[Openstack] can anybody help to explain how the packet of ping shoule be forwarded from vm

Sam Lee lixq2000 at gmail.com
Tue Sep 23 07:51:37 UTC 2014


I think routing is in step 4。  The packet shoule be processed by eth1 based
on routing table. in fact eth0 process it. this is what I am puzzled

2014-09-23 15:47 GMT+08:00 Sam Lee <lixq2000 at gmail.com>:

> Can you explain it more detail?  when the routing table is used?
>
> 2014-09-23 15:39 GMT+08:00 严超 <yanchao727 at gmail.com>:
>
>> I think that path should depends on your route table. You can modify
>> route table to take some tests.
>>
>> *Best Regards!*
>>
>>
>> *Chao Yan--------------**My twitter:Andy Yan @yanchao727
>> <https://twitter.com/yanchao727>*
>>
>>
>> *My Weibo:http://weibo.com/herewearenow
>> <http://weibo.com/herewearenow>--------------*
>>
>> 2014-09-23 15:21 GMT+08:00 Sam Lee <lixq2000 at gmail.com>:
>>
>>> I have tracked the packets using tcpdump, and it shows that the eth0
>>> process the packets. When a floating ip is added on instance, eth1 process
>>> the packets.
>>>
>>> 2014-09-23 15:18 GMT+08:00 严超 <yanchao727 at gmail.com>:
>>>
>>>> Yes, that's what I suggest. You can use tcpdump to track packages as
>>>> well.
>>>>
>>>> *Best Regards!*
>>>>
>>>>
>>>> *Chao Yan--------------**My twitter:Andy Yan @yanchao727
>>>> <https://twitter.com/yanchao727>*
>>>>
>>>>
>>>> *My Weibo:http://weibo.com/herewearenow
>>>> <http://weibo.com/herewearenow>--------------*
>>>>
>>>> 2014-09-23 15:13 GMT+08:00 Sam Lee <lixq2000 at gmail.com>:
>>>>
>>>>> I am not sure you are right or not.    Bridge is a virtual switch, if
>>>>> we want to communicate outside world using bridge, we must attach a
>>>>> physical devices to bridge. eth0 is just the device.
>>>>>
>>>>> 2014-09-23 15:04 GMT+08:00 严超 <yanchao727 at gmail.com>:
>>>>>
>>>>>> eth0 is virtualized as br100 , as your command show:
>>>>>>
>>>>>> 2: eth0:  mtu 1500 qdisc pfifo_fast *master br100 state UP* qlen 1000
>>>>>>     link/ether 00:1e:67:6a:8b:c9 brd ff:ff:ff:ff:ff:ff
>>>>>>     inet6 fe80::21e:67ff:fe6a:8bc9/64 scope link
>>>>>>        valid_lft forever preferred_lft forever
>>>>>>
>>>>>> So I think packages would be handled by eth0. Right?
>>>>>>
>>>>>>
>>>>>> *Best Regards!*
>>>>>>
>>>>>>
>>>>>> *Chao Yan--------------**My twitter:Andy Yan @yanchao727
>>>>>> <https://twitter.com/yanchao727>*
>>>>>>
>>>>>>
>>>>>> *My Weibo:http://weibo.com/herewearenow
>>>>>> <http://weibo.com/herewearenow>--------------*
>>>>>>
>>>>>> 2014-09-23 14:33 GMT+08:00 Sam Lee <lixq2000 at gmail.com>:
>>>>>>
>>>>>>> I set up an openstack environment using nova-network with multi_host
>>>>>>> mode.
