Network Infrastructure Design and Administration

The network diagram in most small offices reflects whatever happened over the last several years. A switch here, a wireless router there, and the result is a flat Layer 2 mess with no segmentation, unpredictable performance, and nothing documented. Subnet Works fixes that. Whether the job is a ground-up buildout, a switch replacement, or diagnosing a performance problem no one else has been able to track down, the engagement starts with understanding what you actually need and ends with documented, working infrastructure.

Common problems businesses call about

• Network slowdowns at predictable or unpredictable times (often STP topology changes or broadcast storms)
• Adding a second office or floor and not knowing how to extend the network
• Needing to separate guest Wi-Fi from internal systems without buying a second internet connection
• VoIP phones dropping calls or competing with data traffic
• A dying or end-of-life switch that needs to be replaced with minimal downtime
• Connecting two buildings or sites reliably
• Not knowing what is on the network or how it is configured

What the engagement covers

Switching

• Cisco IOS switch configuration (IOS, IOS-XE)
• VLAN design and 802.1Q trunk configuration
• Inter-VLAN routing via Layer 3 switch or router-on-a-stick
• Spanning Tree Protocol: PVST+, Rapid PVST+, root bridge placement, PortFast, BPDU Guard
• EtherChannel (LACP) for uplink and server-facing link aggregation
• Port security: sticky MAC, violation modes, dynamic ARP inspection
• DHCP snooping and IP Source Guard for untrusted access ports

Routing

• Cisco IOS router configuration
• OSPF: single-area and multi-area design, LSA types, DR/BDR election
• Static routing and policy-based routing for multi-WAN setups
• NAT and PAT: overload for outbound traffic, static NAT for DMZ services
• Route redistribution between protocols when needed

Network services

• DHCP server configuration and DHCP relay (ip helper-address)
• DNS administration and split-horizon DNS for internal services
• NTP synchronization across network devices
• Syslog and SNMP for monitoring integration

Quality of Service

• DSCP marking and classification for VoIP and video traffic
• Traffic shaping and policing on WAN-facing interfaces
• Voice VLAN configuration for IP phones

Redundancy and availability

• HSRP and VRRP for default gateway redundancy
• Uplink redundancy with EtherChannel or STP-managed failover
• Dual-WAN configuration with failover or load balancing

Documentation

• Full topology diagram delivered at project close
• Running configuration backup and change log
• Recovery procedure for common failure scenarios

Representative scope examples

New office buildout. A 20-seat professional services firm in Newark needed a segmented network before moving into new space. Subnet Works designed the VLAN topology, configured a Cisco router and managed switches with OSPF for internal routing, set up voice VLANs for IP phones with QoS marking, and handed over a full topology diagram and configuration backup on day one.

Switch replacement with STP cleanup. A 30-person distribution company in Hudson County was running aging unmanaged switches with a fully flat network. The replacement job turned into a topology redesign: Subnet Works replaced the core and access layer, segmented traffic into VLANs per department, configured RSTP with deliberate root bridge placement to prevent topology changes from causing broadcast storms, and documented the final design.

EtherChannel and performance fix. An office with a server room was seeing intermittent 10-second network freezes several times a day. The cause was STP topology changes on an uplink that had been misconfigured without EtherChannel, causing brief loops each time a port bounced. Subnet Works configured LACP-based EtherChannel on the affected uplinks, adjusted PortFast and BPDU Guard on access ports, and the freezes stopped.