Overlay Transport Virtualization is the technology that you may encounter, if you are going to span your Data Center across different geographical location with full retaining of layer 2 information. It literally enables you connectivity between 2 servers within the same Vlan that are placed far away of each other. 



In the course of time the old-fashioned model od Data Center became inefficient especially when requirements regarding the traffic from North-South (client-server) have changed itself to East-West (server-server) and demanding applications started to be “hungry” for more than Gigabit links bundled via Portchannel. Also the better redundancy with non blocking links has started to be desirable.  All this problems resolved   new Spine-Leaf architecture and Application Centric Infrastructure as an easing in management.

The difference between phase 2 and 3 regarding DMVPN is slight at a first glance. In this article we will find out how to properly configure Phase 3, especially we focus on  NHRP protocol and its role. At the end we will establish full reachability between 2 spokes with utilization of EIGRP.

Sham Link feature is necessary if we want to deploy backdoor link between 2 OSPFs domains belong to the same area but split by MPLS. The issue that we will come across is a result that backdoor link will have priority over the MPLS.

We may come across on interesting issue if we get the same prefix from external BGP AS and directly via OSPF process. It may happen if we want to have another link to the destination but not neccesarily via another eBGP link. The problem that we will definetely come across on is just  another variation of suboptimal routing. 

MPLS works based on underlying IGP protocol. It may be OSPF or IS-IS, but whatever we choose, we are still dependant to IGP path calculation. Of course we may manipulate the cost of path and this way provide traffic enginering, but MPLS has its own mechanism.

Simple Modular Policy Framework and application inspection enable us for example inspection of FTP connection. When we use passive mode we need beside opened  port 21 as a control channel also any random port as a data channel. Thanks to MPF and  traffic inspection ASA knows what is the number of this random port and entire connection is enable. Great!

bgpsmalllIn this artcile we will focus on fundamental and crucial features of BGP neighborhood establishing and routes injecting into BGP processes, we also break BGP table down  for better understanding.

Cisco recently has made a small step to improve ASA  and has implemented logical tunnels, what means we got route based VPN! Really? Did we?  Not so fast. Yes, we got route based VPN but still we have to add  routes manually.

Thanks to this lab with simple topology we will study, how to configure iSCSI protocol in Linux and SAN environment. We gonna pass through iSCSI, Network File System and Server Message Block (SMB) also known as CIFS and at the end of the day we will be able to use  resources in SAN connected to the file server by iSCSI from Linux and Windows hosts.