- Link state protocol
- Large ISP used it
- Use Dijkstra's SPF alorithm to calculate OSI route.
- use Partia Route Calculation for IP routes (much effiecient than SPF)
- use "Default metric" (1 ~ 63), VS OSPF use bandwidth
- OSI addressing
- No need backbone area, but use Level
- It was developed by OSI model. and it was design for OSI and well fit to the model
- Integrated ISIS support TCP/IP model(carrying tcp/ip info).. and it was well fit to TCP/IP so.. Very litter modification requires for IPv6.
## OSI address ##
- Hexadecimal
- Reading right to left
- Three parts
- Area ID (Veriable length)
- System ID (6 Bytes), it need to be unique, it can be MAC address.
- NSEL(1Byt)
example
- 49.0003.1111.2222.3333.00
00 = NSEL
1111.2222.3333 = System ID
49.0003 = Area ID
- 49.0141.4176.1AB2.FE00.63c9.00
- 49.0005.1111.1111.1111.00
** 49. is private range
## Routing table
IS-IS Routing maintains two IP routing databases
- Level 1 database : includes Intra-area routes
- Level 2 database : includes Backbone routes
Router can be L1, L2 or L1/L2
## Configuration
1. Enable IS-IS on the router
* automatically create L1 and L2 database, unless create is-type.
** if you are not tagging, default is "0"
Router(config)# router isis
Router(config-router)# net 49.0001.1111.1111.1111.00
2. Configure single OSI address per each router
3. Enable ISIS on per interface basis
** sending both L1/L2 hello packet to interface which is enable ISIS
*** Default metric 10, which is lower than Rip
Router(config)# interface serial1/0
Router(config-if)# ip router isis
4. Summary
summary-address 172.16.0.0 255.255.0.0 level 1 or level 2 or level 1/2 ; have to specify what database will be updated.
5. Redistribute
- To redistrubte ISIS to other protocol, network that is directly connected couldn't be redistrubuted... so use redistrubte connected with route-map to block some of route that doesn't want to redistrubte.
ISIS protocol study summary
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