diff --git a/apstra/apstra_validator/forbidden_when_value_is.go b/apstra/apstra_validator/forbidden_when_value_is.go
index 75ce298d..b58b888d 100644
--- a/apstra/apstra_validator/forbidden_when_value_is.go
+++ b/apstra/apstra_validator/forbidden_when_value_is.go
@@ -68,8 +68,7 @@ func (o ForbiddenWhenValueIsValidator) Validate(ctx context.Context, req Forbidd
 
 			// get the attribute we'll be checking against
 			var mpVal attr.Value
-			diags = req.Config.GetAttribute(ctx, mp, &mpVal)
-			resp.Diagnostics.Append(diags...)
+			resp.Diagnostics.Append(req.Config.GetAttribute(ctx, mp, &mpVal)...)
 			if diags.HasError() {
 				continue // Collect all errors
 			}
@@ -83,7 +82,7 @@ func (o ForbiddenWhenValueIsValidator) Validate(ctx context.Context, req Forbidd
 			if o.Value.Equal(mpVal) {
 				resp.Diagnostics.Append(validatordiag.InvalidAttributeCombinationDiagnostic(
 					req.Path,
-					fmt.Sprintf("value not permitted when %q has value %s, got %q", mp, mpVal, req.ConfigValue),
+					fmt.Sprintf("attribute %q must be <null> when %q has value %s, got: %q", req.Path, mp, mpVal, req.ConfigValue),
 				))
 			}
 		}
diff --git a/apstra/apstra_validator/switch_lag_info.go b/apstra/apstra_validator/switch_lag_info.go
deleted file mode 100644
index 8f618b5c..00000000
--- a/apstra/apstra_validator/switch_lag_info.go
+++ /dev/null
@@ -1,57 +0,0 @@
-package apstravalidator
-
-import (
-	"context"
-	"fmt"
-	"github.com/hashicorp/terraform-plugin-framework/schema/validator"
-	"github.com/hashicorp/terraform-plugin-framework/types"
-)
-
-var _ validator.Object = SwitchLagInfoValidator{}
-
-type SwitchLagInfoValidator struct {
-	redundancyProtocol string
-}
-
-func (o SwitchLagInfoValidator) Description(_ context.Context) string {
-	return fmt.Sprintf("Ensures the sibling attribute 'redundancy_protocol' is set to '%s'.", o.redundancyProtocol)
-}
-
-func (o SwitchLagInfoValidator) MarkdownDescription(ctx context.Context) string {
-	return o.Description(ctx)
-}
-
-func (o SwitchLagInfoValidator) ValidateObject(ctx context.Context, req validator.ObjectRequest, resp *validator.ObjectResponse) {
-	if req.ConfigValue.IsNull() || req.ConfigValue.IsUnknown() {
-		return
-	}
-
-	redundancyProtocolPath := req.Path.ParentPath().AtName("redundancy_protocol")
-
-	var redundancyProtocol types.String
-	resp.Diagnostics.Append(req.Config.GetAttribute(ctx, redundancyProtocolPath, &redundancyProtocol)...)
-	if resp.Diagnostics.HasError() {
-		return
-	}
-
-	if redundancyProtocol.IsNull() || redundancyProtocol.IsUnknown() {
-		resp.Diagnostics.AddAttributeError(
-			req.Path, errInvalidConfig,
-			fmt.Sprintf("configuring '%s' requires '%s' = '%s'", req.Path.String(), redundancyProtocolPath.String(), o.redundancyProtocol),
-		)
-		return
-	}
-
-	if redundancyProtocol.ValueString() != o.redundancyProtocol {
-		resp.Diagnostics.AddAttributeError(
-			req.Path, errInvalidConfig,
-			fmt.Sprintf("configuring '%s' requires '%s' = '%s'", req.Path.String(), redundancyProtocolPath.String(), o.redundancyProtocol),
-		)
-	}
-}
-
-func ValidateSwitchLagInfo(m string) validator.Object {
-	return SwitchLagInfoValidator{
-		redundancyProtocol: m,
-	}
-}
diff --git a/apstra/design/rack_type_leaf_switch.go b/apstra/design/rack_type_leaf_switch.go
index 7977804e..1a130f34 100644
--- a/apstra/design/rack_type_leaf_switch.go
+++ b/apstra/design/rack_type_leaf_switch.go
@@ -108,7 +108,9 @@ func (o LeafSwitch) ResourceAttributes() map[string]resourceSchema.Attribute {
 			Optional:   true,
 			Attributes: MlagInfo{}.ResourceAttributes(),
 			Validators: []validator.Object{
-				apstravalidator.ValidateSwitchLagInfo(apstra.LeafRedundancyProtocolMlag.String()),
+				apstravalidator.RequiredWhenValueIs(path.MatchRelative().AtParent().AtName("redundancy_protocol"), types.StringValue(apstra.LeafRedundancyProtocolMlag.String())),
+				apstravalidator.ForbiddenWhenValueIs(path.MatchRelative().AtParent().AtName("redundancy_protocol"), types.StringValue(apstra.LeafRedundancyProtocolEsi.String())),
+				apstravalidator.ForbiddenWhenValueIs(path.MatchRelative().AtParent().AtName("redundancy_protocol"), types.StringNull()),
 			},
 		},
 		"redundancy_protocol": resourceSchema.StringAttribute{