Hi Ben, Thanks for explanation ..... Its clear my understanding that ovsbro & eth0 are different interface on Host. a. eth0 is related with external world on host. b. ovsbro is related with Host IP ( as Host IP is assigned to it).
Regards Ashish On Fri, Oct 4, 2013 at 9:32 PM, Ben Pfaff <b...@nicira.com> wrote: > 3a. vnet0 and eth0 are in the same VLAN, so vnet0 can access the outside > world. vnet0 and ovsbr0 are in different VLANs, so vnet0 cannot > access the host IP. > > 3b. ovsbr0 and eth0 are in different VLANs, so ovsbr0 cannot access the > external world. > > On Fri, Oct 04, 2013 at 10:40:58AM +0530, ashish yadav wrote: > > I have gone through OVS FAQ , but not able to understand Scenario 3 from > > FAQ. > > So could you please help me in same ? > > > > > > Thanks & Regards > > Ashish > > > > > > On Fri, Oct 4, 2013 at 10:16 AM, Ben Pfaff <b...@nicira.com> wrote: > > > > > The results you explain in all of your scenarios are what I would > expect > > > to happen. Did you read the introduction to VLANs in the OVS FAQ? > > > > > > Q: What's a VLAN? > > > > > > A: At the simplest level, a VLAN (short for "virtual LAN") is a way to > > > partition a single switch into multiple switches. Suppose, for > > > example, that you have two groups of machines, group A and group B. > > > You want the machines in group A to be able to talk to each other, > > > and you want the machine in group B to be able to talk to each > > > other, but you don't want the machines in group A to be able to > > > talk to the machines in group B. You can do this with two > > > switches, by plugging the machines in group A into one switch and > > > the machines in group B into the other switch. > > > > > > If you only have one switch, then you can use VLANs to do the same > > > thing, by configuring the ports for machines in group A as VLAN > > > "access ports" for one VLAN and the ports for group B as "access > > > ports" for a different VLAN. The switch will only forward packets > > > between ports that are assigned to the same VLAN, so this > > > effectively subdivides your single switch into two independent > > > switches, one for each group of machines. > > > > > > So far we haven't said anything about VLAN headers. With access > > > ports, like we've described so far, no VLAN header is present in > > > the Ethernet frame. This means that the machines (or switches) > > > connected to access ports need not be aware that VLANs are > > > involved, just like in the case where we use two different physical > > > switches. > > > > > > Now suppose that you have a whole bunch of switches in your > > > network, instead of just one, and that some machines in group A are > > > connected directly to both switches 1 and 2. To allow these > > > machines to talk to each other, you could add an access port for > > > group A's VLAN to switch 1 and another to switch 2, and then > > > connect an Ethernet cable between those ports. That works fine, > > > but it doesn't scale well as the number of switches and the number > > > of VLANs increases, because you use up a lot of valuable switch > > > ports just connecting together your VLANs. > > > > > > This is where VLAN headers come in. Instead of using one cable and > > > two ports per VLAN to connect a pair of switches, we configure a > > > port on each switch as a VLAN "trunk port". Packets sent and > > > received on a trunk port carry a VLAN header that says what VLAN > > > the packet belongs to, so that only two ports total are required to > > > connect the switches, regardless of the number of VLANs in use. > > > Normally, only switches (either physical or virtual) are connected > > > to a trunk port, not individual hosts, because individual hosts > > > don't expect to see a VLAN header in the traffic that they receive. > > > > > > None