The box_ops form


The box_ops form allows address management for hosts ("boxes" in the IP registration database terminology) that have more than one address, known in the trade as multi-homed hosts. For hosts with just a single address the single_ops form should be used in preference, since it is undoubtedly more convenient and fool-proof, but it fundamentally lacks the power needed to cope with multiple addresses on a single box.

The box_ops form is an alternative to the multihome_ops form. It has fewer facilities, but is more straight-forward to operate. Unlike multihome_ops, it supports IPv6 addresses as well as IPv4 addresses, and having both is becoming one of the common reasons for being multi-homed. It is the intention to merge the extra functions available in the multihome_ops form into the box_ops form as time allows.

Multi-homed hosts

A general word about hosts with multiple addresses and their representation in the DNS may be in order here. The normal arrangement is that any single piece of equipment has a single "canonical name", never mind any other names in the offing. The canonical name identifies the physical box. If you look up the canonical name in the DNS you get given a list of all the associated addresses, and if you look up any of those addresses you get back the canonical name. A multi-homed host specified with the multihome_ops form will appear thus in the DNS. In many or most instances that is a sufficient representation, and further names specific to individual interfaces are not needed. This is because routers normally sort out optimal routing irrespective of which address you actually specify.

There are two cases where additional names are required. Occasionally different sets of services, possibly overlapping, are offered on the different addresses. In this case what is needed is just additional names resolving to specific addresses, all of which still map back to the canonical name. To set this up in the database you need to use the ANAME mechanism in addition to the basic multi-home representation. Occasionally on the other hand the object of the exercise may be to make a single machine appear as two or more entirely independent machines, which as perceived across the network are completely separate, in other words true virtual hosts, each with their own separate canonical names. This case is dealt with by the VBOX mechanism. Operations on VBOXes are delegated to COs, but ANAMEs are restricted to CS registrars.

Using box_ops

The box_ops form uses a much simpler presentation format than the multhome_ops does. Entering the name of a host and using the "display" button will display all its attributes (equipment, location, etc.) in the upper section, and a selectable list of all its IPv4 and IPv6 addresses in the lower section.

Alternatively a new box can be created by entering its name and attributes and using the "create" button. At this point it will have no IP addresses - this is a legal (if unusual) situation.

Modifying the attributes of an existing box can be done by changing the relevant text boxes and then applying the "modify" button. Note that this is similar to how the single_ops form works, and quite unlike the multihome_ops form.

Previously free IP addresses of either species can be added to a box by using the "add address" button. The address can be specified explicitly, or (for IPv4 addresses only) selected from among those available by mzone and optionally lan. IP addresses can be removed from a box by selecting them from the list and using the "remove selected address" button.

A box can be deleted by using the "destroy" button, but all of its IP addresses must have been removed first. Also note that other constraints may make csue such deletipn to fail, such as CNAMEs referencing its name, or vboxes hosted on it.