Readme update for link-bandwidth handling (#3496)

* Add tests for checking different load balancing weights using bgp link bandwidth community

---------

Co-authored-by: Pramod Maurya <pramodmaurya@google.com>
Co-authored-by: Darren Loher <dloher@google.com>

feature/bgp/multipath/otg_tests/bgp_multipath_wecmp_lbw_community_test/README.md

@@ -4,6 +4,8 @@
 
 Validate BGP in multipath UCMP support with link bandwidth community
 
+NOTE: [TODO] items are tracked at https://github.com/openconfig/featureprofiles/issues/3520
+
 ## Testbed type
 
 [TESTBED_DUT_ATE_4LINKS](https://github.com/openconfig/featureprofiles/blob/main/topologies/atedut_4.testbed)
@@ -19,43 +21,104 @@ Validate BGP in multipath UCMP support with link bandwidth community
     *   ATE port-2 and DUT port-2
     *   ATE port-3 and DUT port-3
 *   Enable an Accept-route all import-policy/export-policy for eBGP session
-    under the neighbor AFI/SAFI
-*   Create an IPv4 internal target network attached to ATE port 2 and 3
+    under the neighbor AFI/SAFI - IPv6 unicast and IPv4 unicast.
+*   Create an single IPv4 internal target network attached to ATE port 2 and 3
+*   [TODO] Create an single IPv6 internal target network attached to ATE port 2 and 3
+
 
 ### Tests
 
-*   RT-1.52.1: Verify use of community type
-
-    *   Configure ATE port 1, 2 and 3 on different AS
-    *   Enable multipath, set maximum-paths limit to 2, enable allow multiple
-        AS, and send community type to BOTH (STANDARD and EXTENDED)
-        *   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/afi-safis/afi-safi/use-multiple-paths/config/enabled
-        *   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/afi-safis/afi-safi/use-multiple-paths/ebgp/config/allow-multiple-as
-        *   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/afi-safis/afi-safi/use-multiple-paths/ebgp/config/maximum-paths
-        *   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/config/send-community-type
-        *   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/use-multiple-paths/ebgp/link-bandwidth-ext-community/config/enabled
-    *   Advertise equal cost paths from port2 and port3 of ATE
-    *   Check entries in FIB for advertised prefix, it should have 2 entries
-        *   /network-instances/network-instance/afts/next-hop-groups/next-hop-group/next-hops
-    *   Initiate traffic from ATE port-1 to the DUT and destined to internal
-        target network
-    *   Check entire traffic should only be unequally forwarded between DUT
-        port2 and port3
+*   RT-1.52.1: Verify use of unequal community type
+
+    *   Test Configuration
+        *   Configure ATE port 1, 2 and 3 on different AS, with boths AFI/SAFI
+            * Advertise IPv4 and IPv6 internal target, both, form both ATE port-1 and ATE port-2 in eBGP.
+            * [TODO] For ATE port 2 attach `link-bandwidth:23456:10K` extended-community
+            * [TODO] For ATE port 3 attach `link-bandwidth:23456:5K` extended-community
+        *   Enable multipath, set maximum-paths limit to 2, enable allow multiple
+            AS, and send community type to [STANDARD, EXTENDED, LARGE]
+            *   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/afi-safis/afi-safi/use-multiple-paths/config/enabled
+            *   [TODO] /network-instances/network-instance/protocols/protocol/bgp/global/afi-safis/afi-safi/use-multiple-paths/ebgp/config/allow-multiple-as
+            *   [TODO] /network-instances/network-instance/protocols/protocol/bgp/globalp/afi-safis/afi-safi/use-multiple-paths/ebgp/config/maximum-paths
+            *   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/config/send-community-type
+            *   /network-instances/network-instance/protocols/protocol/bgp/global/use-multiple-paths/ebgp/link-bandwidth-ext-community/config/enabled
+        *   Advertise equal cost paths from port2 and port3 of ATE
+        *   Initiate traffic from ATE port-1 to the DUT and destined to internal
+            target network. 
+            *   Use UDP traffic with src and dst port randomly selected from 1-65535 range for each packet. Or equivalent pattern guaranteeng high entropy of traffic.
+    * Behaviour Validation
+        *   Check entries in AFT for advertised prefix, it should have 2 entries.\
+            [TODO] The `weight` leafs of next-hops shall be in 2:1 ratio.
+            *   Find next-hop-group IDs for both internal target networks:
+                *   /network-instances/network-instance/afts/ipv4-unicast/ipv4-entry[prefix=IPv4 internal target network]/state/**next-hop-group**
+                *   /network-instances/network-instance/afts/ipv4-unicast/ipv4-entry[prefix=IPv6 internal target network]/state/**next-hop-group**
+            *   using next-hop-group as key find number and weight of next-hops of both internal target network
+                *   /network-instances/network-instance/afts/next-hop-groups/next-hop-group[id=next-hop-group ID]/next-hops/next-hop/state/index
+                *   /network-instances/network-instance/afts/next-hop-groups/next-hop-group[id=next-hop-group ID]/next-hops/next-hop/state/**weight**
+        *   [TODO] Check entire traffic should  be unequally forwarded between DUT
+            port2 and port3 only
+                *   66% via port2
+                *   33% via port3
+                *   with +/-5% tolerance
+
+*   [TODO] RT-1.52.2: Verify use of equal community type
+
+    *   Test Configuration
+        Use test configuration as in RT-1.52.1 above with following modifications:
+        * Advertise IPv4 and IPv6 internal target, both, form both ATE port-1 and ATE port-2 in eBGP.
+                * For ATE port 2 attach `link-bandwidth:23456:10K` extended-community
+                * For ATE port 3 attach `link-bandwidth:23456:10K` extended-community
+    *   Behaviour Validation
+        *   Check entries in AFT for advertised prefix, it should have 2 entries.\
+            [TODO] The `weight` leafs of next-hops shall be in 1:1 ratio.
+            *   Find next-hop-group IDs for both internal target networks:
+                *   /network-instances/network-instance/afts/ipv4-unicast/ipv4-entry[prefix=IPv4 internal target network]/state/**next-hop-group**
+                *   /network-instances/network-instance/afts/ipv4-unicast/ipv4-entry[prefix=IPv6 internal target network]/state/**next-hop-group**
+            *   using next-hop-group as key find number and weight of next-hops of both internal target network
+                *   /network-instances/network-instance/afts/next-hop-groups/next-hop-group[id=next-hop-group ID]/next-hops/next-hop/state/index
+                *   /network-instances/network-instance/afts/next-hop-groups/next-hop-group[id=next-hop-group ID]/next-hops/next-hop/state/**weight**
+        *   [TODO] Check entire traffic should  be unequally forwarded between DUT
+            port2 and port3 only
+            *   50% via port2
+            *   50% via port3
+            *   with +/-5% tolerance
+
+*   [TODO] RT-1.52.3: Verify BGP multipath when some path missing link-bandwidth extended-community
+
+    *   Test Configuration
+        Use test configuration as in RT-1.52.1 above with following modifications:
+        *   Configure ATE port 1, 2 and 3 on different AS, with boths AFI/SAFI
+            * Advertise IPv4 and IPv6 internal target, both, form both ATE port-1 and ATE port-2 in eBGP.
+            * For ATE port 2 attach `link-bandwidth:23456:10K` extended-community
+            * For ATE port 3 **DO NOT** attach any link-bandwidth extended-community
+    *   Behaviour Validation
+        *   Check entries in AFT for advertised prefix, it should have 2 entries.\
+            [TODO] The `weight` leafs of next-hops shall be in 1:1 ratio.
+            *   Find next-hop-group IDs for both internal target networks:
+                *   /network-instances/network-instance/afts/ipv4-unicast/ipv4-entry[prefix=IPv4 internal target network]/state/**next-hop-group**
+                *   /network-instances/network-instance/afts/ipv4-unicast/ipv4-entry[prefix=IPv6 internal target network]/state/**next-hop-group**
+            *   using next-hop-group as key find number and weight of next-hops of both internal target network
+                *   /network-instances/network-instance/afts/next-hop-groups/next-hop-group[id=next-hop-group ID]/next-hops/next-hop/state/index
+                *   /network-instances/network-instance/afts/next-hop-groups/next-hop-group[id=next-hop-group ID]/next-hops/next-hop/state/**weight**
+        *   [TODO] Check entire traffic should  be unequally forwarded between DUT
+            port2 and port3 only
+            *   50% via port2
+            *   50% via port3
+            *   with +/-5% tolerance
+
 
