[ovs-discuss] 答复: How does OVS gre packet flow

pei Jikui jkpei at hotmail.com
Mon Jan 28 14:40:06 UTC 2019


more information, the experiment I did is,

1) at HostA,
ping 1.2.3.5 it succeeded.   tcpdump -n -e -i ens33 proto gre at hostB could capture the GRE packet.

at HostB,
ping 1.2.3.4 it succeeded.   tcpdump -n -e -i ens33 proto gre at hostA could capture the GRE packet.


While I still want to understand how the GRE packet is encapsulated one Host and then forwarded to the other Host.  How the gre1 interface's functionality is called at each host? The two bridges at each host are not connected, how the packets forwarded between the two bridges br1 and br2 at each host?

Thanks much in advance.

________________________________
发件人: pei Jikui
发送时间: 2019年1月28日 22:20
收件人: ovs-discuss at openvswitch.org
主题: How does OVS gre packet flow

hi,

1) I am experimenting the OVS GRE tunnel with the following configurations with two hosts, HOSTA and HOSTB. The  experiment succeeded while I still could not understand how the packet flows between the two hosts.

There are two bridges created by ovs-vsct at each host (br1 and br2).  These two bridges in one Host aren't even connected then how the packets are forwarded between the two bridges in one host and among the two hosts hence? And how the packets are encapsulated with the GRE header?

2) test-bed and configuration

HostA with ip 10.128.0.155
HostB with ip 10.128.0.156

At HostA:
a)Create two bridges br1 and br2

   ovs-vsctl add-br br1

   ovs-vsctl add-br br2

b)Configure br1

  ovs-vsctl add-port br1 ens33

  ip addr flush dev ens33

  ip addr add 10.128.0.155/24 dev br1

c)Configure br2

  ovs-vsctl add-port br2 gre1 -- set interface gre1 type=gre options: remote_ip=10.128.0.156

  ip addr add 1.2.3.4/24 dev br2

  ip link set dev br2 up


At HostB:

a)Create two bridges br1 and br2

   ovs-vsctl add-br br1

   ovs-vsctl add-br br2

b)Configure br1

  ovs-vsctl add-port br1 ens33

  ip addr flush dev ens33

  ip addr add 10.128.0.156/24 dev br1

c)Configure br2

  ovs-vsctl add-port br2 gre1 -- set interface gre1 type=gre options: remote_ip=10.128.0.155

  ip addr add 1.2.3.4/24 dev br2

  ip link set dev br2 up


Thanks

Jikui

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