NHRP GRE Multipoint

Hi I would like to know the fuctions which are put in use for the Point-to-Point Generic Routing Encapsulation (GRE) Tunnels as well as the NHRP?

[Kiran Chandar]

The prominence of Virtual Private Network (VPN) arrangements has risen extensively in the course of the most recent quite a while. The equipment is getting to a point where VPN speeding up is financially savvy and ready to be performed on a solitary gadget.

Point-to-Point Generic Routing Encapsulation (GRE) Tunnels

The customary usage of a GRE burrow included the design of a point-to-point burrow going between two destinations. This kind of design functions admirably when this is the conduct and there are a set number of passages that should be arranged. Nonetheless, if there are an expansive number of talked destinations, the arrangement of the center point switch and the quantity of free IP address ranges (one for every passage) could get exorbitant rather rapidly


Figure 1 on Point-to-Point GRE



Dynamic (Hub Side) Multipoint Generic Routing Encapsulation (mGRE) Tunnels

The following sort of GRE arrangement utilizes mGRE at the center point site (R1 for this situation) and typical point-to-point GRE design at the spokes. There are two primary ways this can be arranged yet before hopping into this a short examination of the Next Hop Resolution Protocol (NHRP) is required. NHRP is utilized likewise to the Address Resolution Protocol (ARP) on Ethernet, it gives the capacity to delineate passage IP address with a consistent (Non-Broadcast Multi-Access (NBMA)) IP address; this permits mGRE to have powerfully set up passages without having to unequivocally design a mapping section between every potential next-jump destination. This is obviously a distortion however for the reasons of this article this measure of data ought to elucidate the following part of this segment.

As expressed above there are two distinct approaches to arrange mGRE on the center point and leave a "typical" GRE setup on the spokes; the primary uses static NHRP mapping explanations on the center switch and the second uses dynamic NHRP mapping on the center switch.

A sample of the setup required utilizing static NHRP mapping explanations; the figure likewise demonstrates some extra NHRP arrangement articulations that would be required if utilizing EIGRP (or any directing convention requiring multicast).


Figure 2 – Dynamic (Hub Side) mGRE using static NHRP statements