Creating a VRF - does it create an actual new routing process?

[vv0bbLeS]

Hello all,

When I create a VRF on a router or L3 switch, am I creating just a separate routing table (like just a separate dictionary of routes), or am I creating an actual new routing process on the box ? So often in diagrams I will see VRF's represented with router icons, and the name does imply that a new separate routing process is created (Virtual Routing and Forwarding), but then I think about routers with 10-20 VRF's, and if that's scalable to have the router create 10-20 separate routing processes and have them all running concurrently? And perhaps this is Cisco secret sauce here, but any info is appreciated. So far I've been thinking of VRF's almost like separate tabs in an Excel spreadsheet (so one Excel engine (routing process) but with many worksheet tabs (VRF's)), but perhaps I need to start thinking of VRF's as actual virtual routers, like full-blown virtual routing processes that can accept punts/gleans, etc. ?

[Giuseppe Larosa · Accepted solution]

Hello @vv0bbLeS ,

each VRF has its own routing table, its own ARP table , its own IP daemon that mantains the per VRF routing table.

VRF can be seen as a logical virtual router.

However all VRFs share the same management plane they are not Firewall contexts in ASA or Nexus VDCs.

In IOS XR we can create logical systems that are the result of partitioning the hardware resources but in the case of IOS XR  each logical system will have its own management plane , control plane and so on.

Hope to help

Giuseppe

[MHM Cisco World]

It confuse 

Cisco called router Install in VM virtual router 

And also called vrf virtual router 

For me complete virtual router is case 1

And case 2 I like to called it separately layer 3 of router not complete virtual router. 

You see vrf have it rib and arp but don't have it l2 or L1 layers.

MHM

[Joseph W. Doherty]

A VRF is to L3 much like a VLAN is to L2.

"When I create a VRF on a router or L3 switch, am I creating just a separate routing table . . ."

No it's not just a routing table, you're creating a virtual L3 environment, but not a full blown virtual router.

BTW, "virtual router" is also used by Cisco when describing HSRP.  So, realized some terms have multiple shades of meaning.

[vv0bbLeS]

@Joseph W. Doherty  thank you! So kind of like @Giuseppe Larosa 's response, a VRF is a "sort-of" virtual router, in that it has its own routing/ARP table and IP daemon (i.e. virtual L3 environment as you said), but not a "full-blown" virtual router because it won't have its own control/management plane (so no separate route processor, etc.).