disable frame inverse arp in INE workbook volume 1

hi all, sorry for this silly post but i am getting bit confused with frame-relay inverse arp feature:-

as i know, The Frame Relay router sends out frame-relay Inverse ARP requests on its Frame Relay PVC to discover the protocol address of the remote device connected to the Frame Relay network. 

but when i go through with INE workbook vol 1 section 2.9 in frame-relay:- Disabling inverse-arp

R5 have two subinterfaces as s1/0.100 multipoint and s1/0.200 multipoint---------

R5's1/0.100multipoint is connected with R1 and R2 in same subnet as 155.1.100.0/24 and R5's1/0.200multipoint is connected with R3's1/0.999 and R4s1/0.999 in another same subnet as 155.1.200.0/24:-

as question is mentioned in workbook:-

1. use multipoint subinterface s1/0.100 on R5 with 501 and 502 DLCIs and as well another multipoint subinterface s1/0.200 is using 503 and 504 DLCIs.

2. configure R1 and R2 so that they will not send inverse-arp request for IP out any DLCI learn from frame-relay cloud other than those in diagram.

3. configure R3 and R4 to disable inverse-arp on DLCI learned from frame-relay cloud that are not listed in the diagram by asgining them to subinterface 999.

4. ensure that R5 can get ping with R1, R2, R3 and R4 as unicast, broadcast and multicast massages but all other R1, R2, R3 and R4 can not get ping with each other.

solution is done by me:-

R5#sh run int s1/0.100


interface Serial1/0.100 multipoint

 ip address 155.1.100.5 255.255.255.0

 frame-relay interface-dlci 501

 frame-relay interface-dlci 502


R5#sh run int s1/0.200

interface Serial1/0.200 multipoint

 ip address 155.1.200.5 255.255.255.0

 frame-relay interface-dlci 503

 frame-relay interface-dlci 504


Rack1R5#sh frame map

Serial1/0.100 (up): ip 155.1.100.1 dlci 501(0x1F5,0x7C50), dynamic,

              broadcast,, status defined, active

Serial1/0.100 (up): ip 155.1.100.2 dlci 502(0x1F6,0x7C60), dynamic,

              broadcast,, status defined, active

Serial1/0.200 (up): ip 155.1.200.3 dlci 503(0x1F7,0x7C70), dynamic,

              broadcast,, status defined, active

Serial1/0.200 (up): ip 155.1.200.4 dlci 504(0x1F8,0x7C80), dynamic,

              broadcast,, status defined, active

reson being R5 is using only DLCIs to map with R1 and R2, not mentioned about any static mapping with R1 and R2 as i understood from these question

so solution on R1-------

R1#sh run int s1/0


interface Serial1/0

 ip address 155.1.100.1 255.255.255.0

 encapsulation frame-relay

 serial restart-delay 0

 no frame-relay inverse-arp IP 102

 no frame-relay inverse-arp IP 103

 no frame-relay inverse-arp IP 104

end

R2#sh run int s1/0


interface Serial1/0

 ip address 155.1.100.2 255.255.255.0

 encapsulation frame-relay

 serial restart-delay 0

 no frame-relay inverse-arp IP 201

 no frame-relay inverse-arp IP 203

 no frame-relay inverse-arp IP 204

end



reason being R1 and R2 can not send inverse-arp to ip learned via LMI


but on R3 and R4 not mentioning which subinterface should i use so firstly i use point-2-point then


R3# sh run int s1/0.999 point-2-point


interface Serial1/0.999 point-to-point

 ip address 155.1.200.3 255.255.255.0

 frame-relay interface-dlci 305

end



R4#sh run int s1/0.999 p


interface Serial1/0.999 point-to-point

 ip address 155.1.200.4 255.255.255.0

 frame-relay interface-dlci 405

end



reason being need to disable inverse-arp on DLCIs learned from frame-relay clound but when i check that R5 is having right mapping with R1, R2, R3 and R4 and R1, R2, R3, R4 is also having right mapping with R5 as well as R1, R2, R3 and R4 is not having mapping each other such that:-

