DX NetOps

Hi All,

Can someone please explain to me in detail what is needed for this functionality to work and what the steps are which Spectrum takes in order to consider 2 devices to be connected?

Is there any documentation explaining this?

I assume it would be using arp/cam/cdp/etc to work this out, but I'd like a detailed explanation and if any of the previously mentioned methods have priority over another and what SNMP queries are used in order to get this information.

Thanks in advance!

Regards,

Frank

Hi,

There are several options for "Discover Connections" in CA Spectrum: (from the Modeling and Managing Your IT Infrastructure Administrator Guide page 51/52)

IP Address Tables
When this option is disabled, Discovery disables Layer 3 mapping and maps only the Layer 2 connections. In addition, when this option is disabled, Discovery automatically disables the IP Route Tables Protocol option, the Create Wide Area Link Model option, the Create LANs (IPSubnets) option, and the Remove Empty LANs options.

IP Route Tables
Specifies whether CA Spectrum will use the IP Address Table to map routers. This option is set to No by default because these tables can be very large and very time-consuming for CA Spectrum to read. When this option is enabled, CA Spectrum will not be able to map unnumbered IP interfaces (0.0.0.0).

Source Address Tables
When enabled, Discovery uses the device Source Address table to map layer 2 connectivity.

Discovery Protocol Tables
When this option is enabled, Discovery uses the Discovery Protocol tables to map device connectivity. Currently this option supports Cisco, Nortel, Cabletron Switch, Extreme, Alcatel, Foundry, and Link Layer discovery protocols.

ARP Tables for Pingables
When enabled, Discovery uses the ARP table to determine pingable MAC addresses for the connectivity mapping.

Spanning Tree
When enabled, Discovery uses the device Spanning Tree Address table (SAT) when mapping layer 2 connectivity information about the device.

Traffic Resolution
When enabled, Discovery uses network traffic data to determine connections between interfaces. In many cases, having Discovery use the traffic data eliminates the need to model Fanout segments.

ATM Protocols
Disabled by default. When enabled, the ATM Discovery runs against all ATM switches in the SpectroSERVER database. See the ATM Circuit Manager User Guide for more information.


If you have a network with nearly the same vendor devices (like Cisco), the "Discovery Protocol Tables" are very helpful for the discovery of the connections between these network devices. For the end-point discovery (e.g. server) the "ARP Tables for Pingables" is mostly used. Spectrum will search the MAC address of the end-point device in the forwarding tables of the Access switches. The "Traffic Resolution" is the "last Hope", but I never get good results with the technique.

Regards,
Christoph

Hi Frank,

The following KB article should help.

https://comm.support.ca.com/?legacyid=TEC583592

Regards,
Widjaja

Thanks for the responses. I'll have a look at these. From my understanding these were to do with Autodiscovery. I thought these settings had to do with when you want Spectrum to go out and find devices (which is not what I want to do!).

I have a script which models devices and what I am doing then is getting Spectrum to initiate a 'discover connections' to create the connections. After it does this I enable live links and set some attributes.

I want to know exactly what is needed in order for Spectrum to create an association 'Links_with' with another port/interface. I can see both have arp/mac/ip tables and believe Spectrum should have enough information to link 2 devices together but it's not connecting them!

Thanks again!

Frank