What is load sharing and why to use it? Load balancing with BGP is not possible in a multihomed environment with two ISPs. BGP selects only the single best path to a destination among the BGP paths that are learned from different ASs, which makes load balancing impossible. However, load Read more…
What is a Dynamic Multipoint VPN and why to use it? DMVPN provides the capability for creating a dynamic-mesh VPN network without having to pre-configure (static) all possible tunnel end-point peers, including IPsec (Internet Protocol Security) and ISAKMP (Internet Security Association and Key Management Protocol) peers. DMVPN is initially configured Read more…
What is a Layer 2 MPLS VPN and why to use it? Layer 2 VPNs are a type of Virtual Private Network (VPN) that uses MPLS labels to transport data. The communication occurs between routers that are known as Provider Edge routers (PEs), as they sit on the edge of Read more…
What is a Site-to-site IPsec VPN and why to use it? A virtual private network (VPN) extends a private network across a public network, and enables users to send and receive data as if their computers were directly connected to the private network. A site-to-site VPN allows offices in multiple Read more…
What is a Layer 3 MPLS GRE VPN and why to use it? The MPLS VPN L3VPN over GRE feature provides a mechanism for tunneling Multiprotocol Label Switching (MPLS) packets over non-MPLS networks. This feature allows you to create a generic routing encapsulation (GRE) tunnel across a non-MPLS network. The Read more…
What is conditional advertisement and why to use it? Normally, routes are propagated regardless of the existence of a different path. The BGP conditional advertisement feature uses the non-exist-map and the advertise-map keywords of the neighbor advertise-map command in order to track routes by the route prefix. If a route Read more…
What is inter-vlan routing and why to use it? Inter-vlan routing is defined as a process of forwarding network traffic from one vlan to another vlan using a router or layer 3 device. To facilitate inter-vlan routing a router must be connected to the switching infrastructure or the switch must Read more…
What is EIGRP load balancing and why to use it? Load balancing is a standard functionality of the Cisco IOS router software, and is available across all router platforms. It is inherent to the forwarding process in the router and is automatically activated if the routing table has multiple paths Read more…
What are VRF import/export maps and why to use it? VRFs are an excellent tool for maintaining segregated routing topologies for separate customers or services. However, what if you needed to export only a subset of routes within a VRF? Inter-VRF routing using route targets along with BGP are the Read more…
What is route filtering and why to use it? In the context of network routing, route filtering is the process by which certain routes are not considered for inclusion in the local route database, or not advertised to one’s neighbours. Route filtering is particularly important for use on large networks Read more…