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PXE boot problem: guest VM DHCP request packets not able to reach DHCP server

Alex12Aug 18 2013 — edited Aug 18 2013

Hi Gurus,

  I'm wondering if anyone could help me with this problem. I wanted to install Linux on Oracle VMs using PXE. I set up a DHCP server and the OVM running RHEL6.4 box. The DHCP server worked fine since other PHYSICAL servers could get IPs from this DHCP server. However, DHCP requests from Oracle VMs was not able to reach the DHCP server. So I suspect this is a VM-specific issue.

If I type in "dhcp net0" on gPXE prompt on the OVS machine(sappire), I can see the requests were being sent from the OVS server (sapphire):

gPXE> dhcp net0
DHCP (net0 00:21:f6:00:00:00) .............................................Connection time out (0x4c106035)
Could not configure net0: Connection time out (0x4c106035)
gPXE>

[root@sapphire ~]# tcpdump -i any -n udp dst portrange 67-68
tcpdump: WARNING: Promiscuous mode not supported on the "any" device
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on any, link-type LINUX_SLL (Linux cooked), capture size 96 bytes
20:47:25.606400 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:21:f6:00:00:00, length: 387
20:47:25.606549 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:21:f6:00:00:00, length: 387
20:47:25.606559 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:21:f6:00:00:00, length: 387
....
^C
12 packets captured
14 packets received by filter
0 packets dropped by kernel


But if I snoop the same on the RHEL6.4 server running DHCP server and OVM, no request can be seen:


[root@bluestone Desktop]# tcpdump -i any -n udp dst portrange 67-68
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on any, link-type LINUX_SLL (Linux cooked), capture size 65535 bytes
^C
0 packets captured
0 packets received by filter
0 packets dropped by kernel

OVS(sapphire) and OVM(bluestone) are located in the same subnet:

[root@bluestone network-scripts]# ifconfig -a
eth0      Link encap:Ethernet  HWaddr 00:14:22:72:7C:27 
          inet addr:192.168.2.48  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::214:22ff:fe72:7c27/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:106795 errors:0 dropped:0 overruns:0 frame:0
          TX packets:122056 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:59173975 (56.4 MiB)  TX bytes:25362955 (24.1 MiB)

[root@sapphire ~]# ifconfig -a
10049df2fc Link encap:Ethernet  HWaddr 8A:C5:05:83:AF:C9 
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:80 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:33200 (32.4 KiB)  TX bytes:0 (0.0 b)

eth0      Link encap:Ethernet  HWaddr 00:1A:64:64:DA:64 
          inet addr:192.168.2.202  Bcast:192.168.2.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:37664 errors:0 dropped:0 overruns:0 frame:0
          TX packets:38939 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:4537897 (4.3 MiB)  TX bytes:23127790 (22.0 MiB)

eth0:0    Link encap:Ethernet  HWaddr 00:1A:64:64:DA:64 
          inet addr:192.168.2.212  Bcast:192.168.2.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

[root@sapphire ~]# brctl show
bridge name    bridge id        STP enabled    interfaces
10049df2fc        8000.8ac50583afc9    yes        tap7.0
                            tap7.1
                            vif7.0
                            vif7.1

I turned off iptables and SELinux on the DHCP server, the issue still remained.
Any help will be highly appriciaited.

Thanks in advance,

Alex

This post has been answered by WadhahDaouehi on Aug 18 2013
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