Dennis Rardin
Oak Park,IL
Summary
Results-driven Network Engineer with 25 years of expertise designing, deploying and maintaining LAN, WAN and firewall infrastructure. Dedicated technology professional with strong track record in all phases of the network life cycle. Keen interest in improving efficiency with scripting tools. Exemplary planning, project management and communication skills.
Overview
27
27
years of professional experience
Work History
Senior Network Engineer
Heartland Business Systems (HBS)
10.2023 - 06.2025
- Company Overview: HBS is a VAR and professional services organization with clients primarily in the education and government sectors.
- Design and implementation of Palo Alto and Fortinet firewalls, Cisco FTD/FMC, Cisco Catalyst 9300 and Nexus, and similar platforms.
- Improved margin of major switch deployment project by supervising group of lower level engineers to complete the project.
- Laid off due to low volume of professional services work in the Chicago region.
Independent Consultant
Self Employed Services
06.2023 - 10.2023
- Senior network resource on three security penetration remediation projects in summer and fall of 2023.
Network Implementation Engineer
Pico Services
01.2016 - 03.2023
- Company Overview: Pico is a managed service provider in the financial trading space, providing live market data and order entry to clients such as J.P. Morgan, Goldman Sachs, and Wells Fargo, and numerous other clients.
- Senior and go-to engineer on team of 6-8 engineers.
- Identified and initiated projects to correct potentially service-interrupting design and configuration flaws.
- Designed automated process to provision client connectivity to over 200 different exchange products.
- Mentored new and more junior engineers.
- Designed and implemented separation of corporate and production environments for SOC2 compliance.
- Only engineer assigned to redesign of NYSE connectivity. Leveraged automation to touch over 300 devices during each of 3 change windows with less than 1% error rate.
- Custom scripting to retrieve configuration information, and generate custom reports on all routes exchanged with external BGP peers, interface and port status for every available physical and logical interface in the network of over 2500 network devices, all ACL’s, IPAM information, etc.
- Network grew tenfold, from North America to a global infrastructure of over 2000 network devices.
- Connectivity to AWS; Fortinet load balancing.
- Routing protocols: BGP, MPLS, OSPF (before it was phased out), PIM sparse, a bit of PIM dense.
- Arista 7150 and 7280, 7130 for Layer 1 switching, Cisco Nexus 3500, Cisco and Fortinet firewalls.
Senior Security Engineer (contractor)
United Airlines
06.2015 - 12.2015
- Custom scripting using Firemon traffic analysis reporting and Infoblox IP address data.
- Identify application traffic (“port clusters”) within and to multiple data centers.
- Recommend rules and policies to be built on application requirements instead of large IP blocks.
Senior Firewall Engineer (contractor)
Halock Security Labs
07.2014 - 06.2015
- Company Overview: Halock is a boutique provider of high-end network and data security services.
- Lead firewall engineer on a 7-figure value perimeter security evaluation and hardening project.
- Did majority of work to analyze risk, and recommend remediation, for >75K firewall rules from over 200 devices/contexts.
- Devices include Cisco ASA, Checkpoint, Juniper SRX firewalls.
- Significant exposure to Algosec firewall policy tuner.
- Created TCL scripts to automate analysis of policy and object data from Algosec, and from raw device configuration files, to evaluate risk according to specific customer criteria.
- Recommendations and change scripts provided for remediating ~15,000 high-risk firewall rules.
- Deeply involved in client interactions to expedite change management processes and integrate additional contractor resources into the effort.
Senior Network Engineer (contractor)
Schawk
01.2010 - 06.2014
- Company Overview: Schawk, now the SGK division of Matthews, Inc., designs packaging and other advertising media for many of the world's most familiar brands.
- Primary much of the time the only, network engineer in 55-site international WAN.
- Designed and implemented network for 4 virtualized data centers (Chicago, New York, London, and Singapore) using 10 Gigabit WAN connectivity, FCoE and 10-Gig Ethernet on Cisco Nexus 5000 and Catalyst 4900 platforms, Palo Alto and Juniper SRX firewalls.
- Designed multi-tiered DMZ’s to isolate core production servers from each other by function, and from application front ends.
- Recommended and deployed open source network management. Provided Network KPI’s (uptime, utilization, latency, packet loss, interface errors), up/down, configuration backup.
- Designed and deployed world-wide “WLAN 2” with centralized Cisco WLC’s across over 30 sites.
- Managed Cisco support contract, reduced cost by 40%.
Senior Network Engineer (contractor)
7ticks, LLC
02.2009 - 09.2009
- Company Overview: 7ticks provided very low latency real-time trading connectivity to Chicago, New York, London, and Frankfurt, for over 30 clients. The firm was eventually purchased by the ICE.
- Short term contract.
- Created configuration template for adding new customers to the complex MPLS VRF infrastructure; reduced error rate when creating network configurations for new clients.
- Designed standardized inter-VRF MPLS routing deployment to ease configuration of client connectivity.
- Created highly automated, redundant Linux network management server with password repository, configuration backups, automated QA of major network scripts.
Senior Network Engineer (contractor)
Newedge Financial
01.2008 - 01.2009
- Company Overview: Newedge is a very large international brokerage firm active on all the world’s exchanges.
