Re: [PATCH v3 00/14] add lookup fib nodes in graph library

[Nitin Saxena <nsaxena16@gmail.com>]

Hi Morten,

Let me take a stab regarding the VRF question.
Please find answers inline

Thanks,
Nitin

On Mon, Jun 2, 2025 at 2:12 PM Morten Brørup <mb@smartsharesystems.com> wrote:
>
> +TO: Robin Jarry, might have relevant feedback for such a node
>
> > From: Ankur Dwivedi [mailto:adwivedi@marvell.com]
> > Sent: Monday, 2 June 2025 08.36
> >
> > This patch series adds two inbuilt nodes ip4_lookup_fib and
> > ip6_lookup_fib in graph library. These nodes uses the existing
> > Forwarding Information Base (FIB) library to create FIB, to do
> > route addition and route lookup.
> >
> > Two new commands (for ipv4 and ipv6) for providing the lookup mode
> > is added in the dpdk-graph application. fib or lpm can be given as
> > lookup mode. If these new lookup mode commands are not given, the
> > dpdk-graph uses lpm (Longest Prefix Match) or lpm6 by default.
> > If fib is given as lookup mode then the ip4_lookup_fib or
> > ip6_lookup_fib
> > nodes are used by the application.
>
> @Ankur, @Vladimir, @Jerin,
>
> A couple of high level questions...
>
> 1. Thread safety:
> I'm not familiar with the thread safety models of the FIB and Graph libraries.
> Is the FIB library thread safe, so one thread can invoke the FIB modify operation while other threads invoke the FIB lookup operation?
> If it isn't, how does the Graph library make its use of the FIB library thread safe?
>

Just a nit-pick here, there are two libraries used by rte_graph applications
- Graph library (lib/graph/*)
- Node library (lib/node/*)

Questions here are pertaining to "Node library" and not to "Graph library"

> 2. VRF support:
> This looks like a global route table for the entire graph.
Correct.

> Shouldn't there be a route table per FIB node?
Yes when VRF support is added in library, one FIB would support on route table

> Or how are VRFs supported by the Graph library?
> Or is there no requirement to support VRFs in the Graph library?
>
Currently the node library(instead of Graph library) does not support
VRF. There is an intention to add it in lib/node/ip[4|6]-lookup nodes
IMO, @Vladimir can correct me, even FIB support for multiple VRF is
unoptimized because rte_fib_lookup_bulk() function takes single fib
pointer instead of multiple fib pointers
For adding VRF support in ip[4|6]-lookup nodes ideally we would like to have

rte_fib_lookup_bulk(struct rte_fib *fib, uint32_t *ips, uint64_t
next_hops, int n); (OR different new API)

taking an array of fib pointers (or fib index) corresponding to each
nth packet. It should also avoid fib->lookup() callback for every
packet.
We can also add this API as part of "Node library" but we need "static
inline" version of fib->lookup() in rte_fib header file

> -Morten
>