Add BGP Suppress FIB Pending test plan

docs/testplan/BGP-Suppress-FIB-Pending-test-plan.md

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+# BGP Suppress FIB Pending Test Plan
+
+## Related documents
+
+| **Document Name** | **Link** |
+|-------------------|----------|
+| BGP Suppress FIB Pending HLD | [https://github.com/stepanblyschak/SONiC/blob/bgp-suppress-fib-pending/doc/BGP/BGP-supress-fib-pending.md]|
+
+## Overview
+
+As of today, SONiC BGP advertises learnt prefixes regardless of whether these prefixes were successfully programmed into ASIC.
+While route programming failure is followed by orchagent crash and all services restart, even for successfully created routes there is a short period of time when the peer will be black holing traffic.
+Also, in the following scenario, a credit loop occurs:
+###### Figure 1. Use case scenario
+
+![Use case scenario](Img/Bgp_Suppress_FIB_Pending_Use_Case.png)
+
+The problem with BGP programming occurs after the T1 switch is rebooted:
+1. First, the T1 FRR learns a default route from at least 1 T2
+2. The T0 advertises it’s prefixes to T1
+3. FRR advertises the prefixes to T2 without waiting for them to be programmed in the ASIC
+4. T2 starts forwarding traffic for prefixes not yet programmed, according to T1’s routing table, T1 sends it back to a default route – same T2
+
+To avoid that, the route programming has to be synchronous down to the ASIC to avoid credit loops.
+
+### Scope
+
+The test is to verify the mechanism that allows BGP not to advertise routes that haven't been installed into ASIC yet.
+
+### Scale / Performance
+
+No scale/performance test involved in this test plan
+
+### Related **DUT** CLI commands
+Command to enable the feature:
+```
+admin@sonic:~$ sudo config suppress-fib-pending enabled
+```
+Command to disable the feature:
+```
+admin@sonic:~$ sudo config suppress-fib-pending disabled
+```
+
+### Supported Topology
+The tests will be supported on t1 topo.
+
+###### Figure 2. Logic Topology
+![Use case scenario](Img/BGP_Suppress_FIB_Pending_Topo.png)
+
+## Test cases
+### Test case # 1 - BGPv4 route suppress test
+1. Enable BGP suppress-fib-pending function at DUT
+2. Save configuration and execute one action randomly choosen from(__reboot__/__config reload__/__fast-reboot__/__warm-reboot__)
+3. Suspend orchagent process to simulate a delay
+```
+kill -SIGSTOP $(pidof orchagent)
+```
+4. Announce BGP ipv4 prefixes to DUT from T0 VM by exabgp
+5. Make sure announced BGP routes are in __queued__ state in the DUT routing table
+6. Verify the routes are not announced to T2 VM peer
+7. Send traffic matching the prefixes and verify packets are not forwarded to T0 VM
+8. Restore orchagent process
+```
+kill -SIGCONT $(pidof orchagent)
+```
+9. Make sure announced BGP routes are not in __queued__ state in the DUT routing table
+10. Make sure the routes are programmed in FIB by checking __offloaded__ flag in the DUT routing table
+```
+show ip route 1.1.1.0/24 json
+
+{
+    "1.1.1.0/24": [
+        {
+            "destSelected": true,
+            "distance": 20,
+            "installed": true,
+            "installedNexthopGroupId": 277,
+            "internalFlags": 264,
+            "internalNextHopActiveNum": 1,
+            "internalNextHopNum": 1,
+            "internalStatus": 80,
+            "metric": 0,
+            "nexthopGroupId": 277,
+            "nexthops": [
+                {
+                    "active": true,
+                    "afi": "ipv4",
+                    "fib": true,
+                    "flags": 3,
+                    "interfaceIndex": 17,
+                    "interfaceName": "PortChannel1021",
+                    "ip": "10.0.0.65",
+                    "weight": 1
+                }
+            ],
+            "offloaded": true,
+            "prefix": "1.1.1.0/24",
+            "prefixLen": 24,
+            "protocol": "bgp",
