Re: Linux CentOS 7.3 can get DHCP IPv4 IP address with configuring DHCP server as per RFC3021

["Fu, Siyuan" <siyuan.fu@intel.com>]

Hi, Karunakar

We haven't received requirement for this feature before so we don't have plan now. I think you can submit a Bugzilla ticket for this feature request, we will follow up to investigate it.

BestRegards
Fu Siyuan

From: Karunakar P [mailto:karunakarp@amiindia.co.in]
Sent: Monday, September 25, 2017 4:54 PM
To: Fu, Siyuan <siyuan.fu@intel.com>; 'edk2-devel@lists.01.org' <edk2-devel@lists.01.org>
Cc: Wu, Jiaxin <jiaxin.wu@intel.com>; Ye, Ting <ting.ye@intel.com>
Subject: RE: Linux CentOS 7.3 can get DHCP IPv4 IP address with configuring DHCP server as per RFC3021

Hi Fu Siyuan,

Thanks for your conformation.

We would like to use /31s to save IPv4 addresses.

When it's a point-to-point link (server to router), the extra network address and broadcast address is wasted.
RFC 3021 solves the problem by using a broadcast address of 255.255.255.255 on such subnets.

We have a requirement to support this, do you have any plan to support RFC3021 ? Given the requirement time consuming how hard to implement this ?

Thanks,
karunakar

From: Fu, Siyuan [mailto:siyuan.fu@intel.com]
Sent: Monday, September 25, 2017 1:28 PM
To: Karunakar P; 'edk2-devel@lists.01.org'
Cc: Wu, Jiaxin; Ye, Ting
Subject: RE: Linux CentOS 7.3 can get DHCP IPv4 IP address with configuring DHCP server as per RFC3021

Hi, Karunakar

May I know that whether you have a real requirement that must use the point-2-point link in your environment, or you just found this problem in your test?

BestRegards
Fu Siyuan

From: Fu, Siyuan
Sent: Monday, September 25, 2017 3:50 PM
To: Karunakar P <karunakarp@amiindia.co.in<mailto:karunakarp@amiindia.co.in>>; 'edk2-devel@lists.01.org' <edk2-devel@lists.01.org<mailto:edk2-devel@lists.01.org>>
Cc: Wu, Jiaxin <jiaxin.wu@intel.com<mailto:jiaxin.wu@intel.com>>; Ye, Ting <ting.ye@intel.com<mailto:ting.ye@intel.com>>
Subject: RE: Linux CentOS 7.3 can get DHCP IPv4 IP address with configuring DHCP server as per RFC3021

Hi, Karunakar

You are correct that EDK2 doesn't support rfc3201.

The most obvious problem that come to my mind is the NetIp4IsUnicast() function in NetLib, which has the assumption that the host address part should not be all zero or all one (or to say, -1 in the rfc3201). I think that's why the PXE failed, but Cent OS could use IP address from the same DHCP server.

This is just an example, there may be some other places in edk2 network stack which have the same assumption, I'm not sure about this. Anyway, we never considered the point-2-point link in edk2.


BestRegards
Fu Siyuan

From: Karunakar P [mailto:karunakarp@amiindia.co.in]
Sent: Monday, September 25, 2017 3:02 PM
To: 'edk2-devel@lists.01.org' <edk2-devel@lists.01.org<mailto:edk2-devel@lists.01.org>>
Cc: Wu, Jiaxin <jiaxin.wu@intel.com<mailto:jiaxin.wu@intel.com>>; Fu, Siyuan <siyuan.fu@intel.com<mailto:siyuan.fu@intel.com>>; Ye, Ting <ting.ye@intel.com<mailto:ting.ye@intel.com>>
Subject: Re: Linux CentOS 7.3 can get DHCP IPv4 IP address with configuring DHCP server as per RFC3021

Hello All,

It is known that current EDKII doesn't support RFC3021, We could see the following behavior which is PXE boot fails whereas Cent OS can get IP address from the same BIOS.


[Configuration Used]

DHCP server setting under Ubuntu:
1. /etc/dhcp/dhcpd.conf

# RFC3021-Using 31-bit perfixes on IPv4 Point-to-Point Links
subnet 192.168.1.0 netmask 255.255.255.254 {
range 192.168.1.1 192.168.1.1;
next-server 192.168.1.0;
filename "EFI/BOOT/BOOTAA64.EFI";
option subnet-mask 255.255.255.254;
option routers 192.168.1.0;
}

2. /etc/network/interfaces
auto eth0
iface eth0 inet static
address 192.168.1.0
netmask 255.255.255.254
network 192.168.1.0


If the DHCP server and network interface are set up above configuration. Below are my test results and questions


1.      CentOS  7.3 (pre-installed) was able to retrieve IP through DHCP when they connect HDD to the SUT where PXE is failing.

2.      Could you please suggest what could be the reason behind this?


Thanks,
karunakar