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tjloran
Posts: 2
Registered: ‎02-11-2009
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Junos OSPF and Frame-Relay

Hello everyone,

 

I am coming from a strong Cisco background and have some fundamental questions on how Junos does frame-relay and OSPF.

 

I have done the fast-track training, taken JUNOS as a second language, read the jseries configuration guides, and tried the IOS to JUNOS translator but I guess I am too indoctrinated with IOS to understand how JUNOS does certain things (I am trying to fix that):

 

1)  Does JUNOS use anything like the  frame-relay interface-dlci  xxx command?  I assume it is not needed because every time I configure a frame-relay logical unit, I give it a DLCI number.  Am I correct?

 

2)  How does JUNOS do inet and inet6 mapping to frame-relay DLCI on point to multipoint interfaces?  I read the OSPF config guide and understand that JUNOS must have a neighbor statement, but how does that neighbor statement get mapped to a  far end DLCI?  

 

3)  Does / how does JUNOS allow dynamic routing protocols on the NBMA  FR networks? In IOS you have to use the broadcast keyword in you frame-relay map statement otherwise you won't allow multicast over the NBMA interface and OSPF won't form adjacencies?

 

 

Thanks for your consideration,  I am working on   small rack in preperation for my JNCIE-ER exam but don't yet have serieal interfaces to test frame-relay

 

 

 

Super Contributor
masoodnt10
Posts: 80
Registered: ‎06-20-2008
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Re: Junos OSPF and Frame-Relay


tjloran wrote:

Hello everyone,

 

I am coming from a strong Cisco background and have some fundamental questions on how Junos does frame-relay and OSPF.

 

I have done the fast-track training, taken JUNOS as a second language, read the jseries configuration guides, and tried the IOS to JUNOS translator but I guess I am too indoctrinated with IOS to understand how JUNOS does certain things (I am trying to fix that):

 

1)  Does JUNOS use anything like the  frame-relay interface-dlci  xxx command?  I assume it is not needed because every time I configure a frame-relay logical unit, I give it a DLCI number.  Am I correct?

 

Yea correct, frame-relay interface-dlci - You know assigns a DLCI to a specified FR subinterface.
jahil@R1#top set interfaces se-4/2/1 encapsulation frame-relay unit 101 dlci 101 - assigns a DLCI to a specified FR subinterface.
 

 

2)  How does JUNOS do inet and inet6 mapping to frame-relay DLCI on point to multipoint interfaces? 

 

In IPv4 for each destination, you have to configure multipoint-destination statement. For family inet6 I could not find the same stuff.
jahil@R1#top set interfaces se-4/2/1 unit 102 family inet address 1.1.1.1/30 multipoint-destination 1.1.1.2 dlci 201 

 

I read the OSPF config guide and understand that JUNOS must have a neighbor statement, but how does that neighbor statement get mapped to a  far end DLCI?  

 

 

When you configure OSPF on a nonbroadcast, multiaccess nbma network, such as a multipoint FR logical interface, OSPF operates by default in point-to-multipoint mode. In this mode, OSPF treats the network as a set of point-to-point links. Because there is no autodiscovery mechanism, each neighbor must be configured.

 [edit protocols ospf area 0]
 interface interface-name {
   neighbor address ; (To configure multiple neighbors, include a neighbor statement for each neighbor)
   poll-interval seconds; (poll-interval is your friend to controle the periodic hello packets going out, by default 120Sec)
 } 

 

3)  Does / how does JUNOS allow dynamic routing protocols on the NBMA  FR networks? In IOS you have to use the broadcast keyword in you frame-relay map statement otherwise you won't allow multicast over the NBMA interface and OSPF won't form adjacencies?

 

 

To configure nbma mode, include the following statements at the [edit protocols ospf area 0] hierarchy level:

 [edit protocols ospf area 0]
 interface interface-name {
   interface-type nbma; (interface type nbma is the way to go)
   neighbor address <eligible>; (To configure multiple neighbors, include a neighbor statement for each neighbor, If the neighbor is allowed to become the designated router, include the eligible keyword.)
 }
 

OSPF routers normally discover their neighbors dynamically by listening to the broadcast or multicast hello packets on the network. Because an NBMA network does not support broadcast or multicast, the router cannot discover its neighbors dynamically, so you must configure all the neighbors statically. Do this by including the neighbor statement and specifying the IP address of each neighboring router in the address option. To configure multiple neighbors, include multiple neighbor statements Ref: JUNOS OSPF DOCS.

 

 

 

Thanks for your consideration,  I am working on   small rack in preperation for my JNCIE-ER exam but don't yet have serieal interfaces to test frame-relay

 

 

 


 

Regards,
Masood
BLOG: http://weblogs.com.pk/jahil/
Visitor
tjloran
Posts: 2
Registered: ‎02-11-2009
0

Re: Junos OSPF and Frame-Relay

Bingo  that was exactly what I was looking for.  Thanks
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