nerdexam
Cisco

300-415 · Question #224

After deploying Cisco SD-WAN, the company realized that by default, all sites built direct IPsec VPN tunnels to each other. In their previous topology, all spoke sites used the head office as their…

The correct answer is C. Manage Preference and Prefix Lists; 'All hubs are equal' checkbox checked; 'Advertise Hub TLOCs' checkbox checked; 'Prefix Lists (Optional)' field is empty; 'Spoke Sites' associated with 'Hub Sites'; 'Hub' associated with 'Spokes'; 'LAN_Segment X' tag. To transition from a full-mesh topology to a hub-and-spoke model where spokes route to a head office for a specific LAN segment, you need to configure a centralized topology policy. This policy involves explicitly defining hub and spoke sites and ensuring that the 'Advertise…

Policies

Question

After deploying Cisco SD-WAN, the company realized that by default, all sites built direct IPsec VPN tunnels to each other. In their previous topology, all spoke sites used the head office as their next hop for the LAN segment that belongs to network 40.0.0.0/16. The company wants to deploy its previous policy, which allows the 40.0.0.0/16 network that originates at the hub to advertise to the spokes. Which configuration meets the requirement?

Exhibit

300-415 question #224 exhibit

Options

  • AManage Preference and Prefix Lists; 'All hubs are equal' checkbox unchecked; 'Advertise Hub TLOCs' checkbox checked; 'Prefix Lists (Optional)' field is empty; 'Spoke Sites' associated with 'Hub Sites'; 'Hub' associated with 'Spokes'; 'LAN_Segment X' tag.
  • BManage Preference and Prefix Lists; 'All hubs are equal' checkbox checked; 'Advertise Hub TLOCs' checkbox unchecked; 'Prefix Lists (Optional)' field is empty; 'Spoke Sites' associated with 'Hub Sites'; 'Hub' associated with 'Spokes'; 'LAN_Segment X' tag.
  • CManage Preference and Prefix Lists; 'All hubs are equal' checkbox checked; 'Advertise Hub TLOCs' checkbox checked; 'Prefix Lists (Optional)' field is empty; 'Spoke Sites' associated with 'Hub Sites'; 'Hub' associated with 'Spokes'; 'LAN_Segment X' tag.
  • DManage Preference and Prefix Lists; 'All hubs are equal' checkbox checked; 'Advertise Hub TLOCs' checkbox checked; 'Prefix Lists (Optional)' field shows 'Select one or more prefix lists'; 'Spoke Sites' associated with 'Hub Sites'; 'Hub' associated with 'Spokes'; 'LAN_Segment X' tag.

How the community answered

(52 responses)
  • A
    8% (4)
  • B
    15% (8)
  • C
    73% (38)
  • D
    4% (2)

Why each option

To transition from a full-mesh topology to a hub-and-spoke model where spokes route to a head office for a specific LAN segment, you need to configure a centralized topology policy. This policy involves explicitly defining hub and spoke sites and ensuring that the 'Advertise Hub TLOCs' option is checked, allowing hub routes to be propagated to spokes.

AManage Preference and Prefix Lists; 'All hubs are equal' checkbox unchecked; 'Advertise Hub TLOCs' checkbox checked; 'Prefix Lists (Optional)' field is empty; 'Spoke Sites' associated with 'Hub Sites'; 'Hub' associated with 'Spokes'; 'LAN_Segment X' tag.

Unchecking 'All hubs are equal' is typically used in multi-hub scenarios where preferences are needed, not for simply advertising hub routes to spokes in a basic hub-and-spoke setup.

BManage Preference and Prefix Lists; 'All hubs are equal' checkbox checked; 'Advertise Hub TLOCs' checkbox unchecked; 'Prefix Lists (Optional)' field is empty; 'Spoke Sites' associated with 'Hub Sites'; 'Hub' associated with 'Spokes'; 'LAN_Segment X' tag.

Unchecking 'Advertise Hub TLOCs' would prevent the hub's TLOCs (and thus its routes) from being advertised to the spokes, which would break the desired hub-and-spoke routing where spokes need to learn routes from the hub.

CManage Preference and Prefix Lists; 'All hubs are equal' checkbox checked; 'Advertise Hub TLOCs' checkbox checked; 'Prefix Lists (Optional)' field is empty; 'Spoke Sites' associated with 'Hub Sites'; 'Hub' associated with 'Spokes'; 'LAN_Segment X' tag.Correct

To implement a hub-and-spoke topology where spokes route through the hub, you need to mark the relevant sites as 'Hub Sites' and 'Spoke Sites'. The 'All hubs are equal' checkbox being checked is suitable for a single-hub scenario, and crucially, 'Advertise Hub TLOCs' must be checked so that the spokes learn routes and TLOCs from the hub, enabling them to direct traffic towards the hub for the 40.0.0.0/16 network.

DManage Preference and Prefix Lists; 'All hubs are equal' checkbox checked; 'Advertise Hub TLOCs' checkbox checked; 'Prefix Lists (Optional)' field shows 'Select one or more prefix lists'; 'Spoke Sites' associated with 'Hub Sites'; 'Hub' associated with 'Spokes'; 'LAN_Segment X' tag.

While 'Advertise Hub TLOCs' is checked, the 'Prefix Lists (Optional)' field suggesting that a prefix list is selected could unintentionally filter the 40.0.0.0/16 network or add unnecessary complexity, whereas the requirement is to advertise it directly.

Concept tested: Cisco SD-WAN Hub-and-Spoke Topology Policy

Source: https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/sdwan-xe-gs-book/sdwan-policies.html#concept_f5j_3j4_zbb

Topics

#SD-WAN Policies#Hub-and-Spoke Topology#Control Policy#TLOCs

Community Discussion

No community discussion yet for this question.

Sign up to join the discussion
Full 300-415 Practice