neutron

DHCP requests arrives at the dhcp interface but no offer goes back

Asked by Endre Karlson

I have 1 node that's a combined controller and compute (cmp01) and 1 other that's compute only (cmp02).

On the controller when I dump on the DHCP interface I get while starting dhclient on the VM:
root@cmp01:~# tcpdump -n -e -ttt -vvv -i tap8adb92d6-37
tcpdump: listening on tap8adb92d6-37, link-type EN10MB (Ethernet), capture size 65535 bytes
00:00:00.000000 fa:16:3e:63:12:d0 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from fa:16:3e:63:12:d0, length 300, xid 0xa387b426, secs 25, Flags [none] (0x0000)
          Client-Ethernet-Address fa:16:3e:63:12:d0
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            Parameter-Request Option 55, length 17:
              Subnet-Mask, BR, Time-Zone, Classless-Static-Route
              Domain-Name, Domain-Name-Server, Hostname, YD
              YS, NTP, MTU, Option 119
              Default-Gateway, Classless-Static-Route, Classless-Static-Route-Microsoft, Option 252
              NTP
            END Option 255, length 0
            PAD Option 0, length 0, occurs 37
00:00:00.000186 fa:16:3e:31:b4:ae > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 172.16.60.3 tell 172.16.60.1, length 28
00:00:00.999291 fa:16:3e:31:b4:ae > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 172.16.60.3 tell 172.16.60.1, length 28
00:00:00.999976 fa:16:3e:31:b4:ae > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 172.16.60.3 tell 172.16.60.1, length 28
00:00:00.877279 fa:16:3e:63:12:d0 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from fa:16:3e:63:12:d0, length 300, xid 0xf96c2974, Flags [none] (0x0000)
          Client-Ethernet-Address fa:16:3e:63:12:d0
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            Parameter-Request Option 55, length 13:
              Subnet-Mask, BR, Time-Zone, Classless-Static-Route
              Domain-Name, Domain-Name-Server, Hostname, YD
              YS, NTP, MTU, Option 119
              Default-Gateway
            END Option 255, length 0
            PAD Option 0, length 0, occurs 41
00:00:02.658845 fa:16:3e:63:12:d0 > 33:33:00:00:00:16, ethertype IPv6 (0x86dd), length 110: (hlim 1, next-header Options (0) payload length: 56) :: > ff02::16: HBH (rtalert: 0x0000) (padn)[icmp6 sum ok] ICMP6, multicast listener report v2, 2 group record(s) [gaddr ff02::1:ff63:12d0 to_ex { }] [gaddr ff02::202 to_ex { }]
00:00:00.020400 fa:16:3e:63:12:d0 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from fa:16:3e:63:12:d0, length 300, xid 0x73635337, Flags [none] (0x0000)
          Client-Ethernet-Address fa:16:3e:63:12:d0
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            Parameter-Request Option 55, length 17:
              Subnet-Mask, BR, Time-Zone, Classless-Static-Route
              Domain-Name, Domain-Name-Server, Hostname, YD
              YS, NTP, MTU, Option 119
              Default-Gateway, Classless-Static-Route, Classless-Static-Route-Microsoft, Option 252
              NTP
            END Option 255, length 0
            PAD Option 0, length 0, occurs 37
00:00:00.000182 fa:16:3e:31:b4:ae > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 172.16.60.3 tell 172.16.60.1, length 28
00:00:00.070449 fa:16:3e:63:12:d0 > 33:33:ff:63:12:d0, ethertype IPv6 (0x86dd), length 78: (hlim 255, next-header ICMPv6 (58) payload length: 24) :: > ff02::1:ff63:12d0: [icmp6 sum ok] ICMP6, neighbor solicitation, length 24, who has fe80::f816:3eff:fe63:12d0
00:00:00.928892 fa:16:3e:31:b4:ae > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 172.16.60.3 tell 172.16.60.1, length 28
00:00:01.000010 fa:16:3e:31:b4:ae > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Ethernet (len 6), IPv4 (len 4), Request who-has 172.16.60.3 tell 172.16.60.1, length 28
^C
11 packets captured
11 packets received by filter
0 packets dropped by kernel

On the Compute Node:
root@cmp02:~# tcpdump -n -e -ttt -vvv -i vnet0
tcpdump: WARNING: vnet0: no IPv4 address assigned
tcpdump: listening on vnet0, link-type EN10MB (Ethernet), capture size 65535 bytes
00:00:00.000000 fa:16:3e:63:12:d0 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from fa:16:3e:63:12:d0, length 300, xid 0xa387b426, secs 25, Flags [none] (0x0000)
          Client-Ethernet-Address fa:16:3e:63:12:d0
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            Parameter-Request Option 55, length 17:
              Subnet-Mask, BR, Time-Zone, Classless-Static-Route
              Domain-Name, Domain-Name-Server, Hostname, YD
              YS, NTP, MTU, Option 119
              Default-Gateway, Classless-Static-Route, Classless-Static-Route-Microsoft, Option 252
              NTP
            END Option 255, length 0
            PAD Option 0, length 0, occurs 37
00:00:00.000045 fa:16:3e:63:12:d0 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from fa:16:3e:63:12:d0, length 300, xid 0xa387b426, secs 25, Flags [none] (0x0000)
          Client-Ethernet-Address fa:16:3e:63:12:d0
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            Parameter-Request Option 55, length 17:
              Subnet-Mask, BR, Time-Zone, Classless-Static-Route
              Domain-Name, Domain-Name-Server, Hostname, YD
              YS, NTP, MTU, Option 119
              Default-Gateway, Classless-Static-Route, Classless-Static-Route-Microsoft, Option 252
              NTP
            END Option 255, length 0
            PAD Option 0, length 0, occurs 37