>>>>>>>
>>>>>>> created network info as below,
>>>>>>>
>>>>>>> root at ubuntu:~# nova network-show e77b754d-5a89-41fd-8c82-69051e69c4ed
>>>>>>> +---------------------+--------------------------------------+
>>>>>>> | Property            | Value                                |
>>>>>>> +---------------------+--------------------------------------+
>>>>>>> | bridge              | br100                                |
>>>>>>> | vpn_public_port     | None                                 |
>>>>>>> | dhcp_start          | 172.16.10.202                        |
>>>>>>> | bridge_interface    | eth0                                 |
>>>>>>> | updated_at          | None                                 |
>>>>>>> | id                  | e77b754d-5a89-41fd-8c82-69051e69c4ed |
>>>>>>> | cidr_v6             | None                                 |
>>>>>>> | deleted_at          | None                                 |
>>>>>>> | gateway             | 172.16.10.1                          |
>>>>>>> | rxtx_base           | None                                 |
>>>>>>> | label               | private                              |
>>>>>>> | priority            | None                                 |
>>>>>>> | project_id          | None                                 |
>>>>>>> | vpn_private_address | None                                 |
>>>>>>> | deleted             | 0                                    |
>>>>>>> | vlan                | None                                 |
>>>>>>> | broadcast           | 172.16.10.207                        |
>>>>>>> | netmask             | 255.255.255.248                      |
>>>>>>> | injected            | False                                |
>>>>>>> | cidr                | 172.16.10.200/29                     |
>>>>>>> | vpn_public_address  | None                                 |
>>>>>>> | multi_host          | True                                 |
>>>>>>> | dns2                | None                                 |
>>>>>>> | created_at          | 2014-09-11T07:58:13.000000           |
>>>>>>> | host                | None                                 |
>>>>>>> | gateway_v6          | None                                 |
>>>>>>> | netmask_v6          | None                                 |
>>>>>>> | dns1                | 8.8.4.4                              |
>>>>>>> +---------------------+--------------------------------------+
>>>>>>> Note: 172.16.10.1 is the physical gateway
>>>>>>>
>>>>>>> route info of the host as below:
>>>>>>>
>>>>>>> Kernel IP routing table
>>>>>>> Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
>>>>>>> 0.0.0.0         172.16.10.1     0.0.0.0         UG    100    0        0 eth1
>>>>>>> 10.10.100.0     0.0.0.0         255.255.255.0   U     0      0        0 br100
>>>>>>> 172.16.10.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
>>>>>>> 172.16.10.200   0.0.0.0         255.255.255.248 U     0      0        0 br100
>>>>>>>
>>>>>>> three instances has been created as below,
>>>>>>>
>>>>>>> root at ubuntu:~# nova list
>>>>>>> +--------------------------------------+-------+--------+-----------------------+
>>>>>>> | ID                                   | Name  | Status | Networks              |
>>>>>>> +--------------------------------------+-------+--------+-----------------------+
>>>>>>> | 5867fa88-de5c-4656-9811-5c86128b786b | test3 | ACTIVE | private=172.16.10.202 |
>>>>>>> | 272f8d4f-f924-488b-855f-7f53a2372708 | test4 | ACTIVE | private=172.16.10.204 |
>>>>>>> | aec01738-996f-42dc-a921-1c859c79ffed | test5 | ACTIVE | private=172.16.10.205 |
>>>>>>> +--------------------------------------+-------+--------+-----------------------+
>>>>>>>
>>>>>>> ip info of host:
>>>>>>>
>>>>>>> root at ubuntu:~# ip a
