ENUM Configuration

This section shows you how to configure ENUM on your Oracle® Enterprise Session Border Controller.

To configure ENUM:

In Superuser mode, type configure terminal and press Enter.
```
ORACLE# configure terminal
```
Type session-router and press Enter to access the signaling-level configuration elements.
```
ORACLE(configure)# session-router
ORACLE(session-router)#
```
Type enum-config and press Enter. The system prompt changes to let you know that you can begin configuring individual parameters.
```
ORACLE(session-router)# enum-config
ORACLE(enum-config)#
```
name—Enter a string that uniquely identifies this ENUM configuration. You use this name in other areas of the Oracle® Enterprise Session Border Controller configuration to refer to this ENUM configuration. For example, in the local policy attributes.
top-level-domain—Enter the domain extension to be used when querying the ENUM servers for this configuration. For example, e164.arpa. The query name is a concatenation of the number and the domain.

For example the number is +17813334444 and the domain is e164.arpa, the query name would be 4.4.4.4.3.3.3.1.8.7.1.e164.arpa.com.
realm-id—Enter the realm where the ENUM servers can be reached. The realm ID is used to determine on which network interface to issue the ENUM query.
enum-servers—Enter the list of ENUM servers (an ENUM server and corresponding redundant servers) to be queried. Separate each server address with a space and enclose list within parentheses.

The first server on this list is the first one to be queried. If the query times out (including retransmissions) without getting a response, the next server on the list is queried and so on.
service-type—Enter the ENUM service types you want supported in this ENUM configuration. Possible entries are E2U+sip and sip+E2U (the default), and the types outlines in RFCs 2916 and 3721.
This parameter defaults to the following service types: E2U+sip and sip+E2U.

You can enter multiple services types in the same entry, as in this example:
```
ORACLE(enum-config)# service-type E2U+sip,sip+E2U,E2U+voicemsg
```
query-method—Set the strategy the Oracle® Enterprise Session Border Controller uses to contact ENUM servers. Valid values are:
- hunt—Directs all ENUM queries toward the first configured ENUM server. If the first server is unreachable, the Oracle® Enterprise Session Border Controller directs all ENUM queries toward the next configured ENUM server, and so on.
- round-robin—Cycles all ENUM queries, sequentially, among all configured in-service ENUM servers. Query 1 will be directed to server 1, query 2 will be directed to server 2, query 3 will be directed to server 3.
timeout—Enter the total time in seconds that should elapse before a query sent to a server (and its retransmissions) will timeout. If the first query times out, the next server is queried and the same timeout is applied. This process continues until all the servers in the list have timed out or until one of the servers responds.

The retransmission of ENUM queries is controlled by three timers. These timers are derived from this timeout value and from underlying logic that the minimum allowed retransmission interval should be 250 milliseconds; and that the Oracle® Enterprise Session Border Controller should retransmit 3 times before timing out to give the server a chance to respond. The valid values are:
- Init-timer—Is the initial retransmission interval. If a response to a query is not received within this interval, the query is retransmitted. To safeguard from performance degradation, the minimum value allowed for this timer is 250 milliseconds.
- Max-timer—Is the maximum retransmission interval. The interval is doubled after every retransmission. If the resulting retransmission interval is greater than the value of max-timer, it is set to the max-timer value.
- Expire-timer—Is the query expiration timer. If a response is not received for a query and its retransmissions within this interval, the server will be considered non-responsive and the next server in the list will be tried.
  
  The following examples show different timeout values and the corresponding timers derived from them.
  
  timeout >= 3 seconds
```
Init-timer = Timeout/11
Max-Timer = 4 * Init-timer
Expire-Timer = Timeout
```
  timeout = 1 second
```
Init-Timer = 250 ms
Max-Timer = 250 ms
Expire-Timer = 1 sec
```
  timeout = 2 seconds
```
Init-Timer = 250 ms
Max-Timer = 650 ms
Expire-Timer = 2sec
```
cache-inactivity-timer—Enter the time interval in seconds after which you want cache entries created by ENUM requests deleted, if inactive for this interval. If the cache entry gets a hit, the timer restarts and the algorithm is continued until the cache entry reaches its actual time to live.

Setting this value to zero disables caching. For optimal performance, set this to one hour. Rarely used cache entries are purged and frequently used entries are retained. The default value is 3600. The valid range is:
- Minimum—0
- Maximum—999999999
lookup-length—Specify the length of the ENUM query, starting from the most significant digit. The default is 0. The valid range is:
- Minimum—1
- Maximum—255
max-response-size—Enter the maximum size in bytes for UDP datagrams in DNS NAPTR responses. This parameter takes values from 512 (default) to 65535. Although the maximum value you can set is 65535, Oracle recommends configuring values that do not exceed 4096 bytes.
health-query-number—Set this parameter to a standard ENUM NAPTR query that will consistently return a positive response from the ENUM server.
health-query-interval—Set this parameter to the number of seconds to perpetually probe ENUM servers for health.
failover-to—Set this parameter to the name of another ENUM-config which to failover to under appropriate conditions.
cache-addl-records—Set this parameter to enabled for the Oracle® Enterprise Session Border Controller to add additional records received in an ENUM query to the local DNS cache.
include-source-info—Set this parameter to enabled for the Oracle® Enterprise Session Border Controller to send source URI information to the ENUM server with any ENUM queries.
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