Support of DHCPV4 & Client and Server

[SuryyaKrJana]

https://redocly.github.io/redoc/?url=https://raw.githubusercontent.com/open-traffic-generator/models/dhcp_support_pr/artifacts/openapi.yaml&nocors

_This model is designed to take care of following implementation: _
1. DHCP Client & Server are Keysight and Relay Agent as DUT:
In this the construct dhcp_v4interfaces and dhcp_v4interfaces are exposed under an Ethernet Interface to configure DHCP Client parameters. The configuration of a DHCP client is placed under Ethernet Interface as parallel to IP configuration as protocol like BGP can be configured referring an IP interface or a DHCP interface.
2. DHCP Client Behind the Relay Agent and are Keysight and DHCP Server as Keysight/DUT:
In this case DHCP client sits beside the Relay Agent that runs on top of connection Interfaces.
Hence new in chained_ethernet_name connection type in Connection under Ethernets Interface under the Device. This chained Ethernet can be linked to another chained Ethernet or a connected Ethernet interface.
dhcp_v4interface and dhcp_v4interface are exposed under a Chained Ethernet interface to configure DHCP Client parameters.
3. BGP peer can be configured on top of DHCP interface:
BGP peer is to refer ipv4_name or ipv6_name for IPv4/IPv6 connected or loopback interfaces. Now BGP peer can also refer to dhcp_v4interface or dhcp_v6interface interfaces.

_Please note that DHCPv6 Client & Server and V4/V6 Relay-Agent are just place holders to show position of these when will come into implementation. _

`
// Case-1: DHCP Client & Server are Keysight and Relay Agent as DUT.
// DHCPV4-Client(x.x.x.x)<-------> (1.1.1.1)RelayAgent(DUT)(2.2.2.1) <------>(2.2.2.2) DHCPV4-Server(Pool: 100.1.1.1)
// DHCP Client is configured on connected interface.

```

config := gosnappi.NewConfig()
// add ports
p1 := config.Ports().Add().SetName("p1").SetLocation(opts.IxiaCPorts()[0])
p2 := config.Ports().Add().SetName("p2").SetLocation(opts.IxiaCPorts()[1])

// add devices
d1 := config.Devices().Add().SetName("p1d1")
d2 := config.Devices().Add().SetName("p2d1")

// add protocol stacks for device d1
d1Eth1 := d1.Ethernets().
	Add().
	SetName("p1d1eth").
	SetMac("00:00:01:01:01:01").
	SetMtu(1500)
d1Eth1.Connection().SetPortName(p1.Name())

p1d1DhcpV4Client := d1Eth1.
	DhcpV4interfacea().Add().
	SetName("p1d1dhcpv4").
	SetEthName(d1Eth1.Name())

// add protocol stacks for device d2
d2Eth1 := d2.Ethernets().
	Add().
	SetName("p2d1eth").
	SetMac("00:00:02:02:02:02").
	SetMtu(1500)
d2Eth1.Connection().SetPortName(p2.Name())

d2p2Ipv4 := d2Eth1.
	Ipv4Addresses().
	Add().
	SetName("p2d1ipv4").
	SetAddress("2.2.2.2").
	SetGateway("2.2.2.1").
	SetPrefix(32)

d2p2DhcpServerv4Iface1 := d2.DhcpServer().V4Server().
	Ipv4Interfaces().Add().
	SetIpv4Name("p2d1ipv4") //

p2d2DhcpV4Server := d2Dhcpv4Iface1.
	v4().
	SetName("p2d2DhcpV4Server")

p2d2DhcpV4Server.SetLeaseTime(1000).
	SetPoolSize(100).
	SetStartPoolAddress("100.1.1.1").
	SetPrefix(24).
	SetStep(1)

// Case-2: DHCP Client Behind the Relay Agent and are Keysight and DHCP Server as Keysight/DUT.
// DHCPV4-Client(x.x.x.x)<------->(100.1.1.1)RelayAgent(DUT)(2.2.2.1) <------>(2.2.2.2) DHCPV4-Server(Pool: 100.1.1.1)
// DHCP Client is configured on unconnected connected interface.

