From Field Experience to
Enterprise IT Management.

Doğan Şahin has more than 35 years of field and engineering experience in information technologies, enterprise network infrastructures and service-provider-level IP backbones.

Throughout his career, in addition to enterprise IT systems, he has worked on the planning, commissioning, operation, optimization and fault-management processes of Core / Backbone IP networks in ISP (Internet Service Provider) environments.

His technical areas of expertise include high-capacity Core and Aggregation network architectures, BGP-based Internet routing policies, IGP protocols such as OSPF and IS-IS, MPLS backbone structures, VRF, L2VPN and L3VPN services, and IPv4 / IPv6 addressing and routing architectures.

On the BGP side, he has worked with eBGP and iBGP topologies, route-policy design, prefix filtering, route-map / policy mechanisms, Local Preference, MED, AS-Path, BGP Community, route aggregation and traffic-routing policies. He has experience managing traffic carried through upstream providers, transit operators, peering connections and Internet Exchange Points according to performance, capacity and redundancy criteria.

In Core network infrastructures, he has worked on high availability, active/active and active/passive redundancy scenarios, alternative traffic paths, failure-domain design and network architectures intended to eliminate single points of failure.

In MPLS-based service-provider networks, he has technical experience with Label Switching concepts, MPLS forwarding, VRF separation, Layer 2 and Layer 3 VPN services, isolation of customer networks and secure service transport across the operator backbone.

Within IP traffic engineering, he has carried out work on balancing Internet traffic across different upstream connections and backbone routes, reducing latency and packet loss, analyzing routing asymmetry and optimizing capacity utilization.

In network troubleshooting processes, he has taken part in the analysis and resolution of BGP session problems, route-propagation errors, routing loops, asymmetric routing, packet loss, latency, jitter, MTU problems, interface errors, CRC errors, high traffic utilization, link saturation and backbone-level reachability problems.

On the network-security side, he has experience with ACLs, prefix filtering, anti-spoofing, BGP-based blackhole routing, RTBH, traffic filtering and service-provider-level traffic-control mechanisms that can be used against DDoS attacks.

In IPv4 and IPv6 networks, he has worked on the design and operation of addressing and routing infrastructures, including IP planning, subnetting, address allocation, route summarization, dual-stack architectures and IPv6 transition processes.

Monitoring traffic capacity in backbone and access networks, analyzing growth trends and planning capacity upgrades have also been among his responsibilities. By evaluating port, uplink, backbone and transit utilization rates, he has carried out work aimed at forecasting future network-capacity requirements.

In network operations, he has worked with NOC, systems, field and security teams on root-cause analysis of complex incidents, preparation of change plans, execution of maintenance activities and controlled implementation of critical network changes.

Documenting network topologies, IP plans, routing policies, connection diagrams and change records, as well as establishing operational standards and developing sustainable network-management processes, are also among his areas of expertise.

Today, Doğan Şahin brings his service-provider-level Core / Backbone network experience into technical consulting and solution-architecture processes for enterprise customers at Doz Teknoloji in the areas listed below.

The core objective of this approach is not merely to install products or devices, but to analyze organizations' existing infrastructure and design scalable, secure, redundant, manageable and long-term sustainable IT architectures.