of the above discussion says anything about particular VLAN > > > numbers. This is because VLAN numbers are completely arbitrary. > > > One must only ensure that a given VLAN is numbered consistently > > > throughout a network and that different VLANs are given different > > > numbers. (That said, VLAN 0 is usually synonymous with a packet > > > that has no VLAN header, and VLAN 4095 is reserved.) > > > > > > On Fri, Oct 04, 2013 at 10:12:08AM +0530, ashish yadav wrote: > > > > Hi, > > > > > > > > Could anyone please look into these fundamental queries of OVS & Vlan > > > and > > > > reply ? > > > > > > > > > > > > Thanks & Regards > > > > Ashish > > > > > > > > > > > > On Thu, Oct 3, 2013 at 9:42 PM, ashish yadav < > ashishyada...@gmail.com > > > >wrote: > > > > > > > > > Hi, > > > > > > > > > > I was doing some exercise, came across few scenario. > > > > > I need help to understand these cases. > > > > > > > > > > *Environment: * > > > > > a. One Host and one VM in it > > > > > b. OVS running: > > > > > [root@sholay ashish]# ovs-vsctl show > > > > > 2b113c03-81e5-4c90-ba6c-b2eb2381432a > > > > > Bridge "ovsbr0" > > > > > Port "ovsbr0" > > > > > Interface "ovsbr0" > > > > > type: internal > > > > > Port "vnet0" > > > > > Interface "vnet0" > > > > > Port "eth0" > > > > > Interface "eth0" > > > > > ovs_version: "1.4.6" > > > > > > > > > > VM is up and I am able to ping: > > > > > a. External World from VM & Host. > > > > > b. Ping between HOST & VM fine. > > > > > > > > > > *Scenario 1:* > > > > > vnet0 is vlan tag: > > > > > [root@sholay ashish]# ovs-vsctl show > > > > > 2b113c03-81e5-4c90-ba6c-b2eb2381432a > > > > > Bridge "ovsbr0" > > > > > Port "ovsbr0" > > > > > tag: 0 > > > > > Interface "ovsbr0" > > > > > type: internal > > > > > Port "vnet0" > > > > > tag: 5 > > > > > Interface "vnet0" > > > > > Port "eth0" > > > > > tag: 0 > > > > > Interface "eth0" > > > > > ovs_version: "1.4.6" > > > > > > > > > > a. From VM, not able to ping Host machine & External world. > > > > > b. From Host, able to ping External world. > > > > > > > > > > This is desired behaviour. No problem here. > > > > > > > > > > > > > > > *Scenario 2:* > > > > > ovsbr0 & vent0 are Vlan Tag: > > > > > [root@sholay ashish]# ovs-vsctl show > > > > > 2b113c03-81e5-4c90-ba6c-b2eb2381432a > > > > > Bridge "ovsbr0" > > > > > Port "ovsbr0" > > > > > tag: 5 > > > > > Interface "ovsbr0" > > > > > type: internal > > > > > Port "vnet0" > > > > > tag: 5 > > > > > Interface "vnet0" > > > > > Port "eth0" > > > > > tag: 0 > > > > > Interface "eth0" > > > > > ovs_version: "1.4.6" > > > > > > > > > > a. VM is able to Ping host, but Fail to ping External > world. > > > > > * Why it is so ?* > > > > > b. Host Machine Fail to ping External world. > > > > > *Why its is so ?* > > > > > > > > > > > > > > > *Scenario 3:* > > > > > eth0 & vent0 are Vlan Tag: > > > > > [root@sholay ashish]# ovs-vsctl show > > > > > 2b113c03-81e5-4c90-ba6c-b2eb2381432a > > > > > Bridge "ovsbr0" > > > > > Port "ovsbr0" > > > > > tag: 0 > > > > > Interface "ovsbr0" > > > > > type: internal > > > > > Port "vnet0" > > > > > tag: 5 > > > > > Interface "vnet0" > > > > > Port "eth0" > > > > > tag: 5 > > > > > Interface "eth0" > > > > > ovs_version: "1.4.6" > > > > > > > > > > a. VM able to ping external world, but fail to ping host ip. > > > > > * Why it is so ?* > > > > > b. Host Machine not able to ping external world. > > > > > *Why VM can excess external world, but host not ?* > > > > > > > > > > > > > > > Thanks & Regards > > > > > Ashish > > > > > > > > > > > > > > > > > _______________________________________________ > > > > discuss mailing list > > > > discuss@openvswitch.org > > > > http://openvswitch.org/mailman/listinfo/discuss > > > > > > >
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