is a request by a client to receive more detailed subset advertisement. Typically, this occurs when a switch with a lower revision number joins the VTP domain
Steps for configuring VTP?
SW1(config)# vtp domain CiscoPress SW1(config)# vtp version 3 SW1(config)# vtp mode server Setting device to VTP Server mode for VLANS. SW1(config)# vtp password PASSWORD Setting device VTP password to PASSWORD
Show VTP revision number
show vtp status
It is very important that every switch that connects to a VTP domain has the VTP revision number reset to …
0 (zero)
There are three modes to use in setting a switch port to trunk?
Trunk (switchport mode trunk)
Dynamic desirable, (switchport mode dynamic desirable )
Dynamic auto. (switchport mode dynamic auto)
If both ends of a link are configured as dynamic auto, is trunk going to be established?
No, switchport mode dynamic auto does not advertises DTP packets.
Verify trunk port status on interface g1/0/1.
show interface g1/0/1 trunk
Show all trunk interfaces on a switch?
show interfaces trunk
What Interface command prevents that port from forming a trunk port with a dynamic desirable or dynamic auto?
switchport nonegotiate
Physical interfaces that are used to assemble the logical EtherChannel are called …
member interfaces
EtherChannels can be used for either Layer 2 (access or trunk) or Layer 3 (routed) forwarding? True or False?
True
Two common link aggregation protocols are …
Link Aggregation Control Protocol (LACP)
and
Port Aggregation Protocol (PAgP is Cisco proprietary)
PAgP advertises messages with the multicast MAC address __________
and the protocol code __________
0100:0CCC:CCCC
0x0104
What are PAgP Port Modes?
Auto and Desirable
How PAgP Auto mode works?
Interface does not initiate an EtherChannel to be established and does not transmit PAgP packets out of it.
If both devices are PAgP auto, a PAgP adjacency does not form.
How PAgP Desirable mode works?
Desirable: In this PAgP mode, an interface tries to establish an EtherChannel and transmit PAgP packets out of it.
Active PAgP interfaces can establish a PAgP adjacency only if the remote interface is configured to auto or desirable.
What are 2 LACP Port Modes?`
Active and Passive
How LACP Passive port mode works?
Interface does not initiate an EtherChannel to be established and does not transmit LACP packets out of it.
If an LACP packet is received from the remote switch, this interface responds and then can establish an LACP adjacency.
If both devices are LACP passive, does LACP adjacency form?
If both devices are LACP passive, an LACP adjacency does not form.
How active LACP mode works?
Interface tries to establish an EtherChannel and transmit LACP packets out of it.
Active LACP interfaces can establish an LACP adjacency only if the remote interface is configured to active or passive
What is configuration command for configuring static EtherChannel?
channel-group etherchannel-id mode on.
What is command for configuring LACP EtherChannel?
channel-group etherchannel-id mode {active | passive}
What is command for configuring PAgP EtherChannel?
channel-group etherchannel-id mode {auto | desirable} [non-silent]
PAgP ports operate in silent mode, which allows a port to establish an EtherChannel with a device that is not PAgP capable
What keyword requires a port to receive PAgP packets before adding it to the EtherChannel?
non-silent
channel-group etherchannel-id mode {auto | desirable} [non-silent]
What are additional factors that need to be considered with EtherChannel configuration?
- Configuration settings for the EtherChannel are placed in the port-channel interface.
- Member interfaces need to be in the appropriate Layer 2 or Layer 3 (that is, no switch port) before being associated with the port channel. The member interface type dictates whether the EtherChannel operates at Layer 2 or Layer 3.
Simple LACP Port-Channel Configuration commands?
SW1# configure terminal
SW1(config)# interface range gi1/0/1-2
SW1(config-if-range)# channel-group 1 mode active
SW1(config-if-range)# interface port-channel 1
SW1(config-if)# switchport mode trunk
SW2# configure terminal
SW2(config)# interface range gi1/0/1-2
SW2(config-if-range)# channel-group 1 mode passive
SW2(config-if-range)# interface port-channel 1
SW2(config-if)# switchport mode trunk
Verify with show command that the port channel has been established!
show etherchannel summary
Display additional information about the LACP neighbor!
show lacp neigh
What can LACP system identifier verify?
It is used to verify that the member interfaces are connected to the same device and not split between devices.