>>>>>>> 1: lo:  mtu 16436 qdisc noqueue state UNKNOWN
>>>>>>>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>>>>>>>     inet 127.0.0.1/8 scope host lo
>>>>>>>     inet 169.254.169.254/32 scope link lo
>>>>>>>     inet6 ::1/128 scope host
>>>>>>>        valid_lft forever preferred_lft forever
>>>>>>> 2: eth0:  mtu 1500 qdisc pfifo_fast master br100 state UP qlen 1000
>>>>>>>     link/ether 00:1e:67:6a:8b:c9 brd ff:ff:ff:ff:ff:ff
>>>>>>>     inet6 fe80::21e:67ff:fe6a:8bc9/64 scope link
>>>>>>>        valid_lft forever preferred_lft forever
>>>>>>> 3: eth1:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
>>>>>>>     link/ether 00:1e:67:6a:8b:c8 brd ff:ff:ff:ff:ff:ff
>>>>>>>     inet 172.16.10.16/24 brd 172.16.10.255 scope global eth1
>>>>>>>     inet6 fe80::21e:67ff:fe6a:8bc8/64 scope link
>>>>>>>        valid_lft forever preferred_lft forever
>>>>>>> 5: br100:  mtu 1500 qdisc noqueue state UP
>>>>>>>     link/ether 00:1e:67:6a:8b:c9 brd ff:ff:ff:ff:ff:ff
>>>>>>>     inet 172.16.10.203/29 brd 172.16.10.207 scope global br100
>>>>>>>     inet 10.10.100.52/24 brd 10.10.100.255 scope global br100
>>>>>>>     inet6 fe80::44c7:b4ff:fe0c:3f/64 scope link
>>>>>>>        valid_lft forever preferred_lft forever
>>>>>>> 6: vnet0:  mtu 1500 qdisc pfifo_fast master br100 state UNKNOWN qlen 500
>>>>>>>     link/ether fe:16:3e:0f:03:49 brd ff:ff:ff:ff:ff:ff
>>>>>>>     inet6 fe80::fc16:3eff:fe0f:349/64 scope link
>>>>>>>        valid_lft forever preferred_lft forever
>>>>>>> 7: vnet1:  mtu 1500 qdisc pfifo_fast master br100 state UNKNOWN qlen 500
>>>>>>>     link/ether fe:16:3e:b3:d8:a1 brd ff:ff:ff:ff:ff:ff
>>>>>>>     inet6 fe80::fc16:3eff:feb3:d8a1/64 scope link
>>>>>>>        valid_lft forever preferred_lft forever
>>>>>>> 8: vnet2:  mtu 1500 qdisc pfifo_fast master br100 state UNKNOWN qlen 500
>>>>>>>     link/ether fe:16:3e:0e:7a:0d brd ff:ff:ff:ff:ff:ff
>>>>>>>     inet6 fe80::fc16:3eff:fe0e:7a0d/64 scope link
>>>>>>>        valid_lft forever preferred_lft forever
>>>>>>>
>>>>>>> mac table of br100:
>>>>>>>
>>>>>>> root at ubuntu:~# brctl showmacs br100
>>>>>>> port no mac addr                is local?       ageing timer
>>>>>>>   1     00:0c:29:27:9d:7e       no                16.79
>>>>>>>   1     00:0c:29:27:9d:88       no                 5.49
>>>>>>>   1     00:0c:29:58:9a:64       no                31.86
>>>>>>>   1     00:0c:29:f3:cf:7b       no                21.28
>>>>>>>   1     00:12:7f:7d:37:a1       no                35.54
>>>>>>>   1     00:14:5e:ac:7c:b5       no                26.20
>>>>>>>   1     00:14:5e:e8:03:d1       no                13.31
>>>>>>>   1     00:14:f2:a8:00:81       no                 1.11
>>>>>>>   1     00:1e:67:45:85:ad       no                14.02
>>>>>>>   1     00:1e:67:64:ed:c9       no                10.10
>>>>>>>   1     00:1e:67:64:ee:a5       no                 9.38
>>>>>>>   1     00:1e:67:6a:8b:c9       yes                0.00
>>>>>>>   1     00:1e:67:97:17:ee       no                52.97
>>>>>>>   1     52:54:00:01:40:23       no                10.72
>>>>>>>   1     52:54:00:1c:71:3d       no                 5.50
>>>>>>>   1     52:54:00:47:9c:ee       no                 8.70
>>>>>>>   1     52:54:00:b8:aa:45       no                 9.79
>>>>>>>   1     52:54:00:ee:60:44       no                 7.61
>>>>>>>   1     5c:f3:fc:00:0e:da       no                56.27
>>>>>>>   1     5c:f3:fc:00:ad:02       no                 1.13
>>>>>>>   1     6c:ae:8b:51:49:12       no                 0.64
>>>>>>>   1     8a:62:65:05:8d:02       no                 5.38
>>>>>>>   1     ae:2a:9d:74:11:03       no               155.47
>>>>>>>   1     e4:1f:13:75:47:e0       no                 8.24
>>>>>>>   1     e4:1f:13:fc:a8:21       no               176.11
