VRF limit on vrf-lite

[akin_lopez]

Hello guys. i am thinking of using vrf-lite on a CE for IP seperation but i want to know the limit of the number of VRF allowed when using vrf-lite (i am using a 7206 as CE)

[pkhatri]

Hi,

I don't believe there is a hard limit as such. You can create as many VRFs as you want but you will eventually be limited by the number of interfaces you have on the router + router load.

Hope that helps - pls rate the post if it does.

Paresh

[akin_lopez]

hello,

I saw on cisco site that the 4500 can only have one global table and 64 vrf (max)

http://www.cisco.com/en/US/products/hw/switches/ps4324/products_configuration_guide_chapter09186a00801cddd9.html#1045269

with this, it is likely the 7206 too has limitations like this and not actually cpu or interface limitations.

what do you think?

[pkhatri]

Hi,

We've got 7206VXR PE routers in our MPLS network with a lot more than 100 VRFs on each of them. While we use them for MPLS VPNs, the VRF construct is no different to using them for VRF-Lite.

Hope that helps - pls rate the post if it does.

Paresh

[jayjorda]

The Catalyst 4500 has a limit of 64 vrfs due to the architecture of the box. The Catalyst 6500/Cisco 7600 with a Supervisor 720-3B/3BXL has a maximum of 1024 vrf (actually 1023 with the global table) due to architecture of that supervisor.

The 7200 has a recommended maximum of 1000 vrfs. The real limiting factor is the number of routes in each vrf though. The maximum recommended number of routes across all vrfs in the 7200 is 150,000.

Jay

[akin_lopez]

Thnaks! so does that mean i will be able to go beyond 1000 vrfs if i don't have lots of routes in each vrf?

thanks

[jayjorda]

Theoritically yes, but you still will be constrained by how much memory you have in the router and the maximum number of interfaces (both physical and logical) or more accurately, IDB (interface descriptor blocks) supported by the IOS version. Different platforms and different IOS versions have different IDB limits. Every interface is allocated an IDB, either a hardware IDB (for phyical interfaces) or a software IDB (for logical interfaces ie. subinterfaces).

IDBs consume memory as do routes, as do vrfs, as do different features you turn on.

Also, IDBs, once allocated, the memory remains allocated until the router is reloaded. That is why subinterfaces aren't completely removed from the router until a reload when you delete them from the config.)

Depending on the IOS version, you can use the "show idb" to see your IDB allocation on the box. Also, the following link talks about what IDBs are and limits per platform.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_tech_note09186a0080094322.shtml

Jay