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75 lines
2.4 KiB
ReStructuredText
75 lines
2.4 KiB
ReStructuredText
.. include:: /_include/need_improvement.txt
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.. _isis:
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#####
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IS-IS
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#####
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:abbr:`IS-IS (Intermediate System to Intermediate System)` is a link-state interior gateway routing protocol.
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Like OSPF, IS-IS runs the Dijkstra shortest-path first (SPF) algorithm to create a database of the network’s
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topology and, from that database, to determine the best (that is, shortest) path to a destination.
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The routers exchange topology information with their nearest neighbors.
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IS-IS runs directly on the data link layer (Layer 2).
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IS-IS addresses are called :abbr:`NETs (Network Entity Titles)` and can be 8 to 20 bytes long, but are generally 10 bytes long.
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For example :abbr:`NET (Network Entity Title)`
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.. code-block:: none
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49.0001.1921.6800.1002.00
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The IS-IS address consists of three parts:
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:abbr:`AFI (Address family authority identifier)`
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``49`` The AFI value 49 is what IS-IS uses for private addressing.
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Area identifier:
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``0001`` IS-IS area number (Area1)
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System identifier:
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``1921.6800.1002`` For system idetifier we recommend to use IP address or MAC address of the router.
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NET selector:
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``00`` Must always be 00, to indicate "this system".
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Simple IS-IS configuration using 2 nodes and redistributing connected interfaces.
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**Node 1:**
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.. code-block:: none
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set interfaces dummy dum0 address '203.0.113.1/24'
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set interfaces ethernet eth1 address '192.0.2.1/24'
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set policy prefix-list EXPORT-ISIS rule 10 action 'permit'
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set policy prefix-list EXPORT-ISIS rule 10 prefix '203.0.113.0/24'
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set policy route-map EXPORT-ISIS rule 10 action 'permit'
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set policy route-map EXPORT-ISIS rule 10 match ip address prefix-list 'EXPORT-ISIS'
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set protocols isis FOO interface eth1
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set protocols isis FOO net '49.0001.1921.6800.1002.00'
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set protocols isis FOO redistribute ipv4 connected level-2 route-map 'EXPORT-ISIS'
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**Node 2:**
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.. code-block:: none
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set interfaces ethernet eth1 address '192.0.2.2/24'
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set protocols isis FOO interface eth1
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set protocols isis FOO net '49.0001.1921.6800.2002.00'
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Show ip routes on Node2:
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.. code-block:: none
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vyos@r2:~$ show ip route isis
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Codes: K - kernel route, C - connected, S - static, R - RIP,
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O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
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T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
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F - PBR, f - OpenFabric,
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> - selected route, * - FIB route, q - queued route, r - rejected route
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I 203.0.113.0/24 [115/10] via 192.0.2.1, eth1, 00:03:42
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