De : <vpp-dev@lists.fd.io> au nom de raju <rajugris...@gmail.com>
Date : vendredi 14 décembre 2018 à 14:58
À : vpp-dev <vpp-dev@lists.fd.io>
Objet : [vpp-dev] Feature arc and ordering graph nodes in an existing feature
arc.
Hi
I am trying to add a feature (say 'my_node') to ip4_unicast arc.
Goal is just like ip4_gtpu_bypass to by pass the IP stack and process packets
that are of my interest and if packets received are of not my interest give it
back to the ip layer.
At the same time I am trying to use ip4 reassembly on the interface using CLI.
(vppctl set interface reassembly GigabitEthernet13/0/0 on).
So expected graph
For packets of my interest :
dpdk-input --> ip4-input --> ip4-reassembly-feature --> my_node -->my_next_node
....
Packets that are of not my interest :
dpdk-input --> ip4-input --> ip4-reassembly-feature --> my_node --> ip4_lookup
--> ....
Q1. How are the feature nodes ordered in an arc ?
I tried to order these two feature my-node and ip4-reassembly-feature using
.runs_after like below and was able to get ip4-reassembly-feature before
my-node. And with out using .runs_after, the order was other way. (my-node -->
ip4-reassembly-feature).
VNET_FEATURE_INIT (my_node, static) = {
.arc_name = "ip4-unicast",
.node_name = "my_node",
[nr]
.runs_before = VNET_FEATURES ("ip4-lookup"), <<<<<< this you don’t need,
since ip4-lookup is always last
.runs_after = VNET_FEATURES ("ip4-reassembly-feature"),
};
Is this correct way of doing?
[nr] yes
Does the order of feature nodes in an arc depend on the order of enabling these
using the function 'vnet_feature_enable_disable' ?
[nr] no. only runs_before and runs_after are used to determine ordering.
Q2.
With the above code, I could get my intent working with normal packets of my
interest.
But for packets that are of not my interest I am not able to route them back to
ip4-lookup, instead packets come to my-next-node that succeeds my-node. I use
the function 'vnet_feature_next' to get the next feature in the arc by default .
that meaning to say
For packets of my interest next = my_next_node
and for packets that are not of my interest next is taken from
vnet_feature_next(vnet_buffer(b0)->sw_if_index[VLIB_RX], &next, b0);
have you defined my_next_node as an arc out of my_node, e.g.;
VLIB_REGISTER_NODE (my_node) = {
.name = "my-node",
.vector_size = sizeof (u32),
.format_trace = format_ip4_rewrite_trace,
.n_next_nodes = 1,
.next_nodes = {
[0] = "my-next-node",
},
};
/Neale
Sorry for the long writings.
Please advice.
Thanks
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