virtualization path

[panarania3]

hello to you all and hope all of you doing well and safe, 

I have question about virtualization path in (ccnp) topic , 

1-vrf is used to make routers that enables multiple instances of a routing table but what is advantage of that instead of global routing table we have virtual routing table ?

2-GRe , is used to make data path virtualization between 2 device (point to point ) it is only support unicast ,

and we have gre over ipsec to make it secure also with ipsec only  support  unicast   , because ipsec support broadcast multicast ?

[Kasun Bandara · Accepted solution]

1. we are using VRF to isolate different routing tables from global route table to avoid overlapping same network ranges in same device. also it gives certain security features.

https://avinetworks.com/glossary/virtual-routing-and-forwarding-vrf/

2. GRE supports, unicast and multicast. GRE is not encrypted natively. so we use GRE over IPSEC to encrypt traffic and because GRE is OVER ipsec, it can pass multicast. IPSEC alone cannot pass multicast.

https://ipwithease.com/gre-over-ipsec-vs-ipsec-over-gre/

[MHM Cisco World]

why VRF ?
in MPLS L3VPN if the costumer run same subnet, how can we connect same subnet to provider router?
we need VRF to separate the routing table to make both costumer same subnet connect to one provider router.

for GRE can you more elaborate ?

[panarania3]

 my qre question is:  IPSEC  Can encapsulate unicast IP packets and Gre:Can encapsulate nearly any type of data

Gre over ipsec : Can encapsulation any kind of data securely ?

[MHM Cisco World]

and GRE over IPsec add more overhead to packet so instead we use IPsec IPV4.