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Switching Flashcards by Michael Shultz

What are the three layers of the Hierarchical Model? What are the major functions and requirements of each?

• Core - transmitting traffic at high
speeds. Low overhead and high
bandwidth are necessary.

• Distribution - aggregates access 
  nodes and uplinks. Implementation 
  of policies like filtering, security 
  and QoS. High availability through 
  redundancy and appropriate 
  software.

• Access - provides access and
aggregation for users. Feature-rich.

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Stackable switching

Having multiple switches that appear and act as a single switch.

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What is meant by the consumerization of network access?

The fact that consumer devices (smart phones, tablets) are increasingly used for business purposes and need to be accommodated by business networks.

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PPDIOO

Prepare
Plan
Design
Implement
Operate
Optimize

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What information does the show VLAN command provide?

All valid VLANs, their names, their statuses and which ports belong to them.

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What is 802.1q?

A trunking encapsulation mechanism that adds VLAN tags to frames traveling over a trunk.

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What is another term for a trunk?

Inter-switch link

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The only trunking negotiation scenario that ends up negotiating (or defaulting to) an access link is:

Both ports set to “auto”

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The only trunking negotiation scenario that results in limited connectivity is:

One port set to “trunk” and the other set to “access”.

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What is the command to set a trunk’s encapsulation method to 802.1q?

(config-if)# switchport trunk encapsulation dot1q

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What is the command to turn off trunking negotiation?

(config-if)# switchport trunk nonegotiate

only use this when manually configuring a trunk

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What does VTP stand for and what is its function?

VLAN Trunk Protocol (VTP) reduces administration in a switched network. When you configure a new VLAN on one VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere. VTP is a Cisco-proprietary protocol that is available on most of the Cisco Catalyst series products.

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Why is using VTP sometimes dangerous?

A VLAN configuration on a VTP server can overwrite existing configurations on switches. eg: if you had a VTP server with no configured VLANs, it will overwrite the configuration of all switches in the domain and delete any previously configured VLANs.

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What’s the command to designate a protected port?

(config-if)# switchport [no] protected

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How many community and isolated VLAN’s can you have per primary VLAN?

Multiple community VLANs but only one PVLAN

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Which ports are typically promiscuous?

Ones that lead to services that other devices need to share and ports that lead to a router or a firewall that controls access between PVLANs

What are the three options for configuring EtherChannel and the commands associated with each?

PAgP - desireable, auto

LACP - active, passive

Static configuration (no protocol) - on, off

Sw1# sh run int e0/1

Shows the running configuration of the port e0/1 - good for checking for configuration mismatches between ports.

What command will show you what port bundles you have configured and the status of each?

Switch# show etherchannel summary

In CST, what is the default cost of a 10 Mbps link?

100

In CST, what is the cost of a 10 Gbps link?

What is the command chain to change port cost in spanning tree?

(config)# interface fa0/1

(config-if)# spanning-tree vlan [#] cost [#]

What the command chain for manipulating port priority in spanning tree?

(config)# interface fa0/2
(config-if)# spanning-tree (*vlan [#]) port-priority [#]

*for use on trunk ports only

How do priority and cost affect the likelihood of a port being chosen as a designated port?

The higher the priority, the more likely it is to be a designated port. The higher the cost, the less likely it is to be a designated port.

In RSTP, what are the two new types of ports? What are they/what do they do?

Alternate - a failover port for a root port Backup - failover for a designated port If the root port or designated port goes down, the alternate or back up port will immediately going to forwarding mode. This obviates the need for the STA to run all over again, which could take an entire 50 seconds. Rapid spanning tree does, however, require more up-front calculation.

Command to enable BPDUGuard on all PortFast-enabled ports:

(config)# spanning-tree portfast bpduguard

What command will tell you which STP additions are enabled, and the total #'s of blocking, forwarding, STP active, etc, ports?

switch# show spanning-tree summary totals

What are the three layers of the SONA model?

* Integrated Applications Layer * Interactive Services Layer * Networked Infrastructure Layer

As an architectural framework, what does SONA guide the evolution of?

Enterprise networks to a more intelligent infrastructure.

Describe the Core layer in the Cisco Enterprise Campus Architecture:

A layer 3 network that interconnects the different buildings in a campus.

What are two network benefits provided by VLANs?

VLANs minimize the impact of network problems. They allow you to segregate frames that contain sensitive or critical information.

What is the function of rootguard?

Prevents a device from becoming to root bridge

What is the function of BPDUGuard?

It shuts off a PortFast-enabled port if a BPDU is received on it. PortFast should be enabled only on ports that can't result in a topological loop, like ports connected to end-point devices. BPDUGuard ensures that a switch (which could result in a loop) isn't connected to a port configured specifically for an end-point device (which can't result in a loop).

In an 802.1q frame, where is the vlan tag placed?

Between the source address field and the ethertype/length field.

What portion of a frame do switches use to populate their MAC tables?

The Source Address of a received frame. This is really The only way this could work because switch can't use a destination MAC address to populate its MAC table when it doesn't yet know the location of the device to which the destination MAC address belongs.

What are the two main switching methodologies and how does each work?

• store-and-forward - The switch waits until the entire frame has been received and then makes a forwarding decision. • cut-through - the switch theoretically begins forwarding after it receives the first 7 bits (the destination MAC address or DMAC). In reality, though, newer cut-through switches often wait for more data to arrive in order to make more sophisticated forwarding decisions.

Set S1's FastEthernet 0/1 interface to act as an access port. Configure port security so that it will only accept the MAC address abcd.ef12.3456 then save the running configuration.

``` S1>enable S1#conf t S1(config)#int fa0/1 S1(config-if)#switchport mode access S1(config-if)#switchport port-security S1(config-if)#switchport port-security maximum 1 S1(config-if)#switchport port-security mac-address abcd.ef12.3456 S1(config-if)#exit S1(config)#end S1#copy running-config startup-config ```

Set S1's VTP mode to server and the VTP domain name to VTPDomain. Configure VLAN 999 with IP address 172.16.1.1 /24 and name it "Management". Set the default gateway to 10.1.1.1. Create VLAN 10 and name it "Finance". Configure the FastEthernet 0/2 interface to act as a trunk port and assign it VLANs 999 and 10. Configure port security on fa 0/2 so that S1 will accept two MAC addresses and will store these addresses in its running configuration.

``` S1>enable S1#conf t S1(config)#vtp mode server S1(config)#vtp domain name VTPDomain S1(config)#vlan 999 S1(config-vlan)#name Management S1(config-vlan)#exit S1(config)#int vlan 999 S1(config-if)#ip address 172.16.1.1 255.255.255.0 S1(config-if)#exit S1(config)#ip default-gateway 10.1.1.1 S1(config)#vlan 10 S1(config-vlan)#name "Finance" S1(config-vlan)#exit S1(config)#int fa0/2 S1(config-if)#switchport mode trunk S1(config-if)#switchport trunk allowed vlan 999, 10 S1(config-if)#switchport port-security S1(config-if)#switchport port-security maximum 2 S1(config-if)#switchport port-security mac-address sticky ```