In the syslog I can see that:
Oct 12 11:02:27 cmp01 dnsmasq-dhcp[61988]: DHCPDISCOVER(tap8adb92d6-37) fa:16:3e:63:12:d0
Oct 12 11:02:27 cmp01 dnsmasq-dhcp[61988]: DHCPOFFER(tap8adb92d6-37) 172.16.60.3 fa:16:3e:63:12:d0
Oct 12 11:02:29 cmp01 dnsmasq-dhcp[61988]: DHCPDISCOVER(tap8adb92d6-37) fa:16:3e:63:12:d0
Oct 12 11:02:29 cmp01 dnsmasq-dhcp[61988]: DHCPOFFER(tap8adb92d6-37) 172.16.60.3 fa:16:3e:63:12:d0
Oct 12 11:02:36 cmp01 dnsmasq-dhcp[61988]: DHCPDISCOVER(tap8adb92d6-37) fa:16:3e:63:12:d0
Oct 12 11:02:36 cmp01 dnsmasq-dhcp[61988]: DHCPOFFER(tap8adb92d6-37) 172.16.60.3 fa:16:3e:63:12:d0
Oct 12 11:02:39 cmp01 dnsmasq-dhcp[61988]: DHCPDISCOVER(tap8adb92d6-37) fa:16:3e:63:12:d0
Oct 12 11:02:39 cmp01 dnsmasq-dhcp[61988]: DHCPOFFER(tap8adb92d6-37) 172.16.60.3 fa:16:3e:63:12:d0

It's offering each time there comes a DHCPDISCOVER in but no DHCPOFFER is leaving the interface?

I had it working in a while but after a reboot it's broken again.

# A paste of ofctl etc.
http://paste.ubuntu.com/1274581/

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Revision history for this message
dan wendlandt (danwent) said : 		#1

this is unlikely to be related to OVS, given that tcpdump says the DHCPOFFER does not even get sent out by the tap8adb92d6-37 device. The problem is probably higher up in how dnsmasq is being used.

Are you using namespaces for DHCP or not? If not, its possible that your system could have overlapping routes for the 172.16.60.0/24 prefix, causing that packet to be sent out an interface other than tap8adb92d6-37.

Revision history for this message
Zhi Yan Liu (lzy-dev) said : 		#2

I have meet this same issue, and resolved by update dnsmasq.

http://osdir.com/ml/openstack-cloud-computing/2012-05/msg00785.html
https://lists.launchpad.net/openstack/msg13221.html

Revision history for this message
Zhi Yan Liu (lzy-dev) said : 		#3

I have update it, rhel 6.3 built-in version, from:
Dnsmasq version 2.48 Copyright (C) 2000-2009 Simon Kelley
Compile time options IPv6 GNU-getopt DBus no-I18N DHCP TFTP
upgrade to:
Dnsmasq version 2.63rc6 Copyright (c) 2000-2012 Simon Kelley
Compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP DHCPv6 no-Lua TFTP no-conntrack

Revision history for this message
Graham Hemingway (graham-hemingway) said : 		#4

Endre,

It seems I have the exact same problem (https://answers.launchpad.net/quantum/+question/212874). Were you able to fix it?

Thanks,
   Graham

Revision history for this message
WcMinor (risingofthemoon) said : 		#5

Hi there,

I'm also experiencing the same problem, any update on it?

I will try to debug it.

Revision history for this message
WcMinor (risingofthemoon) said : 		#6

Ok, I managed to make it work.

In my case the interface in which the dhcpoffers where dropped in was surprisingly down.

So this made my trick:

ifconfig tapdd406286-2f up

I noticed that I was not receiving anything related to dhcpoffers on the data physical ethernet device, they were appearing just in the syslog.

Revision history for this message
WcMinor (risingofthemoon) said : 		#7

Ok, I managed to make it work.

In my case the interface in which the dhcpoffers where dropped in was
surprisingly down.

So this made my trick:

ifconfig tapdd406286-2f up

I noticed that I was not receiving anything related to dhcpoffers on the
data physical ethernet device, they were appearing just in the syslog.

On 18 February 2013 14:15, WcMinor <email address hidden>wrote:

> Question #211021 on quantum changed:
> https://answers.launchpad.net/quantum/+question/211021
>
> WcMinor requested more information:
> Hi there,
>
> I'm also experiencing the same problem, any update on it?
>
> I will try to debug it.
>
> --
> You received this question notification because you are a direct
> subscriber of the question.
>

Revision history for this message
Jaspreet Singh (jaspreets652) said : 		#8

Check Out topic relates to DHCP:

https://www.networkingsignal.com/dhcp-relay-agent-detailed-explanation/
https://www.networkingsignal.com/dhcp-and-dns/
https://www.networkingsignal.com/dhcp-snooping/
https://www.networkingsignal.com/dhcp-dora-process/

Can you help with this problem?

Provide an answer of your own, or ask Endre Karlson for more information if necessary.

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