Which command is used to enable EtherChannel hashing for Layer 3 IP and Layer 4 port-based CEF?
A. mpls ip cef
B. port-channel ip cef
C. mpls ip port-channel cef
D. port-channel load balance
E. mpls ip load-balance
F. ip cef EtherChannel channel-id XOR L4
G. ip cef connection exchange
Correct Answer: D Section: (none) Explanation
Port-channel load balance is normally used for enable etherchannel hashing for Layer 3 IP and Layer 4
port based CEF.
Which two statements are true about traffic shaping? (Choose two.)
A. Out-of-profile packets are queued.
B. It causes TCP retransmits.
C. Marking/remarking is not supported.
D. It does not respond to BECN and ForeSight Messages.
E. It uses a single/two-bucket mechanism for metering.
Correct Answer: AC Section: (none) Explanation
Reference: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCwQFjAA&url=htt p%3A %2F%2Fstaffweb.itsligo.ie%2Fstaff%2Fpflynn%2FTelecoms%25203%2FSlides%2FONT%2 520Mod% 25204%2520Lesson%25207.ppt&ei=LoDIUfTTGtO3hAeQz4HQCA&usg=AFQjCNGY24 UkAfy8tKIHlzEm9gfoIjv6fg&sig2=t4UIzkZ12wnO2988dEDyug&bvm=bv.48293060,d.ZG4 (slide 6)
Which three options are features of VTP version 3? (Choose three.)
A. VTPv3 supports 8K VLANs.
B. VTPv3 supports private VLAN mapping.
C. VTPv3 allows for domain discovery.
D. VTPv3 uses a primary server concept to avoid configuration revision issues.
E. VTPv3 is not compatible with VTPv1 or VTPv2.
F. VTPv3 has a hidden password option.
Correct Answer: BDF Section: (none) Explanation
Explanation: Key Benefits of VTP Version 3 Much work has gone into improving the usability of VTP version 3 in three major areas: The new version of VTP offers better administrative control over which device is allowed to update other devices’ view of the VLAN topology. The chance of unintended and disruptive changes is significantly reduced, and availability is increased. The reduced risk of unintended changes will ease the change process and help speed deployment. Functionality for the VLAN environment has been significantly expanded. Two enhancements are most beneficial for today’s networks:
In addition to supporting the earlier ISL VLAN range from 1 to 1001, the new version supports the whole IEEE 802.1Q VLAN range up to 4095.
In addition to supporting the concept of normal VLANs, VTP version 3 can transfer information regarding Private VLAN (PVLAN) structures. The third area of major improvement is support for databases other than VLAN (for example, MST).
Brief Background on VTP Version 1 and VTP Version 2 VTP version 1 was developed when only 1k VLANs where available for configuration. A tight internal coupling of the VLAN implementation, the VLAN pruning feature, and the VTP function itself offered an efficient means of implementation. It has proved in the field to reliably support Ethernet, Token Ring, and FDDI networks via VTP. The use of consistent VLAN naming was a requirement for successful use of VMPS (Vlan Membership Policy Server). VTP ensures the consistency of VLAN names across the VTP domain. Most VMPS implementations are likely to be migrated to a newer, more flexible and feature-rich method. To add support for Token Ring, VTP version 1 was enhanced and called VTP version 2. Certain other minor changes and enhancements were also added at this time. The functional base in VTP version 3 is left unchanged from VTP version 2, so backward compatibility is built in. It is possible, on a per link basis, to automatically discover and support VTP version 2 devices.
VTP version 3 adds a number of enhancements to VTP version 1 and VTP version 2: Support for a structured and secure VLAN environment (Private VLAN, or PVLAN) Support for up to 4k VLANs Feature enhancement beyond support for a single database or VTP instance Protection from unintended database overrides during insertion of new switches Option of clear text or hidden password protection Configuration option on a per port base instead of only a global scheme Optimized resource handling and more efficient transfer of information These new requirements made a new code foundation necessary. The design goal was to make VTP version 3 a versatile vehicle. This was not only for the task of transferring a VLAN DB but also for transferring other databases-for example, the MST database.