	```
config := gosnappi.NewConfig()

	// add ports
	p1 := config.Ports().Add().SetName("p1").SetLocation(opts.IxiaCPorts()[0])
	p2 := config.Ports().Add().SetName("p2").SetLocation(opts.IxiaCPorts()[1])

	// add devices
	d1 := config.Devices().Add().SetName("p1d1")
	d1_chained := config.Devices().Add().SetName("p1d1_chained")

	d2 := config.Devices().Add().SetName("p2d1")

	// add protocol stacks for device d1 where Relay Agent will be configureds
	d1Eth1 := d1.Ethernets().
		Add().
		SetName("p1d1eth").
		SetMac("00:00:01:01:01:01").
		SetMtu(1500)
	d1Eth1.Connection().SetPortName(p1.Name())

// Configure a IPv4 stack
	d1p1Ipv4 := d1Eth1.
		Ipv4Addresses().
		Add().
		SetName("p1d1ipv4").
		SetAddress("2.2.2.1").
		SetGateway("2.2.2.2").
		SetPrefix(24)

	// Configure a (place holder) Relay Agent
	d1p1RelayAgent := d2.RelayAgent()
	  IpV4interfaces().Add().V4RAInst().
		SetName("d1p1RelayAgent1").
		SetIpv4Name(d1p1Ipv4.Name()).
		SetCliendSideAddress("100.1.1.1")
		SetDhcpServer("2.2.2.2")

 // Chained Ethernet where DHCPClient behind the Relay Agent will be configured.
	d1ChainedEth2 := d1.Ethernets().
		Add().
		SetName("p1d1eth2_chained").
		SetMac("00:00:01:01:01:01").
	d1Eth1.Connection().SetChainedEthernetName(d1Eth1.Name())

	p1d1DhcpV4Client := d1ChainedEth2.
		DhcpV4interfaces().Add()
		SetName("p1d1dhcpv4")
	
	// add protocol stacks for device d2
	d2Eth1 := d2.Ethernets().
		Add().
		SetName("p2d1eth").
		SetMac("00:00:02:02:02:02").
		SetMtu(1500)

	d2Eth1.Connection().SetPortName(p2.Name())

	d2p2Ipv4 := d2Eth1.
		Ipv4Addresses().
		Add().
		SetName("p2d1ipv4").
		SetAddress("2.2.2.2").
		SetGateway("2.2.2.1").
		SetPrefix(24)

	d2p2DhcpServerv4Iface1 := d2.DhcpServer().V4Server().
		Ipv4Interfaces().Add().
		SetIpv4Name("p2d1ipv4") //

	p2d2DhcpV4Server := d2Dhcpv4Iface1.
		v4().
		SetName("p2d2DhcpV4Server")

	p2d2DhcpV4Server.SetLeaseTime(1000).
		SetPoolSize(100).
		SetStartPoolAddress("100.1.1.2").
		SetPrefix(24).
		SetStep(1)

