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Enterprise Final
| Question | Answer |
|---|---|
| ISL | Old Cisco Proprietary trunking protocol |
| 802.1q | New standard trunking protocol |
| Default VLAN, always exists | VLAN 1 |
| Untagged traffic on trunk | Native VLAN |
| Management VLAN | virtual network interface associated with VLAN |
| DTP | dynamic trunking protocol, turn off with sw nonegotiate |
| SVI | Switch virtual interface, configured for management |
| Benefits to using VLAN | cheap, reduce traffic, policy, navigability |
| Set port to always be trunk | sw mo tr |
| Set port to always be access | sw mo acc |
| Set port to actively try to be trunk | sw mo dyn des |
| Set port to passively be willing to become a trunk | sw mo dyn auto |
| What do you need to configure on a router to allow trunk port to route between VLANS? | sub-interface |
| Command to set sub interface to a vlan? | encaps dot1q 100 [native] |
| Do sub-interface require no shut command? | Nope, just the actual interface |
| Do routers use DTP? | nope, so you may as well 'sw nonegotiate' on the switch |
| If using port security on trunk port facing router, how many MAC address MAX to set? | 1 MAC for every sub interface, even if they don't have IP's set to the interfaces |
| Where is switch config data saved? | startup-config + flash:vlan.dat |
| Should you disable CDP on access ports? | Yes, they send out information that an access port has no use to know but can be a security risk. |
| Where should CDP be enabled? | Trunk ports, it gives valuable troubleshooting info. |
| Why did they even invent VTP, its so awful?! | Because people are lazy, and this was supposed to help! |
| Whats the big deal about this VTP thing anyways? | Well it has security risks, also with bad implementation it can take down a network. |
| Disadvantages of ISL? | 30 byte header, only 1000 VLANs supported, and only CISCO |
| Does VTP data travel over access links? | Nope! |
| Which VTP settings need to be the same for switches to accept the data? | Password, Domain, Version all must be the SAME |
| What happens if all the switches are set to VTP client mode? | Network may crash. Also cannot change any of the VLAN information. |
| Do VTP servers store vlan data in flash: vlan.dat? | Yup! |
| Do VTP clients store vlan data in flash: vlan.dat? | Nope! They only store it in the running config. This means you save space in NVRAM! |
| Do VTP transparent switches store vlan data in flash: vlan.dat? | Mmhmm! |
| VTP Pruning | dynamically remove VLANs allowed on a trunk to reduce broadcast traffic. |
| What VTP configuration revision will a switch accept information from? | It must be a higher revision number. |
| What is the revision number of a VTP transparent switch? | 0 |
| How can you reset the VTP revision number? | switch the VTP domain or set it to VTP mode transparent |
| How often are VTP summary messages sent? | 5 minutes or when creating / deleting / renaming a VLAN. |
| What should you do before you reset a switch back to VTP defaults? | disconnect the cabling, VTP defaults mean that it will accept other VTP info right away. |
| Should the DNS domain be different than the VTP domain? | Appearantly, maybe so people don't guess your VTP domain name to screw with it? Not sure... |
| Is the VTP domain name case sensitive? | iT sUrE iS! |
| Does vtp pruning update automatically? | Yes, even when there are NO configuration revision changes (lets say you only change cabling scheme) it will redo the pruning. |
| Flapping / Bad MAC address entries? | Layer 2 loop can cause the mac address to change between the ports which are part of the loop. |
| Broadcast storm? | Layer 2 loops, cause broadcast traffic to eventually consume all bandwidth of devices. |
| Duplicate Unicast frames? | Layer 2 loops, cause the same frame to reach the destination at different times. |
| STP Hello Timer! | 2 seconds |
| STP Max-Age Timer! | 20 seconds (10 x hello timer) |
| STP Forward Delay Timer! | 15 seconds |
| Convergence Time of spanning-tree? | 50 seconds |
| Convergence Time of rapid spanning-tree? | 6 seconds (3 x hello) |
| STP Link Cost of 10Gb link | 2 |
