Achieving Optimal Redundancy in a Small Business Network

Redundancy is a highly desirable element of the network, but sometimes it is not so easy to find the optimal level of redundancy that will ensure satisfactory performance of the entire network and at the same time being affordable and easy to implement. Redundancy in the network can be performed in several ways, which can be compatible and co-exist in the network, but can also be mutually exclusive. Although at first it seems that the redundancy depends only on the size of the network, this is not entirely true. One of the main factors to take into account is the complexity of the network and the importance of services and applications that serve the company’s business and its customers. Network redundancy can be achieved in various ways. STP for example is the most basic mechanism but has several major drawbacks like underutilization of some links. Also link aggregation mechanisms could be used, which usually means investing in optical transcievers which implies a certain cost, and if one is using switch stacking it will further increase costs. For gateway redundancy one of FHRP protocols can be used which is certainly desirable. This paper will describe the redundancy in Small and Medium networks with few hundred clients and one way how to ensure redundancy by using various mechanisms such as the STP protocol, link aggregation, implementation of FHRP for gateway redundancy and using stackable switches with short analysis of recovery times for these mechanisms

Connecting Customer Locations Using Different Service Provider MPLS Networks

MPLS (Multi Protocol Label Switching) technology is de facto standard in service provider environments and most companies are connected over service provider MPLS infrastructure. Sometimes it happens that one company from a small country such as Croatia merge with another company in a small country like Slovenia. Both companies have their own network infrastructure that is connected through service providers in their respective country, but since the two companies are now one administrative domain their networks should reflect this and connect into one bigger network in order for this network to become more efficient and to better support business goals. There are simple and common solutions such as S2S VPN, but in this case it would not be long-term and optimal solution especially if there is traffic like multicast, VoIP or various datacenter traffic. The direction in which we should go is to connect the two companies into a single organization using one of the mechanisms for connecting service providers also known as carrier supporting carrier. In this paper we will describe advantages and disadvantages using carrier supporting carrier options A and B. Once two companies are connected in this manner, it is much easier to manage traffic and to implement QOS mechanisms

Alternative to using VRRP for Mutual Next-Hop Redundancy

In a situation where customers end locations and its central infrastructure servers are connected over service provider MPLS (Multi Protocol Label Switching) network infrastructure, each customer site, including the central one is one MPLS connection. To ensure redundancy for the central location where the customer servers are located, most companies use two MPLS connections so that if one fails other will take over the traffic. For various reasons, some companies have not implemented a dynamic routing protocol, and all of their routing decisions are based on static routes, which is not a good solution. Such companies for purposes of routing redundancy choose to use FHRP (First Hop Redundancy Protocols) protocols in combination with interface tracking in both directions to ensure failover when needed. This combination is used to ensure redundant two-way communication that is resistant to one link or one device failure. In this paper, we describe the method of implementing VRRP (Virtual Router Redundancy Protocol) protocol in combination with interface tracking mechanism to ensure the availability of key elements of customer networks and present shortcomings of this model on the availability of customer infrastructure. Also, we will compare this solution with the conventional solution using a dynamic routing protocol

Smjernice za farmakološko liječenje epilepsije

SAŽETAK Međunarodne smjernice za farmakološko liječenje epilepsija općenite su, sveobuhvatne i ne prepoznaju lokalne specifičnosti poput ekonomskih i tehničkih mogućnosti u pojedinim državama, dostupnosti pojedinih antiepileptika ili drugih metoda liječenja i slično. Stoga se nameće potreba izrade nacionalnih smjernica, čiji su zapravo temelj međunarodne smjernice Internacionalne lige protiv epilepsije. Hrvatske smjernice za farmakološko liječenje epilepsija plod su suradnje svih relevantnih stručnih društava i referentnih centara u RH, na čelu s Hrvatskom ligom protiv epilepsije te Hrvatskim neurološkim društvom i Hrvatskim društvom za dječju neurologiju Hrvatskoga liječničkog zbora, a odražavaju aktualne socioekonomske i regulatorne specifičnosti u našoj zemlji, najnovije spoznaje farmakoloških profila i učinkovitosti pojedinih antiepileptika kao i ekspertna mišljenja. Antiepileptička terapija se uvodi nakon postavljanja dijagnoze epilepsije, stoga profilaktička primjena nije opravdana. Nakon postavljanja dijagnoze potrebno je bolesnika informirati o prognozi bolesti, mogućnostima liječenja i samopomoći, životnim ograničenjima te mogućim neželjenim događajima. Ciljevi farmakoterapije epilepsija su potpuna kontrola napada uz izbjegavanje nuspojava te održavanje ili poboljšanje kvalitete života. Zlatni standard liječenja je monoterapija odnosno primjena adekvatnog antiepileptika u adekvatnoj dozi. Izbor i titracija lijeka su individualni, a temelje se na smjernicama za liječenje pojedinih vrsta napada, karakteristikama bolesnika i regulatorno specifičnim čimbenicima. Nakon neuspjeha inicijalne monoterapije, potrebna je reevalucija anamnestičkih i dijagnostičkih podataka te potom postupna i spora zamjena antiepileptika. Racionalna politerapija podrazumijeva kombinaciju dvaju antiepileptika različitih mehanizama djelovanja, prvog ili eventualno drugog izbora za postavljenju dijagnozu, niskoga interakcijskog potencijala, različitog profila nuspojava i sinergističkog ili aditivnog djelovanja. Zamjena generičkih ili originalnog i generičkog oblika lijeka nije preporučljiva, a poglavito nakon postizanja remisije ili prilikom uzimanja visokih doza lijeka. Ukidanje antiepileptičke terapije treba biti postupno i sporo, u slučaju politerapije jedan po jedan lijek, a u donošenju odluke o ukidanju, kao i o uvođenju antiepileptika, mora biti uključen bolesnik i njegova obitelj