ISIS Configuration on Juniper

Juniper-ISIS-configuration-example

ISIS Configuration on Juniper

ISIS Protocol is a very good Routing Protocol. But it is rarely used nowadays. Instead ISIS Protocol, OSPF is generally used Routing Protocol. By the way, there are still some common Service Providers are using ISIS. So, it is a very good talent to know ISIS Protocol.

In th lesson, we will see how to configure basic ISIS network with Juniper routers.

We will use the below topology.

Juniper-ISIS-confiAguration-example

Let’s see the ISIS Configuration steps one by one.

Step 1 – Enabling ISIS on the Router

Firstly, we will enable ISIS on all routers.

Juniper-RouterA@Kosem> configure

[edit]
Juniper-RouterA@Kosem# security forwarding-options family iso

[edit security forwarding-options family iso]
Juniper-RouterA@Kosem# set mode packet-based

Step 2 – IP Address Configuration

We will use the below IP subnets for our Juniper ISIS Confgiguration example.

Segment IP Subnet

RouterA-RouterB 10.10.10.0/24
RouterA-RouterC 10.10.20.0/24
RouterB-RouterC 10.10.30.0/24
RouterC-RouterD 10.10.40.0/24

Juniper-RouterA@Kosem# set interfaces ge-2/1/1 unit 0 family inet address 10.10.10.2/24
Juniper-RouterA@Kosem# set interfaces ge-2/1/2 unit 0 family inet address 10.10.20.1/24

Juniper-RouterB@Kosem# set interfaces ge-2/1/1 unit 0 family inet address 10.10.30.2/24
Juniper-RouterB@Kosem# set interfaces ge-2/1/2 unit 0 family inet address 10.10.10.2/24

Juniper-RouterC@Kosem# set interfaces ge-2/1/1 unit 0 family inet address 10.10.20.1/24
Juniper-RouterC@Kosem# set interfaces ge-2/1/2 unit 0 family inet address 10.10.30.1/24
Juniper-RouterC@Kosem# set interfaces ge-2/1/3 unit 0 family inet address 10.10.40.1/24

Juniper-RouterD@Kosem# set interfaces ge-2/1/1 unit 0 family inet address 10.10.40.2/24

Step 3 – Enabling ISIS on the Router

By default Juniper routers accept IP packets but not other packets. To enable to get ISIS packets, we need to enable the interfaces.

Juniper-RouterA@Kosem# set interfaces ge-2/1/1 unit 0 family iso
Juniper-RouterA@Kosem# set interfaces ge-2/1/2 unit 0 family iso

Juniper-RouterB@Kosem# set interfaces ge-2/1/1 unit 0 family iso
Juniper-RouterB@Kosem# set interfaces ge-2/1/2 unit 0 family iso

Juniper-RouterC@Kosem# set interfaces ge-2/1/1 unit 0 family iso
Juniper-RouterC@Kosem# set interfaces ge-2/1/2 unit 0 family iso
Juniper-RouterC@Kosem# set interfaces ge-2/1/3 unit 0 family iso

Juniper-RouterD@Kosem# set interfaces ge-2/1/1 unit 0 family iso

Step 4 – Creating Loopback IPs and ISIS NET addresses

We will use the below IP and NET addresses for Loopbacks.

Router Lo0 IP Area ID Lo0 NET
Router A 1.1.1.1 49.0001 49.0001.1111.1111.1111.00
Router B 2.2.2.2 49.0002 49.0002.2222.2222.2222.00
Router C 3.3.3.3 49.0003 49.0003.3333.3333.3333.00
Router D 4.4.4.4 49.0003 49.0003.3030.3030.3030.00

As we diccussed in ISIS lessons, ISIS needs one NET address per router. We will give this address to the Loopback Interface.

This NET address consist of some parts. These parts and the corresponding areas are given below :

• AFI (Area Family ID) 49
• Area ID 0001
• System ID 1111.1111.1111
• NSEL (NET Selector) 00

Now, let’s configure these addresses for Loopback 0 on each router.

