352-001 · Question #607
Which MPLS attribute is required for links to carry a given MPLSTE tunnel?
The correct answer is C. Affinity. MPLS TE uses link affinities (administrative groups) to constrain which links a TE tunnel is allowed to traverse, making affinity the required link-level attribute.
Question
Which MPLS attribute is required for links to carry a given MPLSTE tunnel?
Options
- ATE tunnel destination address
- BTunnel path-selection metric
- CAffinity
- DNext-hop backup tunnel
How the community answered
(27 responses)- B4% (1)
- C89% (24)
- D7% (2)
Why each option
MPLS TE uses link affinities (administrative groups) to constrain which links a TE tunnel is allowed to traverse, making affinity the required link-level attribute.
The TE tunnel destination address is a tunnel endpoint configuration parameter, not an attribute assigned to individual links to make them eligible.
Path-selection metric influences which path CSPF selects but is not a link attribute that gates whether a link can carry the tunnel.
Affinity, also called link administrative groups, is configured on physical links and referenced in TE tunnel configurations via an affinity and mask pair. When a TE tunnel has an affinity requirement, CSPF path computation only includes links whose attribute bits satisfy the tunnel's affinity mask, making it the mandatory link attribute that determines eligibility to carry a given TE tunnel.
Next-hop backup tunnel is a Fast Reroute protection construct and is not a prerequisite attribute for a link to carry a primary TE tunnel.
Concept tested: MPLS TE link affinity administrative groups
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mp_te_path_attributes/configuration/xe-16/mp-te-path-attrib-xe-16-book/mp-te-attrib-grps.html
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