Home Routing ISIS ISIS protocol study summary

- 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)

    - 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 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.


Smart Link
Content View Hits : 2287890
Highly recommended firewall vendor?
Google Translation
English Arabic Chinese (Simplified) Czech Dutch French German Italian Korean Portuguese Russian Spanish Filipino Vietnamese Thai Turkish
BGP routing issue?
World Route Servers
Who's Online
We have 27 guests online