Adding Seed Routers

You can define Seed Routers for NetMRI to speed up network discovery. The definition of seed routers is highly recommended for IPv4 networks and is required for IPv6 networks. Seed routers are also given priority (like static IP definitions) for determining which devices are counted toward NetMRI's license limits.

For the discovery of any IPv6 network, at least one well-connected IPv6 router (preferably with routes to all other networks to be managed by NetMRI) must be placed in the Seed Router list. In some cases, seed routers may not have the full routing tables or be unable to provide full information for some reason. The general rule of thumb is that more seed routers are better, but the connectivity of the seed router(s) also helps determine how many seed routers you need. Avoid having more seed entries than necessary. Also, note that seed routers are included in the CIDRs count that should not exceed 1000 per the recommendation in the Infoblox Discovery Best Practices Guide.

The Seed Router table lists each defined seed router with its discovery status (as defined on the Network Explorer > Discovery page). By reviewing the discovery status for each seed router, you can determine whether NetMRI should be able to discover the network successfully, or if there are possible configuration errors preventing network discovery without having to wait to see what NetMRI finds.

• For an OC deployment managing a single large network, seed routers can be assigned to each Collector. Choose the network view-collector entry from the Network View list. You will see multiple entries in the pages under the Settings icon > Setup > Discovery Settings for the Network View list. The entire network is assigned to a single network view. However, each network view entry is identified through the association of each Collector. This allows you to edit discovery settings for each Collector in the same network view.
  
  Examples:

Network 1 (NM35) 
Network 1 (NM36) 
Here each Collector, NM35 and NM36, is associated with the same network view.

• For an OC deployment managing multiple networks, you choose the desired Collector from the Filter by Collector list. Then, select the network view under the Network View list. Also bear in mind that any single Collector can have multiple network views.

You can enter IPv6 seed router values in a different fashion from a conventional IPv4 router address because the address value is longer and is formatted differently. You can use the same data entry field for adding a new seed router whether the entry is an IPv4 or IPv6 address.

Seed router values have other considerations when working with IPv6. Collected IPv6 routing information uses link-local unicast (indicated with the FE80: prefix) addresses as the next hops from a current device, but globally advertised routes (or local IPv6 unicast routes that are known throughout the enterprise network) will not automatically be available. Because NetMRI uses routing protocol advertisements and other elements to determine global addresses of next hops for further discovery, the lack of global routing advertisements in IPv6 limits the detection of IPv6 router addresses.

As a result, one or more globally accessible IPv6 router addresses must be added as seed routers (whether local unicast or global unicast is dependent on the network). Ideally, the seed router would have routes to all other locations in the network. Otherwise, you will need more than one seed router value to discover the full network. Do not enter link-local router addresses as seed routers, because link-local addresses have no significance for devices such as NetMRI that are not locally attached to that link.

After NetMRI discovers the routers and collects their routing tables, it uses that information to communicate with and discover adjacent routers, and other devices local to the seed router and otherwise discovered in that part of the topology–including any routers in defined Ranges–to discover the next series of hops in the IPv6 network. The process continues until all IPv6 devices are discovered, including endpoints.

To add new router values into the Seed Routers table, perform the following:

1. Click the Settings icon > Setup > Discovery Settings > Seed Routers, and then click New.
2. Enter the new value into the Seed Router IP Address field.
3. (For Operations Center only) From the Filter by Collector: dropdown menu, choose the Collector from the list.
4. Choose the network view with which the seed router will be associated, by clicking the Network View drop-down menu. This step is required.
   • If this is part of the first discovery of the network, and no other network views are configured, the Network View selector does not appear, and the default Network 1 network view is automatically assigned. Otherwise, choose another network view from the list.
     
     Or
     
     
   • (For Operations Center only) From the Network View drop-down menu, choose the network view to which the seed router for discovery will be assigned. If a network view is divided among two or more Collectors, choose the desired network view based upon the associated Collector name.

5. Once the new value is entered into the Seed Routers table, click Add and Discover to immediately begin the discovery process, or click Add to place the router value into the table for later discovery.