350-501 · Question #284
A network administrator is planning a new network with a segment-routing architecture using a distributed control plane. How is routing information distributed on such a network?
The correct answer is D. Each segment is signalled by a compatible routing protocol and each segment makes its own. In a segment routing network utilizing a distributed control plane, routing information is disseminated through compatible routing protocols, with each segment (node) independently making its own forwarding decisions.
Question
A network administrator is planning a new network with a segment-routing architecture using a distributed control plane. How is routing information distributed on such a network?
Options
- AEach segment is signalled by an SR controller, but each segment makes Its own steering
- BEach segment is signalled by MPLS, and each segment makes steering decisions based on the
- CEach segment is signalled by an SR controller that makes the steering decisions for each node.
- DEach segment is signalled by a compatible routing protocol and each segment makes its own
How the community answered
(34 responses)- A3% (1)
- B3% (1)
- C6% (2)
- D88% (30)
Why each option
In a segment routing network utilizing a distributed control plane, routing information is disseminated through compatible routing protocols, with each segment (node) independently making its own forwarding decisions.
An SR controller would imply a centralized control plane, which contradicts the 'distributed control plane' mentioned in the question.
While segment routing can use an MPLS data plane, the actual signaling and distribution of segment routing information is performed by IGPs or BGP, not directly by MPLS.
An SR controller making steering decisions for each node describes a centralized control plane model, not a distributed one where nodes independently make decisions.
In a distributed segment routing architecture, Interior Gateway Protocols (IGPs) like OSPF or IS-IS are used to distribute segment identifiers (SIDs) and topology information among all network devices. Each router then leverages this locally available information to determine its forwarding decisions, thereby building its own segment routing tables based on the received SIDs.
Concept tested: Segment Routing distributed control plane operation
Source: https://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/segment-routing/white-paper-c11-738927.html
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