//Case-3: BGP over DHCP Client on Port 1 & DHCP Server and BGP peer (over loopback)on Port2.
   ```

config := gosnappi.NewConfig()

// add ports
p1 := config.Ports().Add().SetName("p1").SetLocation(opts.IxiaCPorts()[0])
p2 := config.Ports().Add().SetName("p2").SetLocation(opts.IxiaCPorts()[1])

// add devices
d1 := config.Devices().Add().SetName("p1d1")
d2 := config.Devices().Add().SetName("p2d1")
p2Chained1 := config.Devices().Add().SetName("p2_chained1")

// add protocol stacks for device d1
d1Eth1 := d1.Ethernets().
	Add().
	SetName("p1d1eth").
	SetMac("00:00:01:01:01:01").
	SetMtu(1500)

d1Eth1.Connection().SetPortName(p1.Name())

p1d1DhcpV4Client := d1Eth1.
	DhcpV4interfaces().Add().
	SetName("p1d1dhcpv4").
	SetEthName(d1Eth1.Name())

d1Bgp := d1.Bgp().
	SetRouterId("1.1.1.2")

// Link with DHCP Client name
d1BgpIpv4Interface1 := d1Bgp.
	Ipv4Interfaces().Add().
	SetIpv4Name(p1d1DhcpV4Client.Name())

d1BgpIpv4Interface1Peer1 := d1BgpIpv4Interface1.
	Peers().
	Add().
	SetAsNumber(2222).
	SetAsType(gosnappi.BgpV4PeerAsType.EBGP).
	SetPeerAddress("22.22.22.1").
	SetName("p1d1bgpv4")

d1BgpIpv4Interface1Peer1V4Route1 := d1BgpIpv4Interface1Peer1.
	V4Routes().
	Add().
	SetNextHopIpv4Address("1.1.1.2").
	SetName("p1d1peer1rrv4").
	SetNextHopAddressType(gosnappi.BgpV4RouteRangeNextHopAddressType.IPV4).
	SetNextHopMode(gosnappi.BgpV4RouteRangeNextHopMode.MANUAL)

d1BgpIpv4Interface1Peer1V4Route1.Addresses().Add().
	SetAddress("100.10.10.1").
	SetPrefix(32).
	SetCount(4).
	SetStep(1)

d1BgpIpv4Interface1Peer1V4Route1.Advanced().
	SetMultiExitDiscriminator(50).
	SetOrigin(gosnappi.BgpRouteAdvancedOrigin.EGP)

	// add protocol stacks for device d2
d2Eth1 := d2.Ethernets().
	Add().
	SetName("p2d1eth").
	SetMac("00:00:02:02:02:02").
	SetMtu(1500)

d2Eth1.Connection().SetPortName(p2.Name())

d2p2Ipv4 := d2Eth1.
	Ipv4Addresses().
	Add().
	SetName("p2d1ipv4").
	SetAddress("2.2.2.2").
	SetGateway("2.2.2.1").
	SetPrefix(32)

d2p2DhcpServerv4Iface1 := d2.DhcpServer().V4Server().
	Ipv4Interfaces().Add().
	SetIpv4Name("p2d1ipv4") //

p2d2DhcpV4Server := d2Dhcpv4Iface1.
	v4().
	SetName("p2d2DhcpV4Server")

p2d2DhcpV4Server.SetLeaseTime(1000).
	SetPoolSize(100).
	SetStartPoolAddress("21.21.21.1").
	SetPrefix(24).
SetStep(1)

// Port2 first chained device.
p2Lo1 := p2Chained1.Ipv4Loopbacks().
Add().
SetName("p2chaineddev1.v4lo1").
SetAddress("22.22.22.1").
SetEthName(d1Eth1.Name())

p2Lo1Bgp := p2Chained1.Bgp().
	SetRouterId(p2Lo1.Address())

p2Lo1BgpIpv4Interface1 := p2Lo1Bgp.
	Ipv4Interfaces().Add().
	SetIpv4Name("p2chaineddev1.v4lo1")

p2Lo1BgpIpv4Interface1Peer1 := p2Lo1BgpIpv4Interface1.
	Peers().
	Add().
	SetAsNumber(1111).
	SetAsType(gosnappi.BgpV4PeerAsType.IBGP).
	SetPeerAddress("21.21.21.1").
	SetName("p2lo1bgpv4")

p2Lo1BgpIpv4Interface1Peer1V4Route1 := p2Lo1BgpIpv4Interface1Peer1.
	V4Routes().
	Add().
	SetName("p2lo1peer1rrv4")

p2Lo1BgpRrAddr := p2Lo1BgpIpv4Interface1Peer1V4Route1.Addresses().Add().
	SetAddress("200.1.1.1").
	SetPrefix(32)

p2Lo1BgpIpv4Interface1Peer1V4Route1.Advanced().
	SetMultiExitDiscriminator(50).
	SetOrigin(gosnappi.BgpRouteAdvancedOrigin.EGP)

`

[alakendu]

Name would be DhcpServer.V4Interface which is align with BGP (Bgp.V4Interface). Also this object acts like an interface.
Same also true for Dhcpv6