R1# sh frame map

Serial1/0 (up): ip 155.1.100.5 dlci 105(0x69,0x1890), dynamic,

              broadcast,

              CISCO, status defined, active

R2#sh frame map

Serial1/0 (up): ip 155.1.100.5 dlci 205(0xCD,0x30D0), dynamic,

              broadcast,, status defined, active

R3#sh frame map

Serial1/0.999 (up): point-to-point dlci, dlci 305(0x131,0x4C10), broadcast

          status defined, active

R4#sh frame map


Serial1/0.999 (up): point-to-point dlci, dlci 405(0x195,0x6450), broadcast

          status defined, active



i also know according this question R3 and R4 can not be configured with no frame-realy inverse-arp ip 301, 302 and 401, 402. so the only configuration can be possible here is done here with pont-2-point interface on R3 and R4 so would this be right for this task?


if any other solution can be possible here then please confirm me with point-2-point!!


now other way :- on R3 and R4 is having multipoint subinterfaces such as s1/0.888 multipoint

we can configure static mapping on R3 and R4 with R5 so that it will automatically disable inverse-arp on DLCI learned from FR cloud but in question if this is not mentioned then we can use frame-relay interface-dlci 305 and 405 to map with R5 dynamically without using frame-relay inverse-arp feature.


so why INE workbook has given another solution for R3 and R4 to map with R5:-


R3#sh run int s1/0

interface serial1/0

ip address 155.1.200.3 255.255.255.0

encap frame

end

!

interface serial1/0.999

frame-relay interface-dlci 301

frame-relay interface-dlci 302

frame-relay interface-dlci 304


R4#sh run int s1/0


interface serial1/0

ip address 155.1.200.4 255.255.255.0

encap frame

end

!

interface serial1/0.999

frame-relay interface-dlci 401

frame-relay interface-dlci 402

frame-relay interface-dlci 403



i know that result is same with this INE solution but why about this solution and what is the meaning of this solution here?


as i know when we do provide ip add on main interface then it can send frame-relay inverse-arp massage to all remote router which learned via LMIs and make dynamic mapping with that and when we provide frame-relay interface-dlci <dst DLCI> on subinterface as well as provided ip address on main interface, in this condition it also can try to map with provided DLCI with interface-dlci command! right?

but according to this question R1 as destination is not responding to source as R3 with subinterface using interface-dlci 301 reason being R1 is already configured with no frame-relay inverse-arp ip 103 so on R3 is unable to make mapping with R1, R2 and R4 with this provided config.


please confirm me if i am wrong anywhere in this fully lengthy post!

and if u have any suggestion then please let me know!!!!







Comments

  • Hopefully i understood your issue and try to clarify.

     Inverse-arp is enabled on physical interface(which is multipoint in nature) and multipoint subinterfaces.

    Disabling inverse-arp, disables inverse-arp requests, but not inverse-arp replies

    By default all DLCI's are mapped to the main  physical interface, until you manually map it to certain subinterfaces with "frame-relay interface-dlci" command

    Inverse-arp requests are being send as soon as IP processing is enabled on the interface/subinterface(you have IP address configured) for all DLCI' mapped to that interface/subinterface. So if you have IP address configured on main interface and you assign DLCI 101 and DLCI 102 to a subinterface which does not have IP address configured, inverse-arp requests will NOT be send out for those two DLCI's.

    Let me know if it clarifies your issue.

  • To add just a bit to what Cristian wrote - when your router receives a frame-relay inverse-arp request, it will install a dynamic mapping of the IP address of the router that sent the request to the DLCI the request was received on, unless there is no IP address configured on the (sub-)interface the DLCI is assigned to, the DLCI is on a point-to-point sub-interface, or there already is a static mapping for that DLCI.

  • Hello ssfouzdar.ie 

     

    Christian has explain the frame-relay topic in a very easy way. I would like to add to watch the Brian ATC Frame-relay, he has taught it frame-relay fundamentals, Hope this would be very easy for you.

