Exam JN0-683 topic 2 question 9 discussion

two correct statements are: C. The multipath multiple-as statement is required to enable ECMP if every device has a different AS number. D. Only a single point to point EBGP session is required between peers in an IP fabric. Statement C is correct because in an IP fabric where each device uses a unique AS number, the "multipath multiple-as" statement is essential to enable ECMP (Equal-Cost Multi-Path). Without this configuration, BGP would typically only consider paths from the same AS for load balancing. Statement D is correct because IP fabrics use a simple connectivity model where only one EBGP session is needed between any two devices (like between a leaf and spine). Additional sessions would be unnecessary and inefficient. The other statements are incorrect: Statement A is wrong because EBGP is used for internal fabric connectivity, not just external routing Statement B is wrong because using the same AS number on all leaf devices would require special configurations to prevent route rejection

It is possible for all leaf devices in an IP fabric to use the same AS number. In fact, this is a common configuration, particularly in designs where all leaf devices within a particular POD or area share the same routing policy and AS. In a Same-Tier-AS IP fabric, all leaf devices can typically share the same AS number without requiring adjustments to the EBGP configuration. In this design, all spine switches use a different, unique AS number, and all leaf switches also share a unique AS number distinct from the spine switches. https://www.juniper.net/documentation/us/en/software/nce/sg-005-data-center-fabric/topics/task/5-stage-ip-fabric-cloud-dc-configuring.html https://www.cisco.com/c/en/us/td/docs/dcn/ndfc/1221/articles/ndfc-managing-bgp-based-routed-fabrics/managing-bgp-based-routed-fabrics.html