zebra: fix the bug zebra installs more ECMP next hops than specified #20364
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…in linux platform Ensure the number of installed ECMP next hops does not exceed zrouter.zav.multipath_num by stopping iteration once the limit is reached, matching OpenBSD behavior (see zebra_mpls_openbsd.c:250–251). Signed-off-by: Bing Shui <[email protected]>
donaldsharp
reviewed
Jan 5, 2026
| if (!nexthop) | ||
| continue; | ||
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| if (nexthop_num >= zrouter.zav.multipath_num) |
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Do you have an example of this actually being wrong? Or is this just done from code inspection?
This is far too late in the install process. This is a Control plane enforcement issue not a dplane enforcement issue. This should be up in the zebra proper as part of one of the final steps/checks of a route that is about to be installed. This is because FRR supports a variety of data plane plugins/ architectures and each of them should not have to have this check.
I suspect that the zebra_mpls_openbsd.c check is a hold over from before the code became more stringent about checking this.
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Ensure the number of installed ECMP next hops does not exceed zrouter.zav.multipath_num by stopping iteration once the limit is reached, matching OpenBSD behavior (see zebra_mpls_openbsd.c:250–251).