Hi,

Most of the times I get queries about my preparation for Juniper SP track. While the questions are based on two categories, one what study materials have i used, secondly how i practiced. While the first question is something which I will cover in another blog post, this is mainly based on second Query on how did i practice.

I worked for Juniper Networks – So Its sort of Obvious that i had access to devices, mostly the high end ones like T640 and T320 , T320 with XE-interface Loop was my all time favorite though.

Secondly, again my work experience helped with a huge migration from Juniper 120 boxes to Cisco ASR series and had a lot of fun and struggle then.

But for JNCIE exam, all that matters would be how good you are actually at technology. It will really not matter if you are using a VMX or Real device say Mx/Ex/M/T/SRX box, a simple olive can also do, service provider Layer-3 preparation is beautiful 🙂

Coming to the point, I had access to device which has no Mic Cards, No Physical interfaces (literally not coming up) so i cannot use a loop-cable to do what so ever in regular fashion.

It was just lying around there, waiting for its turn to be Turned off. I was to do some internal training’s and saw this guy perfectly suitable for 14 odd routers by using Logical Tunnel interface. Yes, if you have an MX , even if its physically not possible to loop around, you can build your virtual systems and play around using LT.

 

First things first, I will show you the procedure for building Two Logical Routers, but procedure remains same for almost any number of routers


R1(lt-1/0/0.1)(5.5.12.1)------------R2(lt-1/0/0.2)(5.5.12.2)

 

 

This is interface that you should be looking for


show inter terse | match lt
lt-1/0/0 up up


 

 

This is how you build the tunnel interfaces


Test#show interfaces lt-1/0/0
unit 1 {
encapsulation frame-relay;
peer-unit 2; ( logical unit number of the opposite-end connecting interface)
dlci 12;
family inet {
5.5.12.1/24;
}
}
unit 2 {
encapsulation frame-relay;
peer-unit 1;( logical unit number of the opposite-end connecting interface)
dlci 12;
family inet {
5.5.12.2/24;
}
}

 

Finally you integrate them into logical-systems


test#show logical-systems
r1 {
interfaces {
lt-1/0/0 {
unit 1;
}
}
}

r2 {
interfaces {
lt-1/0/0 {
unit 2;
}
}
}

commit
run ping 5.5.12.1 logical-system r2
PING 5.5.12.1 (5.5.12.1): 56 data bytes
64 bytes from 5.5.12.1 icmp_seq=0 ttl=64 time=0/650ms
^C

Regards
Rakesh