mgmt+tools: allow MTU overrides on existing faces
refs #5056
Change-Id: I464a0c68773290bf1cfd0bf2afc4344e79fbb614
diff --git a/docs/manpages/nfdc-face.rst b/docs/manpages/nfdc-face.rst
index c00a6ce..c09191b 100644
--- a/docs/manpages/nfdc-face.rst
+++ b/docs/manpages/nfdc-face.rst
@@ -27,6 +27,8 @@
The **nfdc face show** command shows properties and statistics of one specific face.
The **nfdc face create** command creates a UDP unicast, TCP, or Ethernet unicast face.
+If the face already exists, the specified arguments will be used to update its properties, if
+possible.
Local FaceUri is required for creating Ethernet unicast faces; otherwise it must be omitted.
The NDNLPv2 unicast reliability feature may be explicitly enabled by specifying **reliability on**
or explicitly disabled by specifying **reliability off**.
@@ -38,11 +40,10 @@
default on all other face types.
Parameters for this feature can set with the **congestion-marking-interval** option (specified in
milliseconds) and the **default-congestion-threshold** option (specified in bytes).
-The MTUs of unicast Ethernet and UDP faces may be overridden using the **mtu** parameter (specified
-in bytes).
-However, a face may choose to limit the range of acceptable values for this parameter or disregard
-it altogether when setting its MTU.
-The MTU of an existing face may not be modified using this parameter and will result in an error.
+The effective MTUs of unicast Ethernet and UDP faces may be overridden using the **mtu** parameter
+(specified in bytes).
+The forwarder may limit the range of this override MTU and will use the minimum of it and the MTU
+of the underlying Ethernet or UDP transport.
The **nfdc face destroy** command destroys an existing face.
@@ -93,6 +94,12 @@
It is the maximum bound of the congestion threshold for the face, as well as the default
threshold used if the face does not support retrieving the capacity of the send queue.
+<MTU>
+ The MTU used to override the MTU of the underlying transport on Ethernet and UDP faces.
+ This MTU serves as an upper bound for the MTU provided by the transport.
+ The range of acceptable values may be limited by the forwarder.
+ To unset this override, specify the MTU as "auto".
+
EXIT CODES
----------
0: Success
@@ -135,8 +142,7 @@
Create a face with the specified remote FaceUri and explicitly disable congestion marking.
nfdc face create remote udp://router.example.net mtu 4000
- Create a face with the specified remote FaceUri and an MTU of 4000 bytes (which may be ignored
- or limited to within a certain range by the internal logic of the face).
+ Create a face with the specified remote FaceUri and set the override MTU to 4000 bytes.
nfdc face destroy 300
Destroy the face whose FaceId is 300.