Updated SNAT Spec

The pipeline is updated,
1) The extra table 43 is removed and 44 will continue as inbound table.
2) Now metadata will be set before submitting the packet to the
netfilter using set_field.

Change-Id: I7fedf702bfb37cd8a7bbb9eab545225ec393a004
Signed-off-by: Aswin Suryanarayanan <asuryana@redhat.com>

diff --git a/docs/specs/conntrack-based-snat.rst b/docs/specs/conntrack-based-snat.rst
index 84a7d231825a10e3ece4e5e878f98a8a444ceec9..c0e1b9f66b71b09036e51d0ea6f5631b6fc05504 100644 (file)
--- a/docs/specs/conntrack-based-snat.rst
+++ b/docs/specs/conntrack-based-snat.rst
@@ -74,21 +74,20 @@ elected.
 Pipeline changes
 ----------------
 The ovs based NAPT flows will replace the controller based NAPT flows. The changes are limited
-to the designated switch for the router. The NAPT INBOUND Table is changed from table 44 to 43
-for both the implementation. Below is the illustration for flat external network.
+to the designated switch for the router. Below is the illustration for flat external network.
 
 Outbound NAPT
 
 Table 26 (PSNAT Table)  => submits the packet to netfilter to check whether it is an existing
 connection. Resubmits the packet back to 46.
 
-Table 44 => The metadata will be swapped here to that of the external network and packet will
-be send to table 47.
+Table 46 (NAPT OUTBOUND TABLE) => if it is an established connection, it indicates the
+translation is done and the packet is forwarded to table 47 after writing the external network
+metadata.
 
-Table 46 (NAPT OUTBOUND TABLE) => if it is an established connection which indicates the
-translation is done and the packet is forwarded to table 44.
 If it is a new connection the connection will be committed to netfilter and this entry will be
-used for napt. The translated packet will be resubmitted to table 44.
+used for NAPT. The translated packet will be resubmitted to table 47. The external network
+metadata will be written before sending the packet to netfilter.
 
 Table 47 (NAPT FIB TABLE) => The translated packet will be sent to the egress group.
 
@@ -97,29 +96,25 @@ Sample Flows
 ::
 
  table=26, priority=5,ip,metadata=0x222e2/0xfffffffe actions=ct(table=46,zone=5003,nat)
- table=44, priority=5,ct_state=+snat,ip,metadata=0x222e2/0xfffffffe,nw_src=192.168.111.21 actions=write_metadata:0x222e0/0xfffffffe,goto_table:47
- table=46, priority=6,ct_state=+snat,ip actions=resubmit(,44)
- table=46, priority=5,ct_state=+new+trk,ip,metadata=0x222e2/0xfffffffe actions=ct(commit,table=44,zone=5003,nat(src=192.168.111.21))
- table=47, priority=6,ct_state=+snat,ip,nw_src=192.168.111.21 actions=group:200003
+ table=46, priority=6,ct_state=+snat,ip,metadata=0x222e2/0xfffffffe actions=set_field:0x222e0->metadata,resubmit(,47)
+ table=46, priority=5,ct_state=+new+trk,ip,metadata=0x222e2/0xfffffffe actions=set_field:0x222e0->metadata,ct(commit,table=47,zone=5003,nat(src=192.168.111.21))
+ table=47, n_packets=0, n_bytes=0, priority=6,ct_state=+snat,ip,nw_src=192.168.111.21 actions=group:200000
 
-Inbound NAPT
 
-Table 43 (NAPT INBOUND Table)=> submits the packet to netfilter to check for an existing
-connection. The packet will be submitted back to table 44.
+Inbound NAPT
 
-Table 44 => The metadata will be swapped here to that of the internal network and packet will
-be send to table 47.
+Table 44 (NAPT INBOUND Table)=> submits the packet to netfilter to check for an existing
+connection after changing the metadata to that of the internal network. The packet will be
+submitted back to table 47.
 
-Table 47 (NAPT FIB TABLE) => The translated packet will be sent to table 43 for writing the
-appropriate metadata and will be submitted back to table 21.
+Table 47 (NAPT FIB TABLE) => The translated packet will be submitted back to table 21.
 
 Sample Flows
 
 ::
 
- table=21, priority=42,ip,metadata=0x222e0/0xfffffffe,nw_dst=192.168.111.21 actions=resubmit(,43)
- table=43, priority=10,ip actions=ct(table=44,zone=5003,nat)
- table=44, priority=5,ct_state=+dnat,ip,metadata=0x222e0/0xfffffffe actions=write_metadata:0x222e2/0xfffffffe,goto_table:47
+ table=21, priority=42,ip,metadata=0x222e0/0xfffffffe,nw_dst=192.168.111.21 actions=resubmit(,44)
+ table=44, priority=10,ip,metadata=0x222e0/0xfffffffe,nw_dst=192.168.111.21 actions=set_field:0x222e2->metadata,ct(table=47,zone=5003,nat)
  table=47, priority=5,ct_state=+dnat,ip actions=resubmit(,21)
 
 Yang changes