[FRR]Setting multipath size to 514 and disabling bgp-vnc for optimiza…

…tion (sonic-net#20744)

- Why I did it
Increased the max multipath to 512. In addition removed bgp-vnc as this feature is not used by SONiC .
https://docs.frrouting.org/en/latest/vnc.html#vnc-and-vnc-gw
This feature adds overhead in general and removing this improves bgp convergence time for scale.

- How I did it
Added a patch modify debian rules.

- How to verify it
Run BGP tests in scaled topology.

src/sonic-frr/patch/0061-Set-multipath-to-514-and-disable-bgp-vnc-for-optimiz.patch

@@ -0,0 +1,23 @@
+From 501f267ec4c7359fc518ba31c5d63045c935045c Mon Sep 17 00:00:00 2001
+From: dgsudharsan <[email protected]>
+Date: Wed, 4 Dec 2024 20:39:46 +0000
+Subject: [PATCH] Set multipath to 514 and disable bgp-vnc for optimization
+
+
+diff --git a/debian/rules b/debian/rules
+index 5a8199afb7..3d762e6df1 100755
+--- a/debian/rules
++++ b/debian/rules
+@@ -66,8 +66,7 @@ override_dh_auto_configure:
+ 		--disable-protobuf \
+ 		--disable-zeromq \
+ 		--enable-ospfapi \
+-		--enable-bgp-vnc \
+-		--enable-multipath=256 \
++		--enable-multipath=514 \
+ 		\
+ 		--enable-user=frr \
+ 		--enable-group=frr \
+-- 
+2.43.2
+

src/sonic-frr/patch/series

@@ -40,3 +40,4 @@
 0058-When-the-file-is-config-replayed-we-cannot-handle-th.patch
 0059-Fix-BGP-reset-on-suppress-fib-pending-configuration.patch
 0060-bgpd-Validate-both-nexthop-information-NEXTHOP-and-N.patch
+0061-Set-multipath-to-514-and-disable-bgp-vnc-for-optimiz.patch