DTC - DNS Traffic Control¶

The dtc domain covers 22 resources: the DTC core object, Load-Balanced Domain Names (LBDNs), pools, servers, topology objects and rules, six monitor types, five DTC record types, certificates, and all-records.

Access via client.dtc.

Overview¶

DNS Traffic Control (DTC) provides intelligent DNS-based load balancing and failover. The object hierarchy is:

LBDN (Load-Balanced Domain Name)
  └── Pool (group of servers with a load-balancing method)
        └── Server (individual endpoint)
              └── Monitor (health check: HTTP, ICMP, TCP, SIP, SNMP, PDP)

DTC core and topology¶

import asyncio
from ibx_nios_sdk import NiosClient

async def main():
    async with NiosClient() as client:
        # The `dtc` object itself is function-only: WAPI restricts read/create/
        # update/delete on it, so it is reached through call_function().
        state = await client.dtc.dtc.call_function(
            None, "dtc_get_object_grid_state", dtc_object="dtc:lbdn/ZG5z..."
        )
        print(state["enabled_on"], state["disabled_on"])

        # Topology objects (geographic / subnet-based routing)
        topologies = await client.dtc.topology.list().all()
        for topo in topologies:
            print(topo.name, topo.comment)

        # Topology labels and rules
        labels = await client.dtc.topology_label.list().all()
        rules = await client.dtc.topology_rule.list().all()

asyncio.run(main())

Servers¶

DTC servers represent individual backend endpoints.

async with NiosClient() as client:
    # Create a server
    server = await client.dtc.server.create({
        "name": "web-server-01",
        "host": "10.10.0.5",
        "comment": "Primary web server",
    })
    print(server._ref)

    # List servers
    servers = await client.dtc.server.list().all()
    for s in servers:
        print(s.name, s.host)

Monitors¶

Monitors perform health checks on DTC servers. Six types are available:

Resource	Protocol	Description
`dtc_monitor_http`	HTTP/HTTPS	HTTP GET/POST health check
`dtc_monitor_icmp`	ICMP	Ping-based availability check
`dtc_monitor_tcp`	TCP	Port reachability check
`dtc_monitor_sip`	SIP	VoIP endpoint health check
`dtc_monitor_snmp`	SNMP	SNMP OID value check
`dtc_monitor_pdp`	PDP	Policy Decision Point check
`dtc_monitor`	(base)	Generic monitor query

async with NiosClient() as client:
    # HTTP monitor
    http_mon = await client.dtc.monitor_http.create({
        "name": "http-check-80",
        "port": 80,
        "request": "GET / HTTP/1.1\r\nHost: example.com\r\n\r\n",
        "result": "STATUS_200",
        "comment": "Web server health check",
    })

    # ICMP monitor
    icmp_mon = await client.dtc.monitor_icmp.create({
        "name": "ping-check",
        "comment": "Basic ICMP ping",
    })

    # TCP monitor
    tcp_mon = await client.dtc.monitor_tcp.create({
        "name": "tcp-443",
        "port": 443,
        "comment": "HTTPS port reachability",
    })

Pools¶

Pools group servers and define the load-balancing algorithm.

async with NiosClient() as client:
    # Create a pool
    pool = await client.dtc.pool.create({
        "name": "web-pool",
        "lb_preferred_method": "ROUND_ROBIN",
        "servers": [
            {"server": server._ref, "ratio": 1},
        ],
        "monitors": [http_mon._ref],
        "comment": "Web server pool",
    })

    # List pools
    pools = await client.dtc.pool.list().all()
    for p in pools:
        print(p.name, p.lb_preferred_method)

LBDNs (Load-Balanced Domain Names)¶

An LBDN is the DNS name that DTC manages. When a client queries the LBDN name, DTC selects the best pool/server and returns an appropriate answer.

async with NiosClient() as client:
    # Create an LBDN
    lbdn = await client.dtc.lbdn.create({
        "name": "www",
        "zone": "example.com",
        "lb_method": "TOPOLOGY",
        "topology": topology._ref,
        "pools": [{"pool": pool._ref, "ratio": 1}],
        "comment": "Website LBDN",
        "types": ["A"],
        "persistence": 0,
    })
    print(lbdn._ref)

    # List LBDNs
    lbdns = await client.dtc.lbdn.list().all()

DTC records¶

DTC record objects represent the DNS responses that DTC returns:

Resource	DNS type
`dtc_record_a`	A
`dtc_record_aaaa`	AAAA
`dtc_record_cname`	CNAME
`dtc_record_naptr`	NAPTR
`dtc_record_srv`	SRV

async with NiosClient() as client:
    # Query all DTC records
    all_dtc_recs = await client.dtc.allrecords.list().all()
    for rec in all_dtc_recs:
        print(rec.name, rec.type)

DTC certificates¶

async with NiosClient() as client:
    certs = await client.dtc.certificate.list().all()
    for cert in certs:
        print(cert.certificate, cert.comment)