Reference http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/solution_guide_c78_508010.ht ml
Which three options are considered in the spanning-tree decision process? (Choose three.)
A. lowest root bridge ID
B. lowest path cost to root bridge
C. lowest sender bridge ID
D. highest port ID
E. highest root bridge ID
F. highest path cost to root bridge
Correct Answer: ABC Section: (none) Explanation
Explanation: Configuration bridge protocol data units (BPDUs) are sent between switches for each port. Switches use s four step process to save a copy of the best BPDU seen on every port. When a port receives a better BPDU, it stops sending them. If the BPDUs stop arriving for 20 seconds (default), it begins sending them again.
Step 1 Lowest Root Bridge ID (BID) Step 2 Lowest Path Cost to Root Bridge Step 3 Lowest Sender BID Step 4 Lowest Port ID
Reference Cisco General Networking Theory Quick Reference Sheets
In 802.1s, how is the VLAN to instance mapping represented in the BPDU?
A. The VLAN to instance mapping is a normal 16-byte field in the MST BPDU.
B. The VLAN to instance mapping is a normal 12-byte field in the MST BPDU.
C. The VLAN to instance mapping is a 16-byte MD5 signature field in the MST BPDU.
D. The VLAN to instance mapping is a 12-byte MD5 signature field in the MST BPDU.
Correct Answer: C Section: (none)Explanation
MST Configuration and MST Region
Each switch running MST in the network has a single MST configuration that consists of these three
An alphanumeric configuration name (32 bytes)
A configuration revision number (two bytes)
A 4096-element table that associates each of the potential 4096 VLANs supported on the chassis to a given instance.
In order to be part of a common MST region, a group of switches must share the same configuration attributes. It is up to the network administrator to properly propagate the configuration throughout the region. Currently, this step is only possible by the means of the command line interface (CLI) or through Simple Network Management Protocol (SNMP). Other methods can be envisioned, as the IEEE specification does not explicitly mention how to accomplish that step. Note: If for any reason two switches differ on one or more configuration attribute, the switches are part of different regions. For more information refer to the Region Boundary section of this document.
Region Boundary In order to ensure consistent VLAN-to-instance mapping, it is necessary for the protocol to be able to exactly identify the boundaries of the regions. For that purpose, the characteristics of the region are included in the BPDUs. The exact VLANs-to-instance mapping is not propagated in the BPDU, because the switches only need to know whether they are in the same region as a neighbor.
Therefore, only a digest of the VLANs-toinstance mapping table is sent, along with the revision number and the name. Once a switch receives a BPDU, the switch extracts the digest (a numerical value derived from the VLAN-to-instance mapping table through a mathematical function) and compares this digest with its own computed digest. If the digests differ, the port on which the BPDU was received is at the boundary of a region. In generic terms, a port is at the boundary of a region if the designated bridge on its segment is in a different region or if it receives legacy 802.1d BPDUs. In this diagram, the port on B1 is at the boundary of region A, whereas the ports on B2 and B3 are internal to region B: MST Instances According to the IEEE 802.1s specification, an MST bridge must be able to handle at least these two instances: One Internal Spanning Tree (IST) One or more Multiple Spanning Tree Instance(s) (MSTIs) The terminology continues to evolve, as 802.1s is actually in a pre-standard phase. It is likely these names will change in the final release of 802.1s. The Cisco implementation supports 16 instances: one IST (instance 0) and 15 MSTIs.
show vtp status Cisco switches “show vtp status” Field Descriptions has a MD5 digest field that is a 16-byte checksum of the VTP configuration as shown below Router# show vtp status VTP Version: 3 (capable) Configuration Revision: 1 Maximum VLANs supported locally: 1005 Number of existing VLANs: 37 VTP Operating Mode: Server VTP Domain Name: [smartports] VTP Pruning Mode: Disabled VTP V2 Mode: Enabled VTP Traps Generation: Disabled
“Pass Any Exam. Any Time.” – www.actualtests.com 11 Cisco 350-001 Exam
MD5 digest : 0x26 0xEE 0x0D 0x84 0x73 0x0E 0x1B 0x69 Configuration last modified by 172.20.52.19 at 7-25-08 14:33:43 Local updater ID is 172.20.52.19 on interface Gi5/2 (first layer3 interface fou) VTP version running: 2
Reference http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cfc.shtml http:// www.cisco.com/en/US/docs/ios-xml/ios/lanswitch/command/lsw-cr-book.pdf
While you are troubleshooting network performance issues, you notice that a switch is periodically flooding all unicast traffic. Further investigation reveals that periodically the switch is also having spikes in CPU utilization, causing the MAC address table to be flushed and relearned. What is the most likely cause of this issue?