Juniper-RouterA@Kosem# set interfaces lo0 unit 0 family inet address 1.1.1.1/32
Juniper-RouterA@Kosem# set interfaces lo0 unit 0 family iso address 49.0001.1111.1111.1111.00

Juniper-RouterB@Kosem# set interfaces lo0 unit 0 family inet address 2.2.2.2/32
Juniper-RouterB@Kosem# set interfaces lo0 unit 0 family iso address 49.0002.2222.2222.2222.00

Juniper-RouterC@Kosem# set interfaces lo0 unit 0 family inet address 3.3.3.3/32
Juniper-RouterC@Kosem# set interfaces lo0 unit 0 family iso address 49.0003.3333.3333.3333.00

Juniper-RouterD@Kosem# set interfaces lo0 unit 0 family inet address 4.4.4.4/32
Juniper-RouterD@Kosem# set interfaces lo0 unit 0 family iso address 49.0003.3030.3030.3030.00

Step 5 – Router Roles

There are three roles of ISIS Router. These are :

• L1 Router
• L2 Router
• L1/L2 Router

Here, we will give the roles of each ISIS Router.

By default all the routers are L1/L2 Router. If we would like to give an Interface only one Role (For example Layer 1 Router), we will disable the other role (Level 2 Router) on the interface.

Juniper-RouterA@Kosem# set protocols isisi interfaces ge-2/1/1 level 1 disable
Juniper-RouterA@Kosem# set protocols isisi interfaces ge-2/1/2 level 1 disable

Juniper-RouterB@Kosem# set protocols isisi interfaces ge-2/1/1 level 1 disable
Juniper-RouterB@Kosem# set protocols isisi interfaces ge-2/1/2 level 1 disable

Juniper-RouterC@Kosem# set protocols isisi interfaces ge-2/1/1 level 1 disable
Juniper-RouterC@Kosem# set protocols isisi interfaces ge-2/1/2 level 1 disable
Juniper-RouterC@Kosem# set protocols isisi interfaces ge-2/1/3 level 2 disable

Juniper-RouterD@Kosem# set protocols isisi interfaces ge-2/1/1 level 2 disable

By doing this, we provide the Layer 2 ISIS connection betweeen Router A, RouterB and Router C. Beside, the connection between RouterC and RouterD is Level 1.

Step 6 – Assigning Interfaces under ISIS

This is the step that we add the interfaces under ISIS protocol in each router.

Juniper-RouterA@Kosem# set protocols isisi interfaces ge-2/1/1
Juniper-RouterA@Kosem# set protocols isisi interfaces ge-2/1/2
Juniper-RouterA@Kosem# set protocols isisi interfaces lo0

Juniper-RouterB@Kosem# set protocols isisi interfaces ge-2/1/1
Juniper-RouterB@Kosem# set protocols isisi interfaces ge-2/1/2
Juniper-RouterB@Kosem# set protocols isisi interfaces lo0

Juniper-RouterC@Kosem# set protocols isisi interfaces ge-2/1/1
Juniper-RouterC@Kosem# set protocols isisi interfaces ge-2/1/2
Juniper-RouterC@Kosem# set protocols isisi interfaces ge-2/1/3
Juniper-RouterC@Kosem# set protocols isisi interfaces lo0

Juniper-RouterD@Kosem# set protocols isisi interfaces ge-2/1/1

Step 7 – Verifying ISIS on the Juniper Routers

To verify the ISIS connection, we can use the below show commands in Juniper routers.

• show isis adjacency
• show isis interface
• show isis route
• show route protocol isis

Juniper-RouterA@Kosem> show isis adjacency
Interface System L State Hold (secs) SNPA
ge-2/1/1.0 RouterB 2 Up 17
ge-2/1/2.0 RouterC 2 Up 18

Juniper-RouterA@Kosem> show isis interface
IS-IS interface database:
Interface L CirID Level 1 DR Level 2 DR L1/L2 Metric
lo0.0 0 0x1 Passive Passive 0/0
ge-2/1/1.0 2 0x1 Disabled Point to Point 10/10
ge-2/1/2.0 2 0x1 Disabled Point to Point 10/10

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