| STP Link Cost of 1Gb link | 4 |
| STP Link Cost of 100Mb link | 19 |
| STP Link Cost of 10Mb link | 100 |
| Legacy Port States? | Disabled, Blocking, Listening, Learning, Forwarding |
| Rapid-pvst Port States? | Discarding, Learning, Forwarding |
| Port Roles | Root, Designated, Blocking (rapid = Alt/Backup) |
| Spanning tree frame? | BPDU |
| Who becomes the Spanning-tree root anyhow? | LOWEST BID!! (Bridge ID) |
| How do you tell which ports are assigned Root, Designated or Blocked? | Add up the STP link values to get to the root, shortest gets the preference (Root or designated). |
| What is a standby IP? | Virtual IP that multiple routers will use. |
| What is the default priority for HSRP? | 100 |
| How much will the priority go down if a tracked interface fails in HSRP? | -10 |
| What command must be set on a router for it to resume priority in HSRP? | Preempt |
| How can there be duplicate unicast frames? | switch that doesn't have destination MAC for the frame will flood it out all other ports...if there is a loop WHOOPS! |
| What is STA? | NO, its not a wireless station (in this course), its the SPANNING TREE ALGORITHM! |
| Whats inside that BID anyhow? | Priority - Extended System ID (FOR VLANs!) - MAC address |
| What is the default priority for STP? | 32768 |
| What is the default priority for STP if its in VLAN 12? | 32768 + 12 = 32780 |
| What is the reference point that STA uses to figure out which paths to block? | THE ROOT BRIDGE! |
| Whats inside a BPDU? | ID of the root bridge and cost of the path to it, as well as timer settings |
| How are BPDUs sent? | encapsulated inside ethernet frame and sent to spanning-tree multicast address. |
| What is the priority range of STP? | 1 - 65536 |
| What happened to the STP priority value when they implemented Extended System ID? | Priority now multiples of 4096 |
| What could be a problem with using the STP priority primary command instead of setting a value? | primary command will set it to 24576 or lower than current root by 4096. It won't update itself if a lower priority switch comes online / added. |
| What are the ports roles set to on a Root Bridge? | All ports will be designated |
| What would happen if 2 ports on a switch have the same path cost to root bridge? | 1st - Port priority, 2nd - lower port ID. Fa0/1 would have priority over Fa0/24 |
| Default port priority? | 128 ( portID# is in some small way added to this number ) |
| On a segment with no root port which gets designated? | 1st - lowest path cost to root bridge, 2nd - BID is used in case of a path cost tie |
| PORT STATES – Blocking / Listening | not forwarding or learning mac but still listen to bpdu for changes. Listening is about to change to learning and experiences forward delay interval! |
| PORT STATES - Learning | not forwarding but is learning mac. Experiences forward delay interval. |
| PORT STATES - Forwarding | This is like a normal port! |
| PORT STATES - Disabled | This port is turned off! |
| Forward Delay Interval | When ports go through the temporary listening and learning states. Both states get full 15 seconds delay times. |
| Max network diameter? | 7 is default max, delay times allow for convergence. |
| Portfast? | Skip that delay time! Allows PCs to use DHCP properly. |
| PVST info! | CISCO, Pre-VLAN spanning tree protocol. OLD! |
| PVST+ | CISCO! = Now with VLANs! |
| Rapid-PVST+ | CISCO = Now even faster! |
| RSTP | IEEE = Also Rapid! |
| MSTP | IEEE = Multiple Vlan can be mapped to same spanning-tree instance!(huh?) |
| Advantage of VLAN Spanning Tree Support | with VLAN support you can have different Roots for different VLANs! Share the load. |
| Disadvantage of VLAN Spanning Tree Support | with VLAN support comes more BPDUs to handle the different VLANs. |
| CISCO 2960 STP DEFAULTS! | PVST+, priority = 32768, port priority = 128, STP Costs = 10G/2, 1G/4, 100M/19, 10M/100, Timers: Hello = 2, Forward Delay = 15, Max Age = 20 |
| 802.1D | Old spanning tree standard. 50 second converge time. |
| 802.1w | RSTP! Rapid so 6 second converge time (3 hellos) compared to old 50 standard. |
| Edge Port | not intended to be connected to another switch, immediate forwarding state. |
