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  • The isolated port(I-port) in private vlan concept fit prefect for our requirement. Basically we just need to make every user VM connect to I-port of the switch(vswitch or open vswitch), every dhcp server connect to P-port of the switch, then it would be enough for isolation and communication.
  • But open Open vswitch(used by XenServer and KVM) doesn't have PVLAN support. vSwitch(for VMware) support it by default.
  • So we need extra effort to simulate PVLAN on open vswitch(ovs) for Xen and KVM.
    • We would modify flow table, to:
    • 1. For every traffic leave user VM, tagged with secondary isolate vlan tag.
    • 2. Allow secondary isolated vlan tagged traffic reach DHCP server, by change the vlan tag to primary vlan tag.
    • 3. The gateway should know nothing about PVLAN, and the switch connect to the gateway should translate all the secondary vlan to primary vlan for communicating with gateway.

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Architecture and Design description

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OVS

  • For OVS, flow table need following modifications:
    • 1. For each VM:
        Outgoing tag with pvlan:
          • <a> Tagged isolated vlan and go through flow-table again(for DHCP server specify handling):
            • priority=50,dl_vlan=0xffff,dl_src=
        <VM MAC>
            • $vm_mac,actions=mod_vlan_vid:
        <secondary isolated vlan>,output:<trunk port>
        2. For each VM in the same host as DHCP server:
        <a> Allow communitcation with DHCP server(e.g. DNS): priority=100,dl_src=<VM MAC>,dl_dst=<DHCP MAC> actions=NORMAL
        <b> Allow DHCP request: priority=60,udp,dl_src=<VM MAC>,nw_dst=255.255.255.255,tp_dst=67 actions=NORMAL
        3
            • $sec_iso_vlan,resubmit:$trunk_port
          • <b> If there is no other process in the flow table, then output to trunk port:
            • priority=60,dl_vlan=$sec_iso_vlan,dl_src=$vm_mac,actions=output:$trunk_port
        • 2. For each host has DHCP server:
          • <a> ARP for DHCP server from
        outside
          • other hosts:
            • priority=
        160
            • 200,arp,dl_vlan=
        <secondary isolated vlan>
            • $sec_iso_vlan,nw_dst=
        <DHCP IP>
            • $dhcp_ip,actions=
        mod
            • strip_vlan
        _vid:<primary vlan>,NORMAL
        <b> ARP for DHCP server: priority=150,arp,nw_dst=<DHCP IP> actions=NORMAL
        <c>
            • ,output:$dhcp_port
          • <b> Accept packets from outside(e.g. DNS):
            • priority=
        100
            • 150,dl_vlan=
        <secondary isolated vlan>
            • $sec_iso_vlan,dl_dst=
        <DHCP MAC>
            • $dhcp_mac,actions=
        mod
            • strip_vlan
        _vid:<primary vlan>,NORMAL
        <d>
            • ,output:$dhcp_port
          • <c> Accept DHCP request from
        outside
          • other hosts:
            • priority=
        60
            • 100,udp,dl_vlan=
        <secondary isolated vlan>
            • $sec_iso_vlan,nw_dst=255.255.255.255,tp_dst=67,actions=
        mod
            • strip_vlan
        _vid:<primary vlan>,NORMAL
            • ,output:$dhcp_port
      • The VM migration and host restart would affect the rules, need to be reprogrammed.

      VMWare

      VMWare has two solutions that support distributed L2 routing that transparently plumb L2 switchports and associate them with vNICs of a VM, and maintain near real time state information of the network statistics on the vNICs -

      1. VMWare vNetwork Distributed Switch (vDS)
      2. Cisco Nexus 1000v (N1KV)

      Both are L2 soft switches that have a management plane and a data plane. In vDS, the management plane is called the vDS, while the data plane is the vSS or vNetwork Standard Switch. The vSS is a superset of the standard local vSwitch on each ESX host that the vDS manages. In the N1KV, the management plane is called the VSM (Virtual Supervisor Module)(switch supervisor) and the the data plane is the VEM (Virtual Ethernet Module)(switch linecards), again a superset of the standard ESX local vSwitch.

      In VMWare, a network is essentially represented by a network PortGroup. In Cisco terminology, the same is called a PortProfile. As the names indicate, a PortGroup is a group of switch ports that share the same properties, and similarly a PortProfile is the "profile" or set of properties of a switch port, and the same port profile can be applied on multiple switch ports.

      Examples of properties are VLAN IDs, ACLs, network throttle rate, PVLAN IDs, type of switchport (trunk/access) and so on.

      Thus, essentially, provisioning PVLANs on VMWare clusters involves creating portgroups/portprofiles and associating them with switchports on the vDS or the VSM and then associating vNICs on VMs with the appropriate port profile. prepareNetwork() and createPortProfile() functionality in HypervisorHostHelper will be modified accordingly.

      Switch configuration

      • Though CloudStack didn't control switch, the switches must support Private VLAN in order to get the whole setup work. This would require certain Cisco Catalyst switches.
        • It's likely we would need Catalyst 4500 series for PVLAN promiscuous trunk support.
      • The topological of switch and router would be:
        • All L2 switch(which are aware of PVLAN) connected to each other, and one of them(and only one of them) connect to router.
        • All the ports connected to the host would be configured in trunk mode, allow mgmt vlan, primary vlan(public vlan) and secondary isolated vlan.
        • The switch port connect to the router would be configured in PVLAN promiscuous trunk mode, which would translate secondary isolated vlan to primary vlan for router(which doesn't have knowledge of PVLAN).
        • If your Catalyst switch support PVLAN but not PVLAN promiscuous trunk mode(AFAIK, only Catalyst 4500 series support the mode), you need:
          • 1. Configure one of switch port as trunk for mgmt network(mgmt vlan)
          • 2. For each PVLAN, connect one port of Catalyst switch to upper switch, set the port in Catalyst Switch in promiscuous mode for one pair of PVLAN, set the port in upper switch to "access" mode, only allow traffic of primary vlan of the PVLAN pair.

      ...

      PVLAN can be enabled on shared networks. Shared networks are created by admin users, end user vms are allowed to have nics on shared networks.
      Modify createNetworkCmd (for shared networks)

      • Add a new parameter: secondary_isolated_vlanisolatedpvlan:
        • Not a required paramter. if the parameter is not null, then PVLAN would be enabled.
        • When the parameter is set, it must be advance shared network.

      DB changes

      Cisco Nexus 1000v specific changes

      New functions to add primary and secondary VLANs to port groups, and to be called in HypervisorHostHelper.java, will need to be added to VsmCommand.java and NetconfHelper.java.

      Phased implementation for VMware

      For VMware, the project will be carried out in two phases. In phase 1, pvlan support will be implemented in cloudstack for VMware Distributed Virtual Switch configurations. In phase 2, pvlan support will be implemented for provisioning profiles on Cisco Nexus 1000v.

      UI flow

      • The admin creates a shared vlan. She is asked if it is a PVLAN. If yes, in addition to the primary vlan id, she is asked for the secondary vlan id.
        The pre-confirmation dialog asks her to make sure her physical infrastructure is configured in the same fashion.

      ...