+            "selected": true,
+            "table": 254,
+            "uptime": "00:08:08",
+            "vrfId": 0,
+            "vrfName": "default"
+        }
+    ]
+}
+```
+11. Verify the routes are announced to T2 peer
+12. Send traffic matching the prefixes and verify packets are forwarded to T0 VM
+13. This test should cover __default__ and __user defined vrf__
+
+### Test case # 2 - BGPv6 route suppress test
+1. Enable BGP suppress-fib-pending function at DUT
+2. Save configuration and execute one action randomly choosen from(__reboot__/__config reload__/__fast-reboot__/__warm-reboot__)
+3. Suspend orchagent process to simulate a delay
+4. Announce BGP ipv6 prefixes to DUT from T0 VM by exabgp
+5. Make sure announced BGP routes are in __queued__ state in the DUT routing table
+6. Verify the routes are not announced to T2 VM peer
+7. Send traffic matching the prefixes and verify packets are not forwarded to T0 VM
+8. Restore orchagent process
+9. Make sure announced BGP routes are not in __queued__ state in the DUT routing table
+10. Make sure the routes are programmed in FIB by checking __offloaded__ flag in the DUT routing table
+11. Verify the routes are announced to T2 peer
+12. Send traffic matching the prefixes and verify packets are forwarded to T0 VM
+13. This test should cover __default__ and __user defined vrf__
+
+### Test case # 3 - Test BGP route without suppress
+1. No BGP suppress-fib-pending function configured at DUT
+2. Suspend orchagent process to simulate a delay
+3. Announce BGP prefixes to DUT from T0 VM by exabgp
+4. Make sure announced BGP routes are not in __queued__ state in the DUT routing table
+5. Verify the BGP routes are announced to T2 peer
+6. Restore orchagent process
+7. Make sure the routes are programmed in FIB by checking __offloaded__ flag in the DUT routing table
+8. Send traffic matching the prefixes and verify packets are forwarded to T0 VM
+
+### Test case # 4 - Test BGP test work with suppress
+1. No BGP suppress-fib-pending function configured at DUT
+2. Run BGP test suite
+3. Make sure BGP tests are not affected
+4. Enable BGP suppress-fib-pending function at DUT
+5. Run BGP test suite
+6. Make sure BGP tests are not affected
+
+### Test case # 5 - Test BGP route suppress under negative operation
+1. Enable BGP suppress-fib-pending function at DUT
+2. Suspend orchagent process to simulate a delay
+3. Announce BGP prefixes to DUT from T0 VM by exabgp
+4. Execute __BGP session restart__
+5. Verify BGP neighborships are established
+6. Make sure announced BGP routes are in __queued__ state in the DUT routing table
+7. Configure __static routes__ then redistribute to BGP
+8. Verify the __redistributed routes__ are in the DUT routing table
+9. Verify the routes are announced to T2 VM peer
+10. Send traffic matching the prefixes and verify packets are not forwarded to T0 VM
+11. Restore orchagent process
+12. Make sure announced BGP routes are not in queued state in the DUT routing table
+13. Make sure the routes are programmed in FIB by checking __offloaded__ flag in the DUT routing table
+14. Verify the BGP routes are announced to T2 peer
+15. Send traffic matching the prefixes and verify packets are forwarded to T0 VM
+
+### Test case # 6 - Test BGP route suppress in credit loops scenario
+1. No BGP suppress-fib-pending function configured at DUT
+2. Suspend orchagent process to simulate a delay
+3. Announce a default route to DUT from T2 VM
+4. Announce BGP prefixes to DUT from T0 VM by exabgp
+5. Verify the BGP routes are announced to T2 VM peer
+6. Send traffic matching the prefixes and verify packets are forwarded __back to T2 VM__
+7. Enable BGP suppress-fib-pending function at DUT
+8. Restore orchagent process
+9. Make sure the routes are programmed in FIB by checking __offloaded__ flag in the DUT routing table
+10. Send traffic matching the prefixes and verify packets are forwarded to __T0 VM__