IS-IS (Intermediate System to Intermediate System) — the dynamic routing internal protocol.

The configuring process of IS-IS protocol consists of several steps. After IS-IS network design is selected the basic configuring is to enable IS-IS protocol on a routers, configuring a unique NET-address and enabling a protocol on interfaces.

Configuration steps:

Step 1.

Enter the protocol configuration mode using the router isis <process name> command, where process name can be set of letters and numbers or be omitted.

Step 2.

Configure router's NET-address using the net <address> command, where address length should be from 8 to 20 byte. The last byte is a n-selector (SEL) and must be set to 0. The 6th byte before the n-selector is a system identifyer (System-ID), the bytes 1th-13th are area idenrifyer (area ID). By default a router can have 3 NET-addresses in a different areas, but system identifyer must be the same. Use the max-area-address <value> command to increase a number of NET-addresses.

Step 3.

To specify the level which the router would work on in the IS-IS protocol configuration mode use the is-type <level-1/level-1-2/level-2-only> command, by default it's L1/L2. One can specify connection type on interface using the isis circuit-type <level-1/level-1-2/level-2-only> command, by default it's L1/L2.

Step 4.

To specify the network type in the interface configuration mode use the isis network command. The possible network type is broadcast or point-to-point.

Step 5.

To specify timers' values in the interface configuration mode use the isis hello-interval command or change the multiplier hold-timer by using the isis hello-multiplier <value> command.

Step 6.

Configure manually interfaces' costs for best route choice affecting. To do this in interface configuration mode use the isis metric <value> command.

Step 7.

IS-IS protocol authentification. The EcoRouterOS supports clear-text and md5 authentification via key chains.

Configure an authentification on each one interface separately. For clear-text authentification configuringe in the configuration interface mode use the isis password <string> [level-1/level-2] command, where string's maximum length is 254 symbols. To configure md5 authentificzation use the isis authentication mode md5 and the isis authentication key-chain <key chain's name> [level-1/level-2] commands. To specify the key chain's name in the key chain configuration mode use the key chain <key chain's name> command, one can specify several passwords and key chain names.

Configuration example

Step 1. Specifying device name.

ecorouter(config)#hostname ECO-1

Step 2. Ports, interfaces and service instanse configuring.

ecorouter(config)#interface e2

ecorouter(config-if)#ip address 10.12.0.1/16

ecorouter(config)#interface e3

ecorouter(config-if)#ip address 10.13.0.1/16

ecorouter(config)#port ge2

ecorouter(config-port)#service-instance ge2/e2

ecorouter(config-service-instance)#encapsulation untagged

ecorouter(config-service-instance)#connect ip interface e2

ecorouter(config)#port ge2

ecorouter(config-port)#service-instance ge2/e2

ecorouter(config-service-instance)#encapsulation untagged

ecorouter(config-service-instance)#connect ip interface e2

Step 3. Routing enabling.

ecorouter(config)#router isis 

ecorouter(config-router)#net 49.0001.0000.0000.0001.00 

ecorouter(config-router)#exit 

ecorouter(config)#interface e2

ecorouter(config-int)#ip router isis

ecorouter(config-int)#interface e3

ecorouter(config-int)#ip router isis

ecorouter(config-int)#exit

Step 4. Authentification between neighbors enabling.

ecorouter(config)#key chain test

ecorouter(config-keychain)#key 1

ecorouter(config-keychain-key)#key-string ecorouter

ecorouter(config-keychain-key)#exit 
ecorouter(config-keychain)#exit 
ecorouter(config)#interface e2
ecorouter(config-if)#isis authentication mode md5 
ecorouter(config-if)#isis authentication key-chain test 
ecorouter(config)#interface e3
ecorouter(config-if)#isis authentication mode md5 
ecorouter(config-if)#isis authentication key-chain test

The other routers should be configured in the same way.

hostname ECO-2

key chain test2

key 2

key-string 0x8de456332b943f870ef377482f699e4c

interface e1

ip address 10.12.0.2/16

ip router isis

interface e3

ip address 10.23.0.2/16

ip router isis

port ge1

service-instance ge1/e1

encapsulation untagged

connect ip interface e1

port ge2

service-instance ge2/e2

encapsulation untagged

connect ip interface e2

router isis

net 49.0001.0000.0000.0002.00

hostname ECO-3

key chain test3

key 3

key-string 0x8de456332b943f870ef377482f699e4c

interface e1

ip address 10.13.0.3/16

ip router isis

interface e2

ip address 10.23.0.3/16

ip router isis

port ge1

service-instance ge1/e1

encapsulation untagged

connect ip interface e1

port ge2

service-instance ge2/e2

encapsulation untagged

connect ip interface e2

router isis

net 49.0001.0000.0000.0003.00

Redistribution, filtering and route summarizing

One can permit or deny subnet routing information transmition when redistributing routes are from different IS-IS levels. One can configure policy-filter-list, route-map with the permit или deny rules and apply them to the distribute-list (to read more about lists and route maps see the relevant sections). The configuration command is redistribute isis <level-1/level-2 > into <level-2/level-1> distribute-list <name>.

Only route-maps to manage route information transfer from another routing protocol can be used. The configuration command is redistribute <connected/static/rip/ospf/bgp> [metric <0-63>] [metric- type <internal/external>] [level-1/level-2/level-1-2] [route-map <name>].

Use the summary-address <address/mask> [level-1/level-2/level-1-2] [metric <0-63>] command for routes summarising.

Use the metric <значение > [ systemID <policy-filter-list ID>] command to specify the administrative distance value for IS-IS routes, where systemID is system neighbor identifyer (this neighbor advertises subnets).

Default routes and mesh-groups

To reduce IS-IS routing table size EcoRouterOS allows to configure advertising default routes to the neighbors. When connecting L1/L2 router to different areas in route advertising the default route will be sent to L1-neighbor. The L1/L2 router's address will be sent as a next-hop address. To send the default route to neighbor use the default-information originate [always] [route-map] command, where the always parameter doesn't take into account if the default route is in its own routing table, the route-map parameter allows to select a particular subnet.

To control LSP flooding in NBMA links EcoRouterOS allows to add interfaces into different mesh-groups which sets some specific rules on subnet information packets handling.

In the interface configuration mode the command is isis mesh-group <value/blocked>. If LSP is recieved onto interface which is not in the mesh-group, the LSP transmits further usually. If LSP is recieved onto interface which is in the mesh-group, the LSP transmits further to all interfaces excluding which are in the same group or marked as blocked.

Additional configuration commands

See additional IS-IS protocol configuration commands in the table below. 

Viewing commands

See protocol infromation related commands in the table below. Just like the other show commands they support modificators using.