Connect. Secure. Manage.
Cisco Nexus Troubleshooting
Investigate Cisco Nexus switching and routing faults using interface evidence, control-plane state, forwarding behaviour and the affected application paths.
Devices supported
across the UK
Client locations
supported
Traffic handled
at peak time
Average
response time
Average response is not a resolution time or a contractual guarantee. Support scope and response commitments are agreed for each engagement.
Cisco Nexus troubleshooting is most effective when it follows an affected application path rather than a random sequence of device commands. A healthy switch process or an interface marked up does not prove that traffic is being forwarded correctly. MCI Network Services investigates Nexus switching and routing faults using physical evidence, control-plane state and the actual forwarding design. We help customers isolate the cause without making unrelated changes that obscure the original problem.
Workload-led design
Start with application, compute and storage dependencies rather than the switch model.
Clear failure domains
Understand which links, devices and sites can fail together.
Operational clarity
Make fabrics, external routing and management responsibilities supportable.
Define the fault precisely
We establish which source and destination systems are affected, whether the problem is constant or intermittent and what changed before it began. The symptom may concern one VLAN, one server bond, one routed path or a wider fabric. Comparing working and failing services helps identify the boundary of the incident before disruptive action is considered.
The timeline includes application records, monitoring events and recent configuration or software changes. Clocks and time zones are reconciled before evidence is compared. We distinguish the first observed alarm from the actual start of service impact and note where historical data is missing. An investigation should not manufacture precision that the available records cannot support.
Standards & partnerships
Confidence in the team behind your network.
Cisco Partner
Cisco Meraki
Cyber Essentials
Cyber Essentials PlusMCI Network Services is operated by Proxar Ltd. Certifications apply to the certified legal entity and the scope of its certificates. View accreditation information
Check the physical and interface layer
We review link state, errors, discards, optics and port-channel membership on the relevant path. A physical link can remain up while experiencing errors or congestion, and an aggregated connection can continue passing some traffic with an inconsistent member. The interpretation depends on the counters supported by the specific Nexus hardware and release.
Server-side evidence is included where a host or virtual switch is involved. NIC bonding mode, VLAN tagging and MTU can create faults that look like switching problems. We coordinate with the platform team rather than treating a successful switch-to-switch ping as proof that the network is unrelated. The goal is to examine the combined service, not to pass responsibility between teams.
A useful starting point
Not sure where to start?
Bring the requirement. We will help you define the engineering work.
Trace switching, routing and policy state
For Layer 2 faults, we compare VLAN presence, MAC learning, trunk allowances and spanning-tree behaviour with the intended topology. For routed traffic, we examine neighbours, next hops and the installed forwarding state. The route visible in a control-plane table must correspond to a usable path through the actual interfaces and security boundaries.
vPC and fabric deployments require their own context. Peer communication, consistency checks, endpoint learning and overlay routes may influence the result. We use the architecture-specific evidence relevant to the failure rather than applying a generic checklist indiscriminately. Where the problem belongs in an ACI or EVPN investigation, the scope follows that architecture and its operational model.
Different environments. The same care.
Built around the work
your network supports.
Finance, banking and the wider private sector. We start with the systems and people that depend on your connections.
Finance & banking
Market-data paths, routing and provider coordination on clients’ behalf.
Financial-market services ↗Offices & multi-site teams
Reliable access between people, workplaces and business applications.
Office network design ↗Data centres & cloud
Network boundaries, workload connections and operational ownership.
Data centre networks ↗Investigate intermittent and load-dependent failures
Intermittent faults need measurements that capture the conditions under which they occur. Coarse utilisation averages can miss bursts, and a quiet test may not exercise the same queue or path as production traffic. We review available telemetry and agree targeted collection where more evidence is required. Diagnostic activity is limited to avoid adding unnecessary load to an already unstable system.
Packet captures or platform diagnostics are used only with suitable authorisation and an understanding of their limitations. We account for capture drops, mirrored-traffic behaviour and sensitive payloads. A missing packet at one observation point does not by itself identify the upstream device responsible. Findings state what the evidence proves and what remains an inference.
Make corrective changes with a clear hypothesis
Each proposed change should address an identified cause or test a specific explanation. We document the expected result, service risk and rollback condition. Broad resets, clearing all neighbours or disabling protection features are not default first responses. They can temporarily hide a fault while interrupting other services and destroying useful evidence.
Where a vendor defect is suspected, we assemble the relevant platform, release and diagnostic information for an authorised support escalation. We do not declare a software bug merely because the configuration looks reasonable. Hardware, policy and application dependencies are considered alongside release information, and the customer is told how confident the diagnosis is before a disruptive upgrade or replacement is proposed.
Verify recovery and retain the lesson
After remediation, we repeat representative tests and compare the result with the incident evidence. The report separates root cause, contributing conditions, workaround and permanent corrective action. Monitoring or documentation gaps discovered during the investigation become specific follow-up tasks. A useful incident review makes the next fault easier to recognise and less likely to recur.
MCI can assist with a focused Nexus fault, an inherited unstable environment or a problem involving several technical teams. Our Cisco Nexus switching service also covers design and lifecycle improvements where the investigation identifies a wider issue. Share the affected paths, approximate timing and available records through an agreed secure channel; live access and disruptive tests are separately authorised and scoped.
Talk to a specialist
What does your network need next?
Tell us what you are planning, changing or trying to improve. We will help define a practical next step and the engineering scope.
+44 203 196 6566Choose option 1
sales@proxar.co.ukUK-wide service.
Most of our engineers are based in Kent, with a focus on London, Sussex, Essex and Berkshire.
Existing customers should use their agreed support and escalation channels. This form is for service enquiries, not a monitored emergency ticket.
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