FIB2.0: Adjacency complete pull model (VPP-487)

Change the adjacency completion model to pull not push.

A complete adjacency has a rewirte string, an incomplete one does not. the re-write string for a peer comes either from a discovery protocol (i.e. ARP/ND) or can be directly derived from the link type (i.e. GRE tunnels). Which method it is, is interface type specific.
For each packet type sent on a link to a peer there is a corresponding adjacency. For example, if there is a peer 10.0.0.1 on Eth0 and we need to send to it IPv4 and MPLS packets, there will be two adjacencies; one for the IPv4 and one for the MPLS packets. The adjacencies are thus distinguished by the packets the carry, this is known as the adjacency's 'link-type'. It is not an L3 packet type, since the adjacency can have a link type of Ethernet (for L2 over GRE).
The discovery protocols are not aware of all the link types required - only the FIB is. the FIB will create adjacencies as and when they are required, and it is thus then desirable to 'pull' from the discovery protocol the re-write required. The alternative (that we have now) is that the discovery protocol pushes (i.e. creates) adjacencies for each link type - this creates more adjacencies than we need.
To pull, FIB now requests from the interface-type to 'complete' the adjacency. The interface can then delegate to the discovery protocol (on ethernet links) or directly build the re-write (i.e on GRE).

Change-Id: I61451789ae03f26b1012d8d6524007b769b6c6ee
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 2 insertions, 12 deletions

diff --git a/vnet/vnet/vxlan-gpe/vxlan_gpe.c b/vnet/vnet/vxlan-gpe/vxlan_gpe.c
index fae481c36bb..979864e9092 100644
--- a/vnet/vnet/vxlan-gpe/vxlan_gpe.c
+++ b/vnet/vnet/vxlan-gpe/vxlan_gpe.c
@@ -121,17 +121,6 @@ VNET_DEVICE_CLASS (vxlan_gpe_device_class,static) = {
   .admin_up_down_function = vxlan_gpe_interface_admin_up_down,
 };
 
-static uword dummy_set_rewrite (vnet_main_t * vnm,
-                                u32 sw_if_index,
-                                u32 l3_type,
-                                void * dst_address,
-                                void * rewrite,
-                                uword max_rewrite_bytes)
-{
-  return 0;
-}
-
-
 /**
  * @brief Formatting function for tracing VXLAN GPE with length
  *
@@ -151,7 +140,8 @@ static u8 * format_vxlan_gpe_header_with_length (u8 * s, va_list * args)
 VNET_HW_INTERFACE_CLASS (vxlan_gpe_hw_class) = {
   .name = "VXLAN_GPE",
   .format_header = format_vxlan_gpe_header_with_length,
-  .set_rewrite = dummy_set_rewrite,
+  .build_rewrite = default_build_rewrite,
+  .flags = VNET_HW_INTERFACE_CLASS_FLAG_P2P,
 };