Home > SDM Questions

SDM Questions

November 27th, 2019 Go to comments
SDM Quick summary

SDM templates are used to configure system resources in the switch to optimize support for specific features, depending on how the switch is used in the network. You can select a template to provide maximum system usage for some functions or use the default template to balance resources.

To allocate ternary content addressable memory (TCAM) resources for different usages, the switch SDM templates prioritize system resources to optimize support for certain features. You can select SDM templates to optimize these features:
+ Access – The access template maximizes system resources for access control lists (ACLs) to accommodate a large number of ACLs.
+ Default – The default template gives balance to all functions.
+ Routing – The routing template maximizes system resources for IPv4 unicast routing, typically required for a router or aggregator in the center of a network.
+ VLANs – The VLAN template disables routing and supports the maximum number of unicast MAC addresses. It would typically be selected for a Layer 2 switch.

In addition, the dual IPv4 and IPv6 templates enable a dual stack environment.

In order to configure SDM template, use this command under global configuration mode: sdm prefer {access | default | dual-ipv4-and-ipv6 {default | routing | vlan} | routing | vlan}.
For example: Switch(config)# sdm prefer routing or Switch(config)# sdm prefer dual-ipv4-and-ipv6 default

Command to verify SDM template: show sdm prefer

In a switch stack, SDM template is stored in the master switch.

Question 1

Explanation

SDM templates are used to configure system resources in the switch to optimize support for specific features, depending on how the switch is used in the network. You can select a template to provide maximum system usage for some functions or use the default template to balance resources.

To allocate ternary content addressable memory (TCAM) resources for different usages, the switch SDM templates prioritize system resources to optimize support for certain features. You can select SDM templates to optimize these features:
+ Access – The access template maximizes system resources for access control lists (ACLs) to accommodate a large number of ACLs.
+ Default – The default template gives balance to all functions.
+ Routing – The routing template maximizes system resources for IPv4 unicast routing, typically required for a router or aggregator in the center of a network.
+ VLANs – The VLAN template disables routing and supports the maximum number of unicast MAC addresses. It would typically be selected for a Layer 2 switch.

In addition, the dual IPv4 and IPv6 templates enable a dual stack environment.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/release/12-2_55_se/configuration/guide/scg3750/swsdm.html

Question 2

Explanation

The VLAN template disables routing and supports the maximum number of unicast MAC addresses. It would typically be selected for a Layer 2 switch.

Question 3

Explanation

The VLAN template disables routing and supports the maximum number of unicast MAC addresses. It would typically be selected for a Layer 2 switch.

Question 4

Explanation

The VLAN template disables routing and supports the maximum number of unicast MAC addresses. It would typically be selected for a Layer 2 switch only. But in this case this switch is also used for routing. The VLAN template disabled routing feature so all routing processing is sent to the CPU, seriously impacting switch performance, causing the CPU of the switch to spike, especially during peak hours.

Question 5

Question 6

Question 7

Explanation

In fact there are only three correct choices in this question but we listed here all four correct answers so that you can see which ones are not correct.

SDM templates are used to configure system resources in the switch to optimize support for specific features, depending on how the switch is used in the network. You can select a template to provide maximum system usage for some functions or use the default template to balance resources.

To allocate ternary content addressable memory (TCAM) resources for different usages, the switch SDM templates prioritize system resources to optimize support for certain features. You can select SDM templates to optimize these features:
+ Access – The access template maximizes system resources for access control lists (ACLs) to accommodate a large number of ACLs.
+ Default – The default template gives balance to all functions.
+ Routing – The routing template maximizes system resources for IPv4 unicast routing, typically required for a router or aggregator in the center of a network.
+ VLANs – The VLAN template disables routing and supports the maximum number of unicast MAC addresses. It would typically be selected for a Layer 2 switch.

In addition, the dual IPv4 and IPv6 templates enable a dual stack environment.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/release/12-2_55_se/configuration/guide/scg3750/swsdm.html

Question 8

Question 9

Question 10

Question 11

Comments
  1. georoot
    January 14th, 2020

    q7
    4 answers are correct, but the real question says choose three.
    what do you do?

  2. Q4
    January 16th, 2020

    The switch supports an IP Base software image (with or without payload encryption) for customers without a service support contract. This image supports the IP Base and LAN Base feature sets.

    LAN Base feature set—Provides basic Layer 2+ features, including access control lists (ACLs) and quality of service (QoS). Starting with Cisco IOS Release 12.2(58)SE, the LAN Base feature set also supports static IP routing on switch virtual interfaces (SVIs) for 16 user-configured routes.

    https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/15-0_2_se/configuration/guide/3750x_cg/swintro.html

    Choosing the VLAN template will actually disable routing (number of entry for unicast or multicast route is zero) in hardware.

    https://www.cisco.com/c/en/us/support/docs/switches/catalyst-3750-series-switches/44921-swdatabase-3750ss-44921.html

    Q4 Answer C is correct!

  3. Suntzu
    January 17th, 2020

    A network engineer deployed a switch that operates the LAN base feature set and decides to use the SDM VLAN template

    REGARDLESS IF IT DISABLES HARDWARE BASED ROUTING 10% 50%, 70% OR 100%, the fact remains that it does in fact reduce routing in hardware and pushes it to the CPU.

    C is correct no matter how you look at it. SDM VLAN tells ASICS to only look at increase VLAN performance. Routing then has to go somewhere. It goes to the CPU!!

  4. ricky
    February 15th, 2020

    hi anyone have a switch dump pls share k6206700 at gmail dot com

  1. No trackbacks yet.