Development and support of network infrastructure (core + aggregation), starting from BGP uplinks (including the core on iBGP+MPLS based on Cisco) and ending with backbone aggregating 10G switches in the ring on MRPP and ERPS (QTech switches).Supported the network part of telephony (PSTN + SIP) on CISCO equipment. Early used to manage communication between cities via Frame Relay with separation between telephone and IP traffic over different time slots of single E1 link. Gained experience with Sprinter equipment that packs PRI streams into packets and transmits over an IP network with duplication.The Zabbix monitoring system was implemented and maintained with the maximum possible (as of version 6.2) automation: dynamically connected C++ modules, PHP and PERL scripts for getting monitored data where it is impossible to get directly, internal JavaScript scripts, alert notifications via Telegram.Created a system for receiving satellite TV channels on a scale from aligning parabolic antennas to distributing them over the network via Multicast, setting up streamers on Debian.Supported gateway servers that acts between the subscriber network, technical network and the office network with the possibility of remote connection via OpenVPN. Supported a storage server with backups of both virtual machines and hardware configuration, the presence and completeness of which was controlled by Zabbix monitoring.Participated in the implementation of a support ang managers' call center based on FreePBX.Wrote many different scripts in PERL, PHP (both CLI and WEB) and C++ daemons to automate various production processes.

Supervised the technical aspects of creating an internet operator from scratch:Built a network based on Cisco routers (BGP, BRAS, RADIUS roles) and QTech switches (DHCP Option82)Implemented a virtualization cluster of two hypervisors (DRBD + OCFS2 + XEN) and everything the operator should have: two DNS servers with AXFR and reverse zones delegated from RIPE NCC, mail server, Billing system, monitoring based on Zabbix, Web server, secure gateway and other related services.Implemented my own product thich automating and accelerating the diagnosis of subscriber problems and including a ticket system, integrated with Telegram messenger for alert notifications. The product was redesigned for the current version of billing system and for the current scheme of work in the operator. I also rewrote its engine with optimization included mobile devices. Written in PHP8 + MySQL using protocols such as SNMP, Telnet and SSH.

Maintained the operability of the access network of subscribers connected using FTTB and ADSL technologies;Setting up the interaction of telecom operators via BGP, maintaining a connection to a regional peering operator;Had a configuring experience in DHCP Option 82, DNS (primary and backup servers with reverse zones registered with RIPE NCC), OSPF between communication nodes, MySQL, Apache, PHP, Zabbix, SNMP, LLDP, ACL. Under responsibility were ~15 servers of varying complexity on several Linux distributions (file access via Samba, high-load MySQL DBMS, traffic shaping (BRAS) servers with SFP cards, etc.), Cisco 6500 routers, Cisco SCE, D-Link 12xx, 30xx, 3200-xx series switches, Cisco 29xx. An automated complex was developed and implemented myself from scratch (initially as an add-on to the billing system) for diagnosing subscriber problems. The complex has integration with both: a call center based on Asterisk (automatic called number identification and comparison with the subscriber data) and switches via SNMP in terms of diagnosing a problem up to interpreting the test results of the last mile cable. There is also a ticket system and applications for connection of customers and ample opportunities for managing them. There is an integration with an SMS gateway to notify subscribers about a near-zero balance, diagnostics of the switches themselves and a quick selection of their important "vital indicators" for further analysis by engineers. The system was designed to minimize the time required to obtain the necessary information, with the corresponding maximum optimization of the database.