- Migrated 50 business critical client trading circuits from obsolete data center in 4 months.
- Newedge is a very large international brokerage firm active on all the world’s exchanges.
- Short term contract.
Senior Network Engineer
PAX Division of Merrill Lynch
01.2005 - 01.2008
- Company Overview: PAX cleared over 1/3 of the CBOE's volume. The low-latency network provided customer access to New York, Chicago, Philadelphia, and San Francisco stock, options and commodity exchanges.
- Design, implementation, and troubleshooting of about 500 Cisco devices in a highly redundant, highly available, revenue-critical financial trading network.
Sr. Network Engineer
Presentation Services/PSAV/AVSC
02.2003 - 01.2005
- Company Overview: PSAV is a vendor of choice for convention and event planning at over 600 premier hotels, convention centers, and trade shows throughout the US.
- Only design and implementation engineer in 600-site VPN based WAN.
- Design and implementation of PIX firewalls at multiple locations.
- Trained help desk personnel to do Tier I troubleshooting of network outages.
Sr. Network Engineer (contractor)
Citadel Investment Group
02.2002 - 01.2003
- Support, configuration and design work in highly advanced, fully redundant worldwide financial trading network which supported millions of transactions daily.
- In-depth use of Cisco Catalyst 6500 Layer 3 switches in multilayer, multicast environment.
Contractor
Pactiv
07.2001 - 01.2002
- Company Overview: Pactiv produces Hefty bags and many other consumer packaging products; the network supports Pactiv's North American operations in over 40 locations.
- Created detailed plan to build an IP fault detection and event correlation system superior to then-current implementation of HP OpenView and Micromuse Netcool.
Shift Supervisor
Comdisco Network Operations Center
11.1998 - 06.2001
- Company Overview: The Comdisco NOC managed 40 client WAN’s consisting of approximately 6000 Cisco devices. The business unit has changed hands and evolved into Cisco's managed network services offering.
- Tier 2 WAN technical support; responsible for resolution of all in-depth technical issues.
- Received highest job performance rating given by NOC manager in July 2000.
- Trained new employees and delegated daily tasks and responsibilities.
Education
Master of Divinity - Theology
Wisconsin Lutheran Seminary
Mequon, WisconsinBachelor of Arts - Classical Studies
Martin Luther College
New Ulm, MNSkills
- 25 years experience in the route/switch/firewall space Design/deploy/operate
- Arista, Cisco (Catalyst and Nexus) switches
- Palo Alto, Fortinet, and Cisco FMC/FTD firewalls
- 12 years experience in complex financial trading networks, including exchange order entry, multicast routing and IGMP, robust fault tolerance, low latency including layer 1 switching
Accomplishments
- 25 years of experience in Arista and Cisco based network design, deployment, support. Catalyst and NXOS Cisco switches and routers, also Arista and some Fortinet.
- 12 years experience in complex financial trading networks, including exchange order entry, multicast routing and IGMP, robust fault tolerance, low latency including layer 1 switching.
- Routing protocols: BGP and (light) MPLS, OSPF, PIM, EIGRP.
- Ethernet switching protocols, including VLAN’s, 802.1q trunking, LACP link aggregation and port channels, STP/RSTP, DWDM. LAN including VRRP/HSRP, DHCP, NAT, LLDP/CDP. Spine Leaf architecture.
- In-depth protocol analysis to identify network faults and root cause of latency issues using Wireshark.
- Network Security: Firewalls including Cisco ASA, Fortinet, Juniper, Palo Alto. LAN-to-LAN and Client-based IPSec VPN design and implementation.
- Network Management using custom scripting and a variety of Open Source and proprietary tools.
- Linux administration focused on network management, including TCL/Expect and Bash scripting for configuration backups, reports on status of all network ports/interfaces, IPAM data, automated change deployment.
- AAA using Cisco ISE (formerly ACS), open source TACACS.
Timeline
Senior Network Engineer
Heartland Business Systems (HBS)
10.2023 - 06.2025
Independent Consultant
Self Employed Services
06.2023 - 10.2023
Network Implementation Engineer
Pico Services
01.2016 - 03.2023
Senior Security Engineer (contractor)
United Airlines
06.2015 - 12.2015
Senior Firewall Engineer (contractor)
Halock Security Labs
07.2014 - 06.2015
Senior Network Engineer (contractor)
Schawk
01.2010 - 06.2014
Senior Network Engineer (contractor)
7ticks, LLC
02.2009 - 09.2009
Senior Network Engineer (contractor)
Newedge Financial
01.2008 - 01.2009
Senior Network Engineer
PAX Division of Merrill Lynch
01.2005 - 01.2008
Sr. Network Engineer
Presentation Services/PSAV/AVSC
02.2003 - 01.2005
Sr. Network Engineer (contractor)
Citadel Investment Group
02.2002 - 01.2003
Contractor
Pactiv
07.2001 - 01.2002
Shift Supervisor
Comdisco Network Operations Center
11.1998 - 06.2001
Master of Divinity - Theology
Wisconsin Lutheran Seminary
Bachelor of Arts - Classical Studies
Martin Luther College
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