Re: [mpls-linux-general] VRF for Linux

[James R. L. <jl...@mi...>]

On Thu, Sep 27, 2001 at 11:30:43AM -0500, Nick Eggleston wrote:
> As part of Cisco's MPLS implementation, they introduced a feature called
> VPN Routing/Forwarding (or Virtual Route Forwarding) referred to as VRFs
> [or maybe this is an RFC definition].
> 
> What work is being done for Linux to support this concept?
> In particular, making sure that ARP caches and FIBs can be VRFed.

Linux has the notion of multiple routing tables.  The table identifier can
be used as part of a route lookup.  Once a route has been choosen and
a next hop it determined, it will use the neighbor cache to to find
the next hop on that outgoing interface.

Currently, there is not the notion of an interface belonging to a table AFAIK.
Due to the way the arp cache works I do not think that you would need
an arp cache per table.

In addition I don't think there is a way for a socket to say which table
it wants to send it's packet to for a route lookup nor does it have a way
to limit which incoming interfaces can connect to a listening socket.

> In addition, is the VRF-aware versions of gated or zebra?

I do not believe so.

The details of how to add his support to linux are very intriging.
I wonder if anyone is working on this type of support yet ... maybe I should
start a VRF for Linux project ;-)

Jim

> 
> How about VRF-tagging of sockets or processes, to perform the same
> functions as the cisco commands:
> 
> telnet x.x.x.x /vrf name
> ping vrf name x.x.x.x
> traceroute vrf name x.x.x.x
> 
> Per-VRF nat, filtering, etc??
> 
> Can anyone help?
> 
> Thanks!
> 
> --Nick
> 
> ---
> 
> 
> VRF- Virtual Route Forwarding. Initially, a router has only one global
> default routing/forwarding table. VRFs can be viewed as multiple disjoined
> routing/forwarding tables, where the routes of a user have no correlation
> with the routes of another user.
> Source: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122limit/122x/122dx/122dx1/dd_vrfaa.htm
> 
> 
> A VRF defines the VPN membership of a customer site attached to a PE
> router. A VRF consists of an IP routing table, a derived Cisco Express
> Forwarding (CEF) table, a set of interfaces that use the forwarding table,
> and a set of rules and routing protocol parameters that control the
> information that is included into the routing table
> Source: http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t5/vpn.htm
> 
> 
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-- 
James R. Leu