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Architecture and Design description

OVS

• For OVS, flow table need following modifications:
  1. For each VM:
  Outgoing tag with pvlan: priority=50,dl_src=<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. For each host has DHCP server:
  <a> ARP for DHCP server from outside: priority=160,arp,dl_vlan=<secondary isolated vlan>, nw_dst=<DHCP IP> actions=mod_vlan_vid:<primary vlan>,NORMAL
  <b> ARP for DHCP server: priority=150,arp,nw_dst=<DHCP IP> actions=NORMAL
  <c> Accept packets from outside(e.g. DNS): priority=100,dl_vlan=<secondary isolated vlan>,dl_dst=<DHCP MAC> actions=mod_vlan_vid:<primary vlan>,NORMAL
  <d> Accept DHCP request from outside: priority=60,udp,dl_vlan=<secondary isolated vlan>,nw_dst=255.255.255.255,tp_dst=67 actions=mod_vlan_vid:<primary vlan>,NORMAL
• The VM migration and host restart would affect the rules, need to be reprogrammed.

VMWare support for PVLANs

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.

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.

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