    Here is the URL

    http://www.ine.com/all-access-pass/training/playlist/ccie-routing-switching-advanced-technologies-class/frame-relay-212.html

     

    Happy Studying

  • hi cristian, thanks for this suggestion but if we dont send inverse-arp request for both DLCIs then why we are configuring in this way ?? we can directly map to destination with asigning frame-relay interface-dlci at subinterface and ip add on this subinterface as well.

    secondly, if we provide one ip address on main interface and same ip on its multipoint subinterface then it can send inverse-arp request to all DLCIs as well as specified DLCI into subinterface

  • I'm sorry but i don't understand your point. First, is it technology in general or particular to this task? Second, what is exactly that you don't understand?

    Good luck with your studies!


  • hi cristian, please go through my exact previous question once again

    task 3. is saying:-

     

    3. configure R3 and R4 to disable inverse-arp on DLCI learned from frame-relay cloud that are not listed in the diagram by asgining them to subinterface 999.

    so configuring this task we can do also which i did already and below is snap shot for this solution-------

     

     

    R3# sh run int s1/0.999 point-2-point

    interface Serial1/0.999 point-to-point

     ip address 155.1.200.3 255.255.255.0

     frame-relay interface-dlci 305

    end

    R4#sh run int s1/0.999 p

    interface Serial1/0.999 point-to-point

     ip address 155.1.200.4 255.255.255.0

     frame-relay interface-dlci 405

    end

    reason being need to disable inverse-arp on DLCIs learned from frame-relay clound but when i check that R5 is having right mapping with R1, R2, R3 and R4 and R1, R2, R3, R4 is also having right mapping with R5 as well as R1, R2, R3 and R4 is not having mapping each other such that:-

    R1# sh frame map

    Serial1/0 (up): ip 155.1.100.5 dlci 105(0x69,0x1890), dynamic,

                  broadcast,

                  CISCO, status defined, active

    R2#sh frame map

    Serial1/0 (up): ip 155.1.100.5 dlci 205(0xCD,0x30D0), dynamic,

                  broadcast,, status defined, active

    R3#sh frame map

    Serial1/0.999 (up): point-to-point dlci, dlci 305(0x131,0x4C10), broadcast

              status defined, active

    R4#sh frame map

    Serial1/0.999 (up): point-to-point dlci, dlci 405(0x195,0x6450), broadcast

              status defined, active

    i also know according this question R3 and R4 can not be configured with no frame-realy inverse-arp ip 301, 302 and 401, 402. so the only configuration can be possible here is done here with pont-2-point interface on R3 and R4 so would this be right for this task?

    if any other solution can be possible here then please confirm me with point-2-point!!

     

    now other way :- on R3 and R4 is having multipoint subinterfaces such as s1/0.888 multipoint

    we can configure static mapping on R3 and R4 with R5 so that it will automatically disable inverse-arp on DLCI learned from FR cloud but in question if this is not mentioned then we can use frame-relay interface-dlci 305 and 405 to map with R5 dynamically without using frame-relay inverse-arp feature.

     

     

    but INE workbook has given another solution for R3 and R4 to map with R5:-

     

    R3#sh run int s1/0

    interface serial1/0

    ip address 155.1.200.3 255.255.255.0

    encap frame

    end

    !

    interface serial1/0.999

    frame-relay interface-dlci 301

    frame-relay interface-dlci 302

    frame-relay interface-dlci 304

    R4#sh run int s1/0

    interface serial1/0

    ip address 155.1.200.4 255.255.255.0

    encap frame

    end

    !

    interface serial1/0.999

    frame-relay interface-dlci 401

    frame-relay interface-dlci 402

    frame-relay interface-dlci 403

     

    i know that result is same with this INE solution but why about this solution is valid not mine which i have configured above in this blog?

  • The post is quiet confusing in itself I guess... Sorry about this but it's 4:30 AM here and my Brain cell battery is down.

    Anyways.... format your post in following manner to avoid any confusions :

    1. Relavent Diagram/s

    2. Objective of the task

    3. Your solutio

    4. Query

     

    Now from prospective of taking a detailed look at inverse arp, refer rfc 2390.

     

    HTH...

    Deepak Arora

    http://deepakarora1984.blogspot.com

     

  • The purpose of 2.9 in INE R&S Volume 1 is to be able to SELECTIVELY use inverse-arp for certain DLCIs, while preventing undesired dynamic mappings on other DLCIs.

