Netmask for external bridge not set correctly

Netmask for external bridge not set correctly

I am trying to connect Xeon Phi coprocessors to an external bridge with a wider than default netmask. My bridge br0 on the host has IP with netmask (the first 14 bits set). When I configure MPSS 3.2, I do this:

[root@c001-n002 ~]# micctrl --addbridge=br0 --type=external --ip= --netbits=14

	[root@c001-n002 ~]# micctrl --network=static --bridge=br0 --ip=

	          mic0: Changing network to static bridge br0 at

	          mic1: Changing network to static bridge br0 at

	          mic2: Changing network to static bridge br0 at

	          mic3: Changing network to static bridge br0 at

Note that I do not have "netbits" in the second command, because if I put in "--netbits=14", micctrl responds "[Error] Adding an interface to a bridge will use the bridges netmask - ignoring netbits 14". The bridged configuration succeeds, however, on Xeon Phi, the interface mic0 is configured with a netmask of, which is incorrect.

[root@c001-n002 ~]# service mpss start

	Starting Intel(R) MPSS:                                    [  OK  ]

	mic0: online (mode: linux image: /usr/share/mpss/boot/bzImage-knightscorner)

	mic1: online (mode: linux image: /usr/share/mpss/boot/bzImage-knightscorner)

	mic2: online (mode: linux image: /usr/share/mpss/boot/bzImage-knightscorner)

	mic3: online (mode: linux image: /usr/share/mpss/boot/bzImage-knightscorner)

	[root@c001-n002 ~]# ssh mic0 ifconfig mic0

	mic0      Link encap:Ethernet  HWaddr 4C:79:BA:24:10:BA  

	          inet addr:  Bcast:  Mask:

	          UP BROADCAST RUNNING  MTU:1500  Metric:1

	          RX packets:143 errors:0 dropped:0 overruns:0 frame:0

	          TX packets:71 errors:0 dropped:0 overruns:0 carrier:0

	          collisions:0 txqueuelen:1000

	          RX bytes:14910 (14.5 KiB)  TX bytes:10696 (10.4 KiB)


As a result, I cannot ping addresses outside of from mic0 ("connect: Network is unreachable"). How do I convince micctrl to use a netmask of for interface mic0 in uOS?


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Hi Andrey,

There is a whitepaper discussing on how to configure the coprocessors in a cluster (link here ). Have you looked at this document yet? Thank you.

I read this paper every morning (almost), but it is old in the sense that it uses MPSS Gold, and a lot of things have changed. What authors do there is they hack into the MIC filesystem tree to change the netmask in the interface configuration files. One should not have to resort to such inconvenient measures (and they are difficult to automate), especially when micctl has an argument to do it, and also because it claims that it will use the bridge's netmask.

The reason for my question is to verify that I am using micctrl correctly, and if I am doing it right, there is probably a bug in this tool.


Hi Andrey,

I get the same error when I try that command. Let me ask someone who know more about micctrl. Thank you.  

For your information, I generated a ticket in our system to track this defect (# 4868788). Thank you.

Thank you very much, Loc!

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