A. a routing protocol that is flooding updates
B. a flapping port that is generating BPDUs with the TCN bit set
C. STP is not running on the switch
D. a user that is downloading the output of the show-tech command
E. a corrupted switch CAM table
Correct Answer: B Section: (none) Explanation
Explanation: Spanning-Tree Protocol Topology Changes Another common issue caused by flooding is Spanning-Tree Protocol (STP) Topology Change Notification (TCN). TCN is designed to correct forwarding tables after the forwarding topology has changed. This is necessary to avoid a connectivity outage, as after a topology change some destinations previously accessible via particular ports might become accessible via different ports. TCN operates by shortening the forwarding table aging time, such that if the address is not relearned, it will age out and flooding will occur. TCNs are triggered by a port that is transitioning to or from the forwarding state. After the TCN, even if the particular destination MAC address has aged out, flooding should not happen for long in most cases since the address will be relearned. The issue might arise when TCNs are occurring repeatedly with short intervals. The switches will constantly be fast-aging their forwarding tables so flooding will be nearly constant. Normally, a TCN is rare in a well-configured network. When the port on a switch goes up or down, there is eventually a TCN once the STP state of the port is changing to or from forwarding. When the port is flapping, repetitive TCNs and flooding occurs. Ports with the STP portfast feature enabled will not cause TCNs when going to or from the forwarding state. Configuration of portfast on all end-device ports (such as printers, PCs, servers, and so on) should limit TCNs to a low amount. Refer to this document for more information on TCNs: Understanding Spanning-Tree Protocol Topology Changes Note: In MSFC IOS, there is an optimization that will trigger VLAN interfaces to repopulate their ARP tables when there is a TCN in the respective VLAN. This limits flooding in case of TCNs, as there will be an ARP broadcast and the host MAC address will be relearned as the hosts reply to ARP.
Reference http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a00801d0808. shtml
When troubleshooting the issue, you notice the election of a new root bridge with an unknown MAC address. Knowing that all access ports have the PortFast feature enabled, what would be the easiest way to resolve the issue without losing redundant links?
A. Enable bpduguard globally.
B. Enable rootguard.
C. Enable loopguard.
D. Enable spanning tree.
E. Enable UDLD.
Correct Answer: A Section: (none)Explanation
Loopguard, spanning tree, and UDLD are obvious red herrings. This leaves enabling rootguard or
bpduguard. One key is that enabling bpduguard only affects ports that have portfast enabled; see the
following URL under “Configuration.”
Which two statements are true about 802.1s? (Choose two.)
A. 802.1s supports a reduced number of spanning-tree instances.
B. 802.1s has better convergence times than 802.1w.
C. 802.1s does not support load balancing over the same physical topology.
D. The CPU utilization for 802.1s is lower than the CPU utilization for 802.1w.
Correct Answer: AD Section: (none)Explanation Explanation/Reference:
Which configuration is used to enable root guard?
A. interface gig3/1 spanning-tree guard root
B. interface gig3/1 spanning-tree root guard
C. interface gig3/1 spanning-tree root-guard
D. interface gig3/1 spanning-tree root-guard default
Correct Answer: A Section: (none)Explanation
Which two statements describe spanning-tree BPDU processing for a blocking port? (Choose two.)
A. BPDUs that enter a blocking port are discarded.
B. BPDUs that enter a blocking port are processed.
C. Loopguard puts an interface into a loop-inconsistent state when BPDUs stop being received on a blocking port.
D. BPDUs are only processed on forwarding ports.
Correct Answer: BC Section: (none) Explanation