    The instructions are to assign any UNUSED DLCIs to a subinterface. Since more than one undesired DLCI will be learned, the subinterface must be MULTIPOINT.

    The goal is to have inverse-arp create the desired dynamic mappings, but no undesired mappings.

    I think the task could be worded a bit more clearly, but it does lead the candidate to the end result found in the Solution Guide.

    A task worded like this could be found on an actual CCIE R&S Lab Exam - pay close attention to the way each part is worded, and make sure your solution meets ALL requirements.

    Configuring the DLCIs on a subinterface with no IP address is one way of disabling inverse-arp. This will prevent your router from sending inverse-arp requests, because IP is not configured on the interface where the DLCI resides, and will prevent the router from responding to inverse-arp requests from another router on that DLCI, because IP is required to send the response.

    Using the "no frame-relay inverse-arp ip <DLCI>" can be used to prevent SENDING frame-relay inverse-arp REQUESTS, but will not prevent dynamic mappings when another router sends a frame-relay inverse arp request, which will cause your router to send a frame-relay inverse-arp RESPONSE, and to create a dynamic mapping if an IP address is configured on the interface, and no static mapping exists for IP over the DLCI.

    Your solution of creating a point-to-point subinterface and moving the desired DLCI and IP address to that subinterface does not satisfy the requirements of the task - the instructions were to assign the DLCIs NOT LISTED ON THE DIAGRAM to subinterface 999.

    3. configure R3 and R4 to disable inverse-arp on DLCI learned from frame-relay cloud that are not listed in the diagram by asgining them to subinterface 999.

    so configuring this task we can do also which i did already and below is snap shot for this solution-------

    R3# sh run int s1/0.999 point-2-point

    interface Serial1/0.999 point-to-point

     ip address 155.1.200.3 255.255.255.0

     frame-relay interface-dlci 305

    end

    R4#sh run int s1/0.999 p

    interface Serial1/0.999 point-to-point

     ip address 155.1.200.4 255.255.255.0

     frame-relay interface-dlci 405

    end

     

  • thanks darrellEscola for clearifying this task

    The purpose of 2.9 in INE R&S Volume 1 is to be able to SELECTIVELY use inverse-arp for certain DLCIs, while preventing undesired dynamic mappings on other DLCIs.

    The instructions are to assign any UNUSED DLCIs to a subinterface. Since more than one undesired DLCI will be learned, the subinterface must be MULTIPOINT.

    The goal is to have inverse-arp create the desired dynamic mappings, but no undesired mappings.

    I think the task could be worded a bit more clearly, but it does lead the candidate to the end result found in the Solution Guide.

    A task worded like this could be found on an actual CCIE R&S Lab Exam - pay close attention to the way each part is worded, and make sure your solution meets ALL requirements.

    Configuring the DLCIs on a subinterface with no IP address is one way of disabling inverse-arp. This will prevent your router from sending inverse-arp requests, because IP is not configured on the interface where the DLCI resides, and will prevent the router from responding to inverse-arp requests from another router on that DLCI, because IP is required to send the response.

    Using the "no frame-relay inverse-arp ip <DLCI>" can be used to prevent SENDING frame-relay inverse-arp REQUESTS, but will not prevent dynamic mappings when another router sends a frame-relay inverse arp request, which will cause your router to send a frame-relay inverse-arp RESPONSE, and to create a dynamic mapping if an IP address is configured on the interface, and no static mapping exists for IP over the DLCI.

    Your solution of creating a point-to-point subinterface and moving the desired DLCI and IP address to that subinterface does not satisfy the requirements of the task - the instructions were to assign the DLCIs NOT LISTED ON THE DIAGRAM to subinterface 999.