 ## Config Parameter Coverage
 
 *   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/afi-safis/afi-safi/use-multiple-paths/config/enabled
-*   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/afi-safis/afi-safi/use-multiple-paths/ebgp/config/allow-multiple-as
-*   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/afi-safis/afi-safi/use-multiple-paths/ebgp/config/maximum-paths
+*   /network-instances/network-instance/protocols/protocol/bgp/global/afi-safis/afi-safi/use-multiple-paths/ebgp/config/allow-multiple-as
+*   /network-instances/network-instance/protocols/protocol/bgp/global/afi-safis/afi-safi/use-multiple-paths/ebgp/config/maximum-paths
 *   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/config/send-community-type
-*   /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/use-multiple-paths/ebgp/link-bandwidth-ext-community/config/enabled
+*   /network-instances/network-instance/protocols/protocol/bgp/global/use-multiple-paths/ebgp/link-bandwidth-ext-community/config/enabled
 
 ## Telemetry Parameter Coverage
 
-*   /network-instances/network-instance/afts/ipv4-unicast/ipv4-entry/state
 *   /network-instances/network-instance/afts/ipv4-unicast/ipv4-entry/state/next-hop-group
-*   /network-instances/network-instance/afts/next-hop-groups/next-hop-group[id=<id>]/state
-*   /network-instances/network-instance/afts/next-hop-groups/next-hop-group/next-hops
+*   /network-instances/network-instance/afts/next-hop-groups/next-hop-group[id=<id>]/next-hops/next-hop[index=<index>]/state/weight
 
 ## OpenConfig Path and RPC Coverage