doc: add notes for ead-es-frag fragmentation

Config for -
1. Preventing fragmentation via user configured EAD RTs
2. Limiting the number of EVIs per-fragment if EAD fragmentation is needed

Signed-off-by: Anuradha Karuppiah <anuradhak@nvidia.com>

diff --git a/doc/user/bgp.rst b/doc/user/bgp.rst
index 7d7335a23f0a2f267a4b1c314aec929f4b9d5584..b9733cd522fec8844ed231671bbb7b6950c4022d 100644 (file)
--- a/doc/user/bgp.rst
+++ b/doc/user/bgp.rst
@@ -2935,6 +2935,8 @@ Example configuration:
     exit-address-family
    !
 
+.. _bgp-evpn-mh:
+
 EVPN Multihoming
 ^^^^^^^^^^^^^^^^
 
@@ -3045,6 +3047,55 @@ following zebra command -
 
 .. clicmd:: evpn mh startup-delay (0-3600)
 
+EAD-per-ES fragmentation
+""""""""""""""""""""""""
+The EAD-per-ES route carries the EVI route targets for all the broadcast
+domains associated with the ES. Depending on the EVI scale the EAD-per-ES
+route maybe fragmented.
+
+The number of EVIs per-EAD route can be configured via the following
+BGP command -
+
+.. index:: [no] ead-es-frag evi-limit(1-1000)
+.. clicmd:: [no] ead-es-frag evi-limit(1-1000)
+
+Sample Configuration
+^^^^^^^^^^^^^^^^^^^^^
+.. code-block:: frr
+
+    !
+    router bgp 5556
+     !
+     address-family l2vpn evpn
+      ead-es-frag evi-limit 200
+     exit-address-family
+     !
+    !
+
+EAD-per-ES route-target
+"""""""""""""""""""""""
+The EAD-per-ES route by default carries all the EVI route targets. Depending
+on EVI scale that can result in route fragmentation. In some cases it maybe
+necessary to avoid this fragmentation and that can be done via the following
+workaround -
+1. Configure a single supplementary BD per-tenant VRF. This SBD needs to
+be provisioned on all EVPN PEs associated with the tenant-VRF.
+2. Config the SBD's RT as the EAD-per-ES route's export RT.
+
+Sample Configuration
+^^^^^^^^^^^^^^^^^^^^^
+.. code-block:: frr
+
+    !
+    router bgp 5556
+     !
+     address-family l2vpn evpn
+      ead-es-route-target export 5556:1001
+      ead-es-route-target export 5556:1004
+      ead-es-route-target export 5556:1008
+     exit-address-family
+    !
+
 Support with VRF network namespace backend
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 It is possible to separate overlay networks contained in VXLAN interfaces from