diff --git a/etc/tempest.conf.sample b/etc/tempest.conf.sample
index 02bfdcb..9280c57 100644
--- a/etc/tempest.conf.sample
+++ b/etc/tempest.conf.sample
@@ -178,7 +178,7 @@
 tenant_network_cidr = 10.100.0.0/16
 
 # The mask bits used to partition the tenant block.
-tenant_network_mask_bits = 29
+tenant_network_mask_bits = 28
 
 # If tenant networks are reachable, connectivity checks will be
 # performed directly against addresses on those networks.