Virtual router on a Cisco

Unanswered Question
Oct 14th, 2009

Hi,

I would like to know if there is the concept in the Cisco IOS of having on a router different virtual routers, with separate routing and forwarding tables.

My company is using a lot of Juniper devices because of this feature and I would like to be able to show them the Cisco alternative but I've been unable to find anything related to it.

I've seen the VRF-Lite but I believe this is for MPLS, and what I am looking for is just a virtual separation into several "systems" on the same CPE router.

Regards,

Paulo

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Giuseppe Larosa Thu, 10/15/2009 - 00:13

Hello Paulo,

VRF lite can be enough because provides separate routing and forwarding tables and doesn't need either support MPLS.

Actually VRF lite just provides segregation and it is handy to use with SVI (vlan L3 interfaces) or Vlan based subinterfaces.

What VRF lite misses is a separated management/vista you see the device as a whole box.

There are specific show commands VRF specific starting from

sh ip vrf

sh ip route vrf

You can run different routing protocols in each VRF.

but you telnet/SSH to the same ip address

see

http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/46sg/configuration/guide/vrf.html

in IOS XR is possible to create virtual routers and to assign linecards to each of them but this available only on the high end routers like GSR 12000 and CRS.

Hope to help

Giuseppe

pjhenriqs Thu, 10/15/2009 - 06:12

Thank you Giuseppe. I have tested this at a very high-level and it seems to be working fine.

Is there any limit on the amount of VRF's I can configure?

Giuseppe Larosa Thu, 10/15/2009 - 07:23

Hello Paulo,

thanks for your kind remarks

the limit of max VRFs is device dependent.

It is 1024 on a C6500/C7600 with sup720.

It is less on C4500 (supervisor model dependent I would say).

It should be of the order of 20-25 on C3750 or C2560 devices.

Hope to help

Giuseppe

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