Cisco Updated 300-540 Exam Questions and Answers by zayne

In Cisco data center and cloud-scale designs, adouble-sided vPC(also called vPC-to-vPC) is used when both ends of a Layer 2 port channel are formed by a pair of switches that operate as vPC peers. In this model:

On the aggregation or leaf side, two switches (in this case,LEAF1 and LEAF2) form a vPC domain with a vPC peer-link and keepalive.

On the access or ToR side, two switches (in this case,TOR1 and TOR2) must also form their ownvPC domainwith a peer-link and vPC keepalive.

The port-channel that interconnects the two vPC domains is then configured as a vPC on both sides, creating a vPC-to-vPC topology.

The problem statement specifies thatLEAF1 and LEAF2 are already configured as vPC peers. For a double-sided vPC to work, the other side (TOR1 and TOR2) must also behave as a single logical entity for the downstream Cisco UCS server and for the upstream vPC connection towards LEAF1 and LEAF2. This is only achieved when TOR1 and TOR2 are configured as vPC peers with:

A vPC domain ID

A vPC peer-link between TOR1 and TOR2

vPC member port-channels towards LEAF1 and LEAF2 and towards the Cisco UCS server

Therefore, the next required step is to configure avPC between TOR1 and TOR2.

Evaluation of the options:

Option A, “Add all the switches to the fabric,” is generic and not specific to vPC configuration. It does not address the technical requirement to form a vPC domain on the ToR side.

Option B, “Configure peering between LEAF1 and LEAF2 and TOR1 and TOR2,” is incorrect because vPC peering is only configured between the two switches that form each vPC domain (LEAF1–LEAF2 and TOR1–TOR2), not across all four switches together.

Option C, “Configure MSTP between TOR1 and TOR2,” is not required for establishing a double-sided vPC. vPC designs rely on the vPC control plane and the peer-link, not on spanning-tree between the vPC peers for normal operation.

Option D, “Configure a vPC between TOR1 and TOR2,” correctly describes configuring TOR1 and TOR2 as a vPC pair (vPC domain with peer-link), which is the mandatory step to create a double-sided vPC topology with LEAF1 and LEAF2.

Comprehensive and Detailed Explanation From Exact Extract from my knowledge of Designing and Implementing Cisco Service Provider Cloud Network Infrastructure Outlines without Any External URL or Links:

Cisco+ Hybrid Cloud is Cisco’s as-a-service consumption model that offers pay-as-you-go infrastructure. For ahybrid workplace, the focus is on giving users secure desktop environments from anywhere, with the ability torapidly deployandscale up or downbased on the number of users or partners.

Cisco+Hybrid Cloud for Virtual Desktop Infrastructure (VDI)specifically delivers desktop and app workspaces as an on-demand service. It allows partners to consume desktops elastically, paying for capacity as needed and scaling the underlying compute, storage, and networking without rebuilding the environment.

Bare Metal Compute and Virtualization offers flexible infrastructure but are aimed at app/workload hosting rather than user desktop workspaces.

Service Provider Networking addresses network services, not end-user hybrid workplace desktops.Therefore, for a pay-as-you-go, rapidly deployable, elastic solution in a hybrid workplace,Cisco+ Hybrid Cloud for Virtual Desktop Infrastructureis the correct choice.

Comprehensive and Detailed Explanation Based on Designing and Implementing Cisco Service Provider Cloud Network Infrastructure Knowledge

When connectingcarrier-neutral facilities (CNFs)ordata centerswithin the same metropolitan area, service providers typically usehigh-bandwidth, low-latency optical transport methods. The most appropriate and commonly deployed interconnection technology is:

DWDM (Dense Wavelength Division Multiplexing) ring, which provides:

High capacity (10G, 40G, 100G, 400G)

Low latency

Redundancy through ring or mesh topologies

Multi-wavelength multiplexing for cost efficiency

Carrier-grade reliability for metro interconnect services

This aligns with cloud interconnect and metro transport design used in service provider environments.

Evaluation of the Options

A. OSPF backbone area adjacency

This is a routing protocol adjacency, not a physical connection method. It requires a transport link underneath but does not represent the physical interconnect itself.

B. Private wireless connection

Not suitable for CNF or metro DC interconnect because it lacks the bandwidth, reliability, and deterministic performance required for large-scale carrier-grade interconnects.

C. DWDM ring

This is the correct method. DWDM-based metro fiber rings are the standard for connecting carrier-neutral facilities in the same metro region.

D. CAT6e connection

This is limited to short-distance copper Ethernet (tens of meters). It is not used for metro-scale interconnects or between CNFs.

In the diagram, thePE and R2, R3, R4, R5belong toAS 100. The PE router runs BGP processAS 100, so its BGP configuration must start with:

router bgp 100

To performiBGP multipath load sharingacross three equal-cost internal BGP paths, BGP must be instructed to keep and use multiple iBGP paths in the routing table. This is done with:

router bgp 100

maximum-paths ibgp 3

maximum-paths ibgp 3 tells BGP to install up tothreeiBGP paths to the same prefix, enabling CEF to load-share across those paths.

router bgp 100 is required because the PE is inAS 100, not 101.

Other options:

ip load-sharing per-destination affects CEF behavior but does not enable BGP iBGP multipath by itself and is not specific to three iBGP paths.

ip load-sharing ibgp 3 is not a valid IOS BGP command.

router bgp 101 would configure the wrong AS and break the iBGP relationships shown in AS-100.

Thus, the correct commands on the PE to achieve iBGP multipath load sharing over the three internal paths aremaximum-paths ibgp 3androuter bgp 100, corresponding toA and E.