Advanced Routing and Traffic Engineering Questions

Advanced routing protocols, algorithms, and real world deployment practices for large scale and multi domain networks. Topics include deep Border Gateway Protocol knowledge such as path selection, attribute handling including weight, local preference, AS path manipulation, multi exit discriminators, communities, route filtering, route aggregation, and mitigation of route hijacking. Also covers advanced aspects of interior protocols such as Open Shortest Path First and IS IS including area design, adjacency and LSA or link state behavior, convergence optimization, and comparison of link state versus other approaches. Traffic engineering topics include load balancing, multi path routing, MPLS fundamentals and label switching, segment routing principles, and using routing and BGP for traffic engineering across internet exchanges and multi carrier environments. Practical skills include designing redundancy, scaling routing control planes, route policy design, and troubleshooting complex inter domain routing behaviors.

EasyTechnical

50 practiced

Describe OSPFv2 LSA types (Type 1 through Type 7). For each LSA type explain where it is originated, the flooding scope (intra-area, inter-area, or AS-wide), and a typical operational use. Include an example area design showing why Type 3 summaries are important and how Type 7 (NSSA) interacts with Type 5.

MediumTechnical

63 practiced

Write a Python 3 script (maximum 50 lines) that reads from stdin simplified BGP entries where each line is: 'prefix local_pref as_path origin' (space-separated). Example: '203.0.113.0/24 100 65001 65002 65003 i'. For each unique prefix, output the best path according to: highest local_pref, then shortest AS path length, then origin preference (i < e < ?), then lexicographically smallest AS path string as final tie-breaker. Focus on correct selection logic and readable code.

EasyTechnical

60 practiced

Explain the BGP path selection process used to pick a single best path. List the attributes evaluated in order (including weight, local-preference, AS path length, origin, MED, eBGP over iBGP, IGP metric to next hop, and router-id/peer tie-breakers). Describe vendor-specific tie-breakers (for example Cisco weight) and walk through a short example with three candidate paths showing which would be selected and why.

MediumTechnical

41 practiced

Explain route aggregation and summarization mechanisms in OSPF and BGP. What are the benefits for control-plane scaling, and what are the risks such as suboptimal routing or blackholing? Describe operational mitigations like selective deaggregation, conditional advertisements, and prefix-length planning.

MediumTechnical

46 practiced

Explain IS-IS adjacency formation including Hello PDUs, DIS election on LANs, and adjacency states. Discuss why IS-IS may be preferred over OSPF in some large-scale networks, touching on protocol extensibility (TLVs), native support for multi-topology and IPv6, and operational differences in level-1/level-2 separation.

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