1 / 17

Name Resolution in Network Management

Name Resolution in Network Management. A Quick Look at the Aspects of Naming and Name Resolution. What Is Name Resolution?. Used to translate the IP Address to a name. Provides a way of identifying resources by name rather than the address itself. The Components. /etc/hosts (Files)

lindanichols
Télécharger la présentation

Name Resolution in Network Management

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Name Resolution in Network Management A Quick Look at the Aspects of Naming and Name Resolution

  2. What Is Name Resolution? • Used to translate the IP Address to a name. • Provides a way of identifying resources by name rather than the address itself.

  3. The Components • /etc/hosts (Files) • /etc/networks (Files) • Domain Name Service (DNS) • Network Information Service (NIS) • Applications that use name resolution are dependent upon this working properly.

  4. Components of Network Node Manager Affected by Name Resolution • Maps • Discovery • Events • Tools and Applications • ECS and Correlation • SNMP Configuration

  5. What’s Legal in a Host Name? • According to RFC-1035 (STD13): • The labels must follow the rules for ARPANET host names. They must start with a letter, end with a letter or digit, and have as interior characters only letters, digits, and hyphen. There are also some restrictions on the length. Labels must be 63 characters or less. • Note that tildes, underscores,dots orpunctuation characters are not legal.

  6. DNS Names • Made up of a host name suffixed by domain and sub-domain labels separated by the dot character. • mail.southernview.com is the host mail, sub-domain southernview, within the domain of com.

  7. Network Node Manager Node Labels • 1) If the node supports IP: •   1a) If a non-migratable software loopback IP address(other than 127.0.0.1) exists on the node, and the address resolves to an IP hostname, that hostname is used. •   1b) Otherwise, NNM chooses the name associated with the lowest numbered non-migratable IP address that resolves to an IP hostname. • 1c) If no IP addresses resolve to an IP hostname, the lowest numbered non-migratable IP address is formatted as a string and used as the hostname. •   [ "lowest numbered" means when compared as integers. ] • [ "non-migratable" applies only to HP's Service Guard nodes; a migratable address is one that can migrate between systems in a Service Guard cluster. ]

  8. NNM Continued • 2) Otherwise, if the node supports IPX:  • 2a) If the node has an internal IPX server address (i.e. an address of the form <netnum>:000000000001), that address is formatted as a string and used as the hostname. • 2b) Otherwise, the lowest numbered IPX address is formatted as a string and used as the hostname.[ "lowest numbered" is determined by a byte-by-byte comparison ] •   3) Otherwise, if the node supports neither IP nor IPX, but has an LLA/MAC address, the address is formatted as a string and used as the hostname. The hostname is stored in object database's "IP Hostname" field, possibly making the name somewhat of a mis-nomer (it could be an IPX name). For interfaces, separate IP and IPX address fields exist.

  9. NNM Continued •  Node selection names are by default the same as the IP Hostname, though users and applications can change the selection name. If the selection names for two objects conflict, a numeric ID string is appended to one of the selection names in order to achieve uniqueness. • For node labels the rules are (applied in order): • 1) If the node has an IP hostname (see 1a and 1b under names above), then the label is the IP hostname truncated to just the basename. •   2) Otherwise, if the node is a NetWare server: •   2a) If the node has a NetWare Server Name, it is used as the label. •   2b) Otherwise, the label is the network number of the internal Server address (i.e. the 000000000001, which is the same for every server, is removed).

  10. NNM Continued •   3) Otherwise, if the node supports SNMP and reports a SNMP sysName value, that value is used as the label. •   4) Otherwise, if the node supports IP, an IP address is used as the label (see 1c in the "names" section). •   5) Otherwise, if the node supports IPX, the host-address portion of the IPX address is used as the label. The address is formatted to translate the vendor of the hardware. (E.g. 100:080009ABCDEF gets a label of "HP-ABCDEF"). •   6) Otherwise, if the node has a LLA/MAC, the physaddr formatting as described in (5) is performed and the result is used as the label.

  11. Proper Multi-Homed Host Naming • A single host name mapped to all IP Addresses • Each interface aliased as a separate hostname if needed. • For instance: • 10.1.1.1 router1 router1.unknowndomain.com e0-router1 • 10.1.2.1 router1 router1.unknowndomain.com e1-router1 • 10.1.3.1 router1 router1.unknowndomain.com s0-router1 • 10.1.4.1 router1 router1.unknowndomain.com s1-router1

  12. A Web Hosting Example • 10.1.1.10 web1 web1.unknowndomain.com nfs-web1 • 10.1.1.11 web1 web1.unknowndomain.comwww.customer1.com • 10.1.1.12 web1 web1.unknowndomain.com www.customer2.com • 10.1.1.13 web1 web1.unknowndomain.com www.customer3.com • 10.1.1.14 web1 web1.unknowndomain.com www.customer4.com • 10.1.1.15 web1 web1.unknowndomain.com www.customer5.com

  13. What Happens When Things Go Wrong • The Labels appear screwed up. • The Events DB takes a long time to load. • Problems with double-clicking on an event to go to a sub-map occur. • Pair-wise Correlation breaks. • Events lookup of a Node don’t show all of the events. • Discovery doesn’t work properly. • Nodes may show up as separate entities although they are part of a single node. • SNMPCollect doesn’t poll correctly. • Tools don’t work that are launchable to a Node. • The events show up slowly in some cases. • Community Strings become a nightmare to maintain. • The Application thrashes performance wise. • It can impair the performance of third party products.

  14. Process “Heavy Hitters” • Xnmevents – All events resolved from an IP Address to a Host Name • Netmon – IP Addresses are resolved to a Host Name for discovery & configuration checks. • SNMPCollect – If host names are used in the configuration, host names resolved back to IP Addresses. • Tools – Dependent upon ARFs definition of fields use. I.e. Telnet $OVSelection1

  15. Common Mistakes • Using illegal characters in a host name. • Treating each IP address / Hostname as an exclusive pair. • Having a forward lookup but not a backward entry. • Not maintaining the DNS Service database.

  16. Recommendations • If you use files, make them DNS or NIS ready. • Larger installations should use DNS locally. • Check your integration with the script checkDNS.ovpl in /opt/OV/support.

  17. Comments? Questions?

More Related