Display additional information about the PAgP neighbor?
show pagp neighbor
Display LACP counters
show lacp counters
Clear lacp counters.
clear lacp counters
The original LACP standards sent out LACP packets every how many seconds?
30 seconds
A link is deemed unusable if an LACP packet is not received after …
3 intervals. Which results in a potential 90 seconds of packet loss for a link before that member interface is removed from a port channel.
LACP fast packets are advertised how often.
every 1 second. a link can be identified and removed in 3 seconds.
Enable LACP fast on the member interfaces with the interface configuration command?
SW1(config)# interface range gi1/0/1-2
SW1(config-if-range)# lacp rate fast
All the interfaces on both switches need to be configured the same—either using LACP fast or LACP slow—for the EtherChannel to successfully come up
Display how interface is configured, fast or slow LACP?
show lacp internal
Configure the minimum number of EtherChannel member interfaces?
interface port-channel 1
port-channel min-links 2
Portchannel is not up, what is the problem?
SW1# show etherchannel summary
! Output Ommitted for Brevity
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator
M - not in use, minimum links not met
..
Group Port-channel Protocol Ports
——+————-+———–+———————————————–
1 Po1(SM) LACP Gi1/0/1(D) Gi1/0/2(P)
M - not in use, minimum links not met
Configure the minimum number of EtherChannel member interfaces?
SW1(config)# interface port-channel1
SW1(config-if)# lacp max-bundle 1
(2, 4, 8)
The port-channel master switch controls which member interfaces (and associated links) are active by examining the LACP port priority. How?
A lower port priority is preferred. If the port priority is the same, then the lower interface number is preferred.
Configuration commmand for changing LACP system priority.
lacp system-priority priority
Display LACP system priority
SW1# show lacp sys-id
What is LACP System Priority used for?
The LACP system priority identifies which switch is the master switch for a port channel.
The master switch on a port channel is responsible for choosing which member interfaces are active in a port-channel when there are more member interfaces than the maximum number of member interfaces associated with a port-channel interface.
What is LACP Interface Priority used for?
LACP interface priority enables the master switch to choose which member interfaces are active in a port channel when there are more member interfaces than the maximum number of member interfaces for a port channel.
Which LACP interface priority is preferred, lower or higher?
lower
What is the Interface configuration command that sets LACP interface priority
SW1(config)# interface gi1/0/2
SW1(config-if)# lacp port-priority 1
What configuration settings must match on the member interfaces?
Port type:
Every port in the interface must be consistently configured to be a Layer 2 switch port or a Layer 3 routed port.
Port mode:
All Layer 2 port channels must be configured as either access ports or trunk ports. They cannot be mixed.
Native VLAN:
The member interfaces on a Layer 2 trunk port channel must be configured with the same native VLAN, using the command switchport trunk native vlan vlan-id.
Allowed VLAN:
The member interfaces on a Layer 2 trunk port channel must be configured to support the same VLANs, using the command switchport trunk allowed vlan-ids.
Speed:
All member interfaces must be the same speed.
Duplex:
The duplex must be the same for all member interfaces.
Check the following when troubleshooting the establishment of an EtherChannel bundle:
Ensure that a member link is between only two devices.
Ensure that the member ports are all active.
Ensure that both end links are statically set to on and that either LACP is enabled with at least one side set to active or PAgP is enabled with at least one side set to desirable.
Ensure that all member interface ports are consistently configured (except for LACP port priority).
Verify the LACP or PAgP packet transmission and receipt on both devices.
load-balancing hash is a systemwide configuration that uses the global command port-channel load-balance hash.
- dst-ip: Destination IP address
- dst-mac: Destination MAC address
- dst-mixed-ip-port: Destination IP address and destination TCP/UDP port
- dst-port: Destination TCP/UDP port
- src-dst-ip: Source and destination IP addresses
- src-dest-ip-only: Source and destination IP addresses only
- src-dst-mac: Source and destination MAC addresses
- src-dst-mixed-ip-port: Source and destination IP addresses and source and destination TCP/UDP ports
- src-dst-port: Source and destination TCP/UDP ports only
- src-ip: Source IP address
- src-mac: Source MAC address
- src-mixed-ip-port: Source IP address and source TCP/UDP port
- src-port: Source TCP/UDP port
What is the global configuration command for configuring load-balancing hash?
port-channel load-balance hash
