IS-IS Discovery
IS-IS links are found in the isisISAdjTable
(defined in the ISIS-MIB module).
This table has the information needed to find the Adjacency Intermediate System.
Each entry in this SNMP MIB table represents a unidirectional link from the Intermediate-System
that is queried to the Adjacent Intermediate Systems running IS-IS and "peering" with the source router.
The information about IS-IS is stored in two tables: isisElement
and isisLink
.
isisElement
contains the ISISSysID
, a unique identifier of the Intermediate-System
(the router’s name in ISO protocols).
If two routers—IS-A and IS-B—support ISIS-MIB, enlinkd creates two link entries in Meridian: one from IS-A to IS-B (from IS-A’s adjTable
), and the complementary link from IS-B to IS-A (from IS-B’s adjTable
).
You can find generic information about the IS-IS link discovery process in the IS-IS Information box on any device’s Node Detail page.
IS-IS Topology Updater
The IS-IS Topology Updater consolidates IS-IS data and provides the IS-IS OnmsTopology. Only full bidirectional connections between two IS-IS-supported devices become edges in the topology. For example, Node A and Node B are connected by an edge if, and only if, there is an IS-IS link in Node A to Node B, and vice versa.
IS-IS links are represented in the ISIS-MIB as in the table of supported OIDs.
Information gathered from supported OIDs is stored in the following database tables:
Supported OIDs
The following OIDs are supported for the discovery and construction of the IS-IS network topology. The IS-IS Discovery Collector collects them:
Name | Description | OID |
---|---|---|
isisSysID |
ID for this |
.1.3.6.1.2.1.138.1.1.1.3.0 |
isisSysAdminState |
Administrative state of this |
.1.3.6.1.2.1.138.1.1.1.8.0 |
isisSysObject |
isisSysObject |
.1.3.6.1.2.1.138.1.1.1 |
isisCircIfIndex |
Value of |
.1.3.6.1.2.1.138.1.3.2.1.2 |
isisCircAdminState |
Administrative state of the circuit. |
.1.3.6.1.2.1.138.1.3.2.1.3 |
isisISAdjState |
State of the adjacency. |
.1.3.6.1.2.1.138.1.6.1.1.2 |
isisISAdjNeighSNPAAddress |
SNPA address of the neighboring system. |
.1.3.6.1.2.1.138.1.6.1.1.4 |
isisISAdjNeighSysType |
Type of the neighboring system. |
.1.3.6.1.2.1.138.1.6.1.1.5 |
isisISAdjNeighSysID |
System ID of the neighboring |
.1.3.6.1.2.1.138.1.6.1.1.6 |
isisISAdjNbrExtendedCircID |
4-byte extended circuit ID learned from the neighbor during three-way handshake, or |
.1.3.6.1.2.1.138.1.6.1.1.7 |