isis and ospf is a very similar network protocol (belonging to the dynamic routing protocol), which is used in the huge size of the network, such as operators and banks.
It is also based on the same link-state algorithm, support clnp network, ip network. Ospf different and that it is based on the data link layer packet transmission, and is calculated in ospf ip layer.
It can automatically discover remote network, as long as the network topology changes, the router to exchange routing information with each other, not only can automatically learn the new added network, may also find an alternate path when the current network failure.
Classless Routing Protocol Manager 115 metric from each of the interfaces 10.
2. The overall topology
ISIS routers are classified into three types, i.e., L1 router (Leve-1), L2 router (Leve-2), and L1 / 2 (Leve-1/ 2) router. To support large scale networks, ISIS uses non-backbone areas and backbone regional levels of hierarchy within an autonomous system. Generally, Leve-1 routers deployed in a non-backbone areas, Leve-2 routers, and Level-1/2 backbone routers deployed in the region. Each non-backbone regions are connected by Level-1/2 to the backbone routers. A network running IS-IS protocol, multi-area networks it is very similar to OSPF topology. That L1 to L2 must go through L1 / 2 is connected. (L1 can not learn to L2, L2 but can learn L1, L1 only the default route) as well as the DIS (same priority, MAC is large DIS)
. 3 3.isis different points of the OSPF:
(1) 1s-1s, each router only belong to one area, and in an OSPF router may belong to different interfaces different regions
(2) of the 1S-1S, no concept of a single key area of the non-backbone area. In the OSPF backbone area is defined as Area0
(3) | s-1s in, Leve-1 Leve2 level routing and use the SPF algorithm, to generate the shortest path tree (ShortestPath Tree, spT). In OSPF, only the SPF algorithm is used in the same area, the route between the region needs to be forwarded by the backbone area.
4. The network entity name NET (Network Entity Title) refers to the network layer of the device itself, can be seen as a special kind of NSAP (SEL = 00). NET same length of an NSAP, up to 20 bytes, a minimum of 8 bytes. When configuring IS-IS on the router, you only need to consider the NET, NSAP do not have to be concerned about.
For example there is a NET: ab.cdef.1234.5678.9abc.00, then one Area Address for the ab.cdef, System ID is 1234.5678.9abc, SEL 00.
NET consists of three parts:
the length of the area ID, the area ID may be variable (1 to 13 bytes). And the region address the same area all the nodes must be the same.
System ID, a length of a fixed value of 6 bytes.
The last byte SEL, its value must be 00.
IS-IS and CLNP, ES-IS protocol and IDRP combination, providing complete routing over the entire network) of the OSI seven-layer model of the ISO network layer published:
CLNS: Connectionless Network Service (IS-IS (Routing, IGP ))
CLNP: connectionless network protocol (similar to the IP, IPX), CLNS is CLNP supported service
CONS (connection oriented network service) connection-oriented service
CONP: connection-oriented network protocol (connection-oriented network protocol), such as x .25
ES-IS: end systems and Intermediate System Routing Exchange Protocol (End the System to Intermediate the System the Routing the Exchange Protocol)
IDRP: Inter-Domain Routing Protocol (IInter-the Domain the Routing Protocol)
the IS-the IS: Intermediate System to Intermediate System Protocol (Intermediate System to System Intermediate)
of the OSI network layer defines two services: CONS and CLNS
CLNS-based services supported by the network layer protocol
- CLNP: Connectionless Network Layer Protocol
- ES-IS: Terminal System - Intermediate System Routing Protocol
- IS-IS: Intermediate System - Intermediate System Routing Protocol
isis experimental protocol is as follows:
configure the IP:
Rl-Ll 192.160.1.254 13.1.1.1
R2-Ll 192.160.2.254 23.1.1.2
R3-Ll / 2 13.1.1.3 23.1.1.3 34.1 .1.3
R4-L2 of 192.160.4.254 34.1.1.4
PC1 192.160.1.1
PC2 192.160.2.1
PC4 192.160.4.1
network is not connected.
PT found this emulator does not support isis command, only for GNS3 emulator.
13.1.1.1 Rl (Loopback 1.1.1.1
R2 23.1.1.2 (2.2.2.2 Loopback
R3 13.1.1.3 23.1.1.3 34.1.1.3 (3.3.3.3 Loopback
R4 34.1.1.4 (4.4.4.4 Loopback
the isis protocol: Each interface isis process number needs to be associated.
Rl #
Configure Terminal
CLNS routing service opening CLNS
interface E 0/1
CLNS CLNS Router isis enable routing on the interface isis
isis circuit-typelevel-1 modified link interface type is L1, the default level of L1 / L2 (modified interface type, preferably optimized path table)
router isis ISIS routing protocol is enabled. 1, process number. 1 (1-65535)
is provided. 1-router-type type Level Ll
NO open the shutdown port
router isis isis start protocol
is -type level-1 type disposed router Ll
NET configuration 11.0000.0000.0011.00 NET address; the NET address area by the address (11), the system ID (0000.0000.0011) and NSEL (00) consisting of
exit
following another configuration:
CLNS open CLNS routing service
router isis 1 start isis protocol process 1
is-type level-1 type disposed router Ll
NET NET is configured address 11.0000.0000.0011.00; NET address area by the address (11), the system ID (0000.0000.0011) and NSEL (00) consisting of
interface E 0/1
IP Router ISIS 1 in the interface process related isis
isis circuit-type level-1 interface and the neighbor of the neighbor can only establish the level-1 (modified interface type, preferably optimized path table)
See R1, R2, R3, R4 routing table show ip route
found no routing information R1 R2, R4, and R2, R3, R4 routing information R1.
Because by default, L2 to L1 injection route does not, even by L1 / 2 nor router.
Therefore, L1 is found not ping L2 R1 R2 and R4, R2 and R4 are but can ping R1.
So L1 To access the L2, it needs to be routed leak.
ISIS routing disclosure: is the release of specific routing area L2 to L1 region which go to L1 is possible to select the better route.
List 100 the permit IP-Access 1.1.1.0 Host the any
the redistribute ISIS-IP Level 2 Level-INTO-List 100. 1 the distribute
this L1 region can access the L2 region.