Differences between version 6 and previous revision of ISIS.
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| Newer page: | version 6 | Last edited on Monday, August 16, 2004 2:58:13 pm | by LindsayDruett | Revert |
| Older page: | version 5 | Last edited on Monday, August 16, 2004 1:57:26 pm | by LindsayDruett | Revert |
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|Host Address|This is the subset of the NET address, which includes both the domain, area, and system ID.
|Integrated IS-IS|Another term for Dual IS-IS. Indicates IS-IS can be used to support routing for two Layer 3 protocols (IP and CLNP) in the same network simultaneously.
|Intermediate system (IS)|A router. The IS is a device capable of directing traffic to remote destinations.
|Intermediate System-to-Intermediate System (IS-IS)|The OSI routing protocol that learns the location of the network within the autonomous system so that data can be forwarded to the remote hosts.
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+|IS-IS domain|A group of routers running the IS-IS protocols for exchanging routing information.
+|Level 1 (L1)|These routers are internal to the area, which means that they receive routing information for their area only and have no knowlege of the other area's networks. The reach other areas, Level 1 routers maintain a default route to the nearest Level 2 router.
+|Level 1-2 (L1-2)|A router that connects areas. This router connects a Level 1 area to the Level 2 backbone. It will have a Level 1 routing table to route to ES and IS in its own area by system ID. It will maintain a Level 2 prefix table to route to other areas.
+|Level 2 (L2)|These router are connected only to the backbone and provide transit traffic between areas.
+|Link|A physical connection to a neighbor. This link is then transmitted to all the other routers in the area via the LSP.
+|Link-state packet (LSP)|A Packet that describes a router's links. these are separate LSPs for Level 1 and Level 2 updates.
+|Neighbor|A router on the same link with which an adjacency is formed and routing information is then exchanged.
+|Network entity title (NET)|Part of an OSI address. The NET describes both the area and system ID of a system in the IS-IS network but excludes the NSEL, which defines the NSAP address of the system.
+|Network protocol data unit (NPDU)|See protocol data unit (PDU).
+|Network Selector (NSEL)|Sometimes referred to as the SEL field. This field describes the service at the network layer by which the packet is to be sent. NSEL is similar to the Protocol filed in IP.
+|Network service access point (NSAP)|Describes a service at the network layer to which the packet is to be directed. The NSAP is the NET address with the SEL field set to a value other than 0x00.
+|Overload (OL) bit|The OL is set on an LSP if the router cannot store the entire link-state database. When other routers receive LSPs with this bit set, they will not send the router any transmit traffic for fear that its routing table is incomplete. If the router is making decisions using incomplete data, its decisions may result in suboptimal paths or even routing loops. Traffic destined for the router can still be sent to the directly connected interfaces of a router transmitting the OL bit in its LSPs.
+|Partial sequence number packet (PSNP)|PSNPs are sent on point-to-point links to acknowlege explicitly each LSP the router recieves. A router on a broadcast subnetwork sends a PSNP requesting the LSPs it needs to synchronize its link-state database.
+|Protocol data unit (PDU)|A unit of data passed from one layer of the OSI model to the same level of the OSI model on another node. Each layer prefixes the PDU to indicate the sending OSI layer so that the network layer sends NPDUs and the data-link layer sends DLPDUs.
+|Pseudonode|The LAN identifier for a broadcast subnetwork. The pseudonode makes the broadcast medium appear as a virtual router and the routers appear as connected interfaces. the routers maintain adjacencies to the pseudonode, which are managed by the DIS, instead of to all other routers on the medium (thus reducing memory, CPU, and bandwitch resources).
+|Routeing Domain|Routeing Domain is the same as the Administrative Domain. It defines the bondaries of a network of interconnected routers operated and managed by the same administrative group.%%%The spelling of Routeing Domain is not a typographic error but the British spelling adopted by the ISO committee.
+|Sequence number PDU (SNP)|SNPs are used to acknowledge the receipt of LSPs and to synchronize link-state databases.
+|Subnetwork|The data-link layer.
+|Subnetwork dependent layer|Interfaces with the data-link layer and hides the different kinds of data-link layers from the network layer. This sublayer transmits and receives PDUs from the subnetwork, translates DLPDUs into NPDUs, and hands them to the appropriate OSI process. The subnetwork dependent layer is also responsible for creating and maintaining adjacencies through the exchange of IS-IS Hello PDUs.
+|Subnetwork independent layer|
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[OSPFvsISIS]
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CategoryNetworking
