Segmentation of ENUM Zones
The Oracle Communications Unified Session Manager supports operations with an ENUM root server, from which it can obtain partition delegation information and dynamically reach delegated authoritative ENUM servers for access information by ENUM zone. Obtaining this information is dynamic and supports query re-direction to other relevant authoritative servers the Oracle Communications Unified Session Manager may learn from the root server. This configuration applies only to DDNS-based registration deployments. The user configures the ddns-ns-caching option to enable the Oracle Communications Unified Session Manager for dynamically learned ENUM server caching.
For DDNS queries, the Oracle Communications Unified Session Manager uses a manually-configured ENUM server configuration to reach a DNS root server. The root server can respond with the authoritative name server that manages the zone. The Oracle Communications Unified Session Manager establishes dynamic entries in its ENUM server cache, with detail about the zones those servers service. This allows it to issue subsequent lookup queries directly to the correct server based on a match between telephone number and zone prefixes.
This feature assumes ENUM servers that are bind 8.0 compliant and return authority sections compliant with RFC 1304, section 4.3.2.
Additional operational details include:
- Resolution lookups are longest match, providing the Oracle Communications Unified Session Manager with the ability to send a query to authoritative servers servicing zones and sub-zones.
- Dynamic server timeouts are equal to the TTL values received in the name server's resource record, provided in the NS response. The Oracle Communications Unified Session Manager removes dynamic servers, as well as any associated ACL entries upon timeout.
- Redundancy for DDNS name server lookups is round-robin, triggered by standard DNS query timeout procedures, and following the order the system learns servers for the target zone.
- If a dynamic server fails to respond to a DDNS lookup, the Oracle Communications Unified Session Manager removes that server from the lookup list. If there are no further servers in the list, the Oracle Communications Unified Session Manager sends a 404 back to the station that originated the request. The Oracle Communications Unified Session Manager then starts any subsequent lookups for that zone by querying the root server.
- Multiple NS records are supported. The Oracle Communications Unified Session Manager creates NS records for the same zones in the order provided to it to establish name server redundancy.
- Should the Oracle Communications Unified Session Manager need to obtain a resolution for a prefix that is unknown, the Oracle Communications Unified Session Manager queries the original root server again.
- The Oracle Communications Unified Session Manager removes any dynamically-learned name server from a query list when any query fails. That server is only added back to a list when it is dynamically re-learned.
- Should the root server become unavailable, the Oracle Communications Unified Session Manager sends applicable queries to the next server in your manually-configured ENUM list.
- The Oracle Communications Unified Session Manager does not execute its configurable health-query check processes with dynamically learned name servers.
- With respect to high availability deployments, the server list is not maintained on a standby Oracle Communications Unified Session Manager. The ENUM configuration, however, is maintained on the standby via configuration synchronization. In the event of a failover, the standby Oracle Communications Unified Session Manager learns all ENUM servers using the root server as a starting point.
- This ddns-ns-caching function interoperates with the Oracle Communications Unified Session Manager's alphanumeric user name function. The zone match is done on the 3-bit checksum of the alpha-numberic user.
Note:
Name server records must present the Oracle Communications Unified Session Manager with IP addresses for the server. Name server records using FQDNs are not supported.
Obtaining Information about Dynamic ENUM Servers
The Oracle Communications Unified Session Manager provides ACLI commands that display real-time information about ENUM server interaction, including dynamically learned servers. The show enum command includes a section of statistics on cached entries
ORACLE# show enum stats localenum
Parameter-> localenum lastArg 3 enumStatsType 0
SIP ENUM Statistics:
16:01:51-48
ENUM Agent localenum
-- Period -- -------- Lifetime --------
Active High Total Total PerMax High
Queries - - 3 3 3 -
Successful - - 3 3 3 -
NotFound - - 0 0 0 -
TimedOut - - 0 0 0 -
Bad Status - - 3 3 3 -
Other Failures - - 0 0 0 -
Transactions 0 1 4 4 4 1
Cache Hits
Successful - - 0 0 0 -
NotFound - - 0 0 0 -
Cache Entries
Successful 0 0 0 0 0 0
NotFound 0 0 0 0 0 0
DropdCacheEntries - - 0 0 0 -When appended with the cache-console argument, show enum displays detailed information about dynamic server configuration and status.
ORACLE# show enum status all cache-console
Showing 2 Enum Agents: state=Active cache
---------------------------------------
Enum Agent: localenum
Realm: net192.4
EnumServers: 192.168.53.199
Query Timeout: 11
Lookup Length: 3
Health Query: '' every 0 sec
Failover To:
IncludeSrcInfo: disabled
Options:
RecursiveQuery: disabled
DNS Agent: EnumAgent[0x3b75a628(3)] ENUM w/o-stats
Domain: bogus.gy
Local Address: [256:0]192.168.53.170
Service Types: E2U+sip sip+E2U
Trans ID: 7
Cache Size: 0(0) inact-tmr=0 cache-addl=no
Max Resp Size: 512
Query Method: hunt
servers:
1=[256:0]192.168.53.199:53 OK
dynamic servers:
1=[256:0]192.168.53.205:53 OK