>>>>>>>   1     fa:16:3e:00:c8:ce       no                 0.38
>>>>>>>   1     fa:16:3e:05:61:a3       no                 4.29
>>>>>>>   4     fa:16:3e:0e:7a:0d       no                11.35
>>>>>>>   2     fa:16:3e:0f:03:49       no                 9.90
>>>>>>>   1     fa:16:3e:2c:6c:55       no                24.90
>>>>>>>   1     fa:16:3e:2d:f0:f0       no                 7.40
>>>>>>>   1     fa:16:3e:3b:35:e1       no                27.88
>>>>>>>   1     fa:16:3e:3f:1a:0c       no                 9.18
>>>>>>>   1     fa:16:3e:49:d6:54       no                10.57
>>>>>>>   1     fa:16:3e:4a:47:6e       no                13.07
>>>>>>>   1     fa:16:3e:61:d5:0c       no                24.14
>>>>>>>   1     fa:16:3e:6b:89:c1       no                25.96
>>>>>>>   1     fa:16:3e:85:80:df       no                 3.74
>>>>>>>   1     fa:16:3e:8d:a4:da       no                28.20
>>>>>>>   1     fa:16:3e:9f:bb:0c       no                13.65
>>>>>>>   1     fa:16:3e:a6:88:1d       no                24.17
>>>>>>>   3     fa:16:3e:b3:d8:a1       no                 6.07
>>>>>>>   1     fa:16:3e:c8:42:0d       no                27.80
>>>>>>>   1     fa:16:3e:ca:a8:8e       no                 4.70
>>>>>>>   1     fa:16:3e:e8:a7:9b       no                27.31
>>>>>>>   4     fe:16:3e:0e:7a:0d       yes                0.00
>>>>>>>   2     fe:16:3e:0f:03:49       yes                0.00
>>>>>>>   3     fe:16:3e:b3:d8:a1       yes                0.00
>>>>>>>
>>>>>>> arp table of instance test5:
>>>>>>>
>>>>>>> [root at test5 ~]# arp -a
>>>>>>> ? (172.16.10.203) at 00:1e:67:6a:8b:c9 [ether] on eth0
>>>>>>> ? (172.16.10.1) at 00:12:7f:7d:37:a1 [ether] on eth0
>>>>>>>
>>>>>>> route info of instance test5
>>>>>>>
>>>>>>> [root at test5 ~]# route -n
>>>>>>> Kernel IP routing table
>>>>>>> Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
>>>>>>> 172.16.10.1     0.0.0.0         255.255.255.255 UH    0      0        0 eth0
>>>>>>> 172.16.10.200   0.0.0.0         255.255.255.248 U     1      0        0 eth0
>>>>>>> 192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0
>>>>>>> 0.0.0.0         172.16.10.1     0.0.0.0         UG    0      0        0 eth0
>>>>>>>
>>>>>>> I ping www.sina.com.cn in instances test5(172.16.10.205)
>>>>>>>
>>>>>>> [root at test5 ~]# ping www.sina.com.cn
>>>>>>> PING ara.sina.com.cn (58.63.236.35) 56(84) bytes of data.
>>>>>>> 64 bytes from 58.63.236.35: icmp_seq=1 ttl=49 time=38.4 ms
>>>>>>> 64 bytes from 58.63.236.35: icmp_seq=2 ttl=49 time=38.5 ms
>>>>>>> 64 bytes from 58.63.236.35: icmp_seq=3 ttl=49 time=38.2 ms
>>>>>>> ^C
>>>>>>> --- ara.sina.com.cn ping statistics ---
>>>>>>> 3 packets transmitted, 3 received, 0% packet loss, time 2436ms
>>>>>>> rtt min/avg/max/mdev = 38.259/38.427/38.536/0.256 ms
>>>>>>>
>>>>>>> In my option, the packet will go through as follow,
>>>>>>> 1. vm eth0
>>>>>>> 2. br100
>>>>>>> 3. according the mac table of switch br100, the packet will go
>>>>>>> through to port 1
>>>>>>>
>>>>>>> the next step has always puzzled me
>>>>>>> 4. the packet arrived at host eth0. Once the packet arrived eth0, it
>>>>>>> will be processed by iptables chains, INPUT, PREROUTING, kernel routing,
>>>>>>> OUTPUT and so on. the destination address is 58.63.236.35, based on the
>>>>>>> kernel routing table, the packet will be processed by eth1. *In
>>>>>>> fact, eth0 processes it.*can anyone explain why??
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>>>>>>>
>>>>>>> Thanks in advance.
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Mailing list:
>>>>>>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
>>>>>>> Post to     : openstack at lists.openstack.org
>>>>>>> Unsubscribe :
>>>>>>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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