    3. configure R3 and R4 to disable inverse-arp on DLCI learned from frame-relay cloud that are not listed in the diagram by asgining them to subinterface 999.

    so configuring this task we can do also which i did already and below is snap shot for this solution-------

    R3# sh run int s1/0.999 point-2-point

    interface Serial1/0.999 point-to-point

     ip address 155.1.200.3 255.255.255.0

     frame-relay interface-dlci 305

    end

    R4#sh run int s1/0.999 p

    interface Serial1/0.999 point-to-point

     ip address 155.1.200.4 255.255.255.0

     frame-relay interface-dlci 405

    end

     

     

  • The DLCIs are configured on the Frame Relay switch. The FRS doesn't change between different labs.

  •  

    Looking at the "logical layer 3 diagram" I see DLCI 205,502,305,503,105,501,405,504,101.

    Can someone tell me where these DLCIs in the example answer are coming from?  Where's 102,103,104,113,201,203,204,213,401,402,403,413 coming from?

    Is the diagram I'm looking at not complete?

     

  • Like I said, all of those DLCIs are configured on the Frame Relay Switch. This doesn't change between labs. It lets you configure many logical topologies, without changing it. The problem with this is that the FRS will tell your router about those DLCIs, in addition to the ones you're actually using today.

    Your diagram probably only shows DLCIs relevant to the lab you're working on. Other labs will use different combinations of DLCIs. You can work out where they are mapped to from the numbers. Or look at the FRS config itself.

  • If you do a show frame PVC | I STATUS you'll see all the DLCIs that are being advertised to you from the frame switch.

    Sent from my iPhone

    On Mar 21, 2013, at 7:46 PM, rickychiu75 <[email protected]> wrote:


    Looking at the "logical layer 3 diagram" I see DLCI 205,502,305,503,105,501,405,504,101.

    Can someone tell me where these DLCIs in the example answer are coming from?  Where's 102,103,104,113,201,203,204,213,401,402,403,413 coming from?




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  • Wow.. thanks for that quick reply.  I'm doing most of this frame-relay in my head.  I had a decent idea on all this until I reach section 2.9.  I think there'a full mesh here that is not displayed in the diagram.

  • Look at the topology here: http://www.ine.com/topology.htm

    Remember, the physical topology and BB routers don't change between labs. So there's a lot of extra connections that are not used for any one specific lab - but because they're there, you can quickly change your logical topology.

  • I Think there is a miss on the workbook answer...CMIIW

    Question : Configure R3 and R4 to disable Inverse-ARP on DLCIs learned from the
    Frame Relay cloud that are not listed in the diagram by assigning them to
    the subinterface 999

    first , wrong ip address on R4...it should be ip address 155.1.200.4 255.255.255.0 on serial 0/0

    second, on R3 I run this command as folllow :

    R3#show frame pvc | i STATUS
    DLCI = 301, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0
    DLCI = 302, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0
    DLCI = 304, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0
    DLCI = 305, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1/0
    DLCI = 311, DLCI USAGE = UNUSED, PVC STATUS = ACTIVE, INTERFACE = Serial1/1
    DLCI = 312, DLCI USAGE = UNUSED, PVC STATUS = ACTIVE, INTERFACE = Serial1/1
    DLCI = 314, DLCI USAGE = UNUSED, PVC STATUS = ACTIVE, INTERFACE = Serial1/1
    DLCI = 315, DLCI USAGE = UNUSED, PVC STATUS = ACTIVE, INTERFACE = Serial1/1

    Conf t
     interface Serial1/0.999 multipoint
     frame-relay interface-dlci 301
     frame-relay interface-dlci 302
     frame-relay interface-dlci 304
     frame-relay interface-dlci 311
     frame-relay interface-dlci 312
     frame-relay interface-dlci 314
     frame-relay interface-dlci 315

    the last 4 commands must be included as a part of the solutions.

    but i'm thinking maybe INE does not put those 4 commands as a part of the solution because they were learned not from interface serial 1/0 that connecting R3 to the frame-relay cloud.

     

    Please someone can confirm this, so I can get the true answer to the question as I just start my CCIE Learning.

    Cheers,

    Yahya Laksana

     

     

  • Hi,

    In WB VOL1, R3 has two Frame-Relay connections. This task is explicitly referring to the FR connection on Serial1/0, so you don't have to issue the last 4 commands as you said, as those are learned over a different interface.

    HTH

    Good luck!

  • thanks for explanation given :)

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