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Juniper JunosVContrail(JVC) plugin supports Neutron Core V2 APIs alongwith L3, Security Groups, VPC, IPAM and Policy extensions on a system running Juniper's Contrail based Virtual Network System. The plugin itself is stateless and transforms Neutron resource request/responses into the form required by the JVC controller. The JVContrailPlugin.py file has classes interfacing with Neutron plugin/extension classes and the config_db.py has files that deal with data transformation and talking with JVC controller.

IPAM Resource

Information common to a set of subnets on a network will be present in this resource. Following information will be stored in the resource:

  • Address allocation scheme (DHCP or unmanaged)
  • DNS server information
  • CIDR to be used by the network (in which all subnet definitions should belong)
  • List of DHCP option, value tuples

Network Policy Resource

Network policy is mechanism by which a declarative way is provided to the clients to decided how Neutron virtual networks are connected and what traffic is allowed over those connections. Clients do not have to worry about how exactly the connectivity is achieved and how/where the rules are applied. This is to simplify deployments of multitier applications

Network Policy Example

For example as application developer user wants to put web servers in network called front-end network. Appservers in network called back-end network Allocate floating ip from public network. Floating ip is assigned as VIP to web servers Only MySQL traffic is allowed from front-end to backend

This information should be enough for the network plugin to add routing between front-end and back-end and ACLs for MySQL between these two networks. Users (application developers and deployers) need not worry about routers and firewall rules etc. Basically network policy provides this declarative way for user to simplify application deployment.

In above example user creates policy called front-end-to-back-end:

  • pass front-end any <> back-end MySQL

This policy is attached to both the networks. Multiple policies can be attached to the network. Policies can be templatized with parameters as attached networks. Admin can provide precooked policy templates

Network Policy and FWaaS

Network Policy is in no way a replacement for FWaaS. In this context traditional FW is still valid. Rules provided in Network Policy are simple and limited in comparison to traditional firewall. Though they complement each other. For application deployers firewall rules and configuration might be too overwhelming. Users may have REST interface between front-end and backend. They might want to take all traffic between front-end and back-end via a firewall instance. In this case above rule changes in following way

  • pass front-end any <> back-end any any apply-service Firewall_instance_1

Network Policy and Security Groups

Network policy is not replacement for security groups either. Security groups are protecting the interfaces to VM(s). Network policy is between virtual networks. Have policies at various levels actually increases flexibility and reduces need for NxN matrix like rule explosion.

Network Policy Bind Points

In traditional networking gear ACL were always applied at various levels.

  • Ports ACL(s) à Security groups
  • VLAN ACL(s) and Router ACL(s) à network policy

Network policy can be expressed in terms of network ID(s) rather than IP prefixes (CIDRs)

Information given in such a resource can be used to derive

  • Connectivity between networks. i.e whether at a L3 network level routes need to be exchanged. e.g. allow traffic from web-network to db-network.
  • Packet filters on traffic crossing two networks. e.g. allow only mysql traffic between web-network to db-network

Network Policy Fields

A policy is composed of a set of entries which have the following fields (snort-like format):

  • direction - uni/bi-directional
  • protocol - tcp/udp/icmp/any
  • src-addresses - list in terms of subnets/networks/security-groups
  • src-ports - list of port numbers
  • dst-addresses - list in terms of subnets/networks/security-groups
  • dst-ports - list of port numbers
  • action-list - list of actions like apply-service, mirror-to, referencing an already defined service or simple actions [pass|deny|log|reject|drop|alert]