| How to increment VTP revision #? | add / delete a VLAN, add / change a VLAN name. |
| Default existing VLANs on a switch? | 5 = (1, 1002-1005) |
| VTP Subset Advertisements | actual content of the changes that occurred |
| VTP Request Advertisements | Request VTP info, occurs when: domain name changed, summary received with a higher revision #, subset advertisement missed, switch reset |
| Which ports get prunned by VTP Pruning? | The egress port of a switch where the VLAN should not flow past. Ex: (10,20) - S1 X - S2 (20) X= Point where VLAN is pruned. |
| Can broadcast messages travel between VLANs? | No, VLANs are separate broadcast domain, need routing to communicate with each other. Broadcast messages do not travel through a router. |
| Should VLANs be on different subnets? | If you want them to work with routing, it might be a good idea. |
| Can you use access ports to communicate with a router to cross VLANs? | Yes, but it uses 1 port on the router for every VLAN you have. |
| How can 1 port on a router communicate between many VLANs? | Sub-interfaces on the port and the link will be a trunk. |
| What are the advantages to using Router-on-a-stick? | Less interfaces used, save money, reduce cabling complexity, allows for better scaling. |
| What are the disadvantages to using Router-on-a-stick? | Creates a bottleneck, increases the configuration complexity. |
| If having problems with a Router on a stick, what might be a likely cause? | Trunk config (allowed, native, switch side mode), sub interfaces in the correct VLAN / subnet. |
| If STP blocks loops between switches, how do you get increased bandwidth between them? | EtherChannel, bundle ports to get higher bandwidth. |
| If a link that is bundled in etherchannel goes down, does EtherChannel remain up? | Yes, the channel remains, the bandwidth of the channel will be affected however. |
| If a link in an EtherChannel bundle goes down and later comes back up, does it return to the channel? | Yes, it will be automatically placed back into the channel. |
| Do you need to have EtherChannel set to trunk for it to function properly? | No, it can be used on access ports. |
| How many ports can be bundled through EtherChannel? | 8 |
| EtherChannel: port channel mode is set to Auto, what does this mean? | Auto means it is PAgP and it is NOT actively seeking to become a channel |
| EtherChannel: port channel mode is set to Active, what does this mean? | Active means it is LACP and it IS actively seeking to become a channel |
| EtherChannel: port channel mode is set to Desirable, what does this mean? | Desirable means it is PAgP and it IS actively seeking to become a channel |
| EtherChannel: port channel mode is set to Passive, what does this mean? | Passive means it is LACP and it is NOT actively seeking to become a channel |
| EtherChannel: port channel mode is set to on, what does this mean? | On means it is forced, using forced can lead to serious issues if there are config problems. |
| Where does PAgP / LACP channel config communication get sent on? | The Native VLAN |
| STP Costs using EtherChannel? | 100Mb = 19, 2x = 9, 6x or > = 5 ... Even if a link in the bundle goes down the cost does NOT automatically update. |
| Which MAC address does the virtual router use with HSRP? | Virtual MAC address. |
| If a router or link fails when using HSRP and the active router has to switch, what happens to the end devices using the old router? | Nothing changes in the end devices perspective, it is completely transparent. |
| HSRP is the Cisco proprietary protocol, what is the standard protocol? | VRRP |
| In HSRP wich router takes priority? | The one with the HIGHER priority value. |
| If there is no preempt configured with HSRP, which router will become active? | The one which boots first. |
| What is GLBP? | Gateway Load Balancing Protocol, like HSRP but handles load balancing better. Still CISCO! |
| When configuring router sub interface, can you configure the ip address before configuring the encapsulation? | No, you must configure the encapsulation before the IP address can be added. |
Created by:
Datheral
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