From: ccie2be (ccie2be@nyc.rr.com)
Date: Fri Jul 15 2005 - 15:38:12 GMT-3
Thanks. That explanation from alliance was much better than anything I've
seen on cisco.
-----Original Message-----
From: Godswill Oletu [mailto:oletu@inbox.lv]
Sent: Friday, July 15, 2005 1:37 PM
To: ccie2be; 'jellyboy'; ccielab@groupstudy.com
Subject: Re: Back-to-Back FR
Tim,
The DOC CD, did not bring out the distinction very well, but read the
following:
Compare Doc CD's explaination below, with the one offerred by
alliancedatacom, you will notice a difference is the details:
Doc CD:
http://www.cisco.com/univercd/cc/td/doc/cisintwk/itg_v1/tr1918.htm#1020754
Alternative1:
If you can't read the whole section, click on "Verify that the PVCC status
is active"
http://www.alliancedatacom.com/manufacturers/cisco-systems/framerelay_design
/framerelay_troubleshooting.asp#Step%203:
Alternative2:
If you do not have the time to read all the section, goto the site below,
click on Edit on your browser and then Find "The PVC can have four possible
states" without the quotes.
http://www.alliancedatacom.com/cisco-configuring-troubleshooting-frame-relay
.asp
You might come out with a different conclusion, but if you think through it
very well, that is the scenerio that is being painted.
Thanks.
----- Original Message -----
From: "ccie2be" <ccie2be@nyc.rr.com>
To: "'Godswill Oletu'" <oletu@inbox.lv>; "'jellyboy'" <jellyboy@gmail.com>;
<ccielab@groupstudy.com>
Sent: Friday, July 15, 2005 12:10 PM
Subject: RE: Back-to-Back FR
> Godswill,
>
> What an excellent post !!!
>
> I'm not sure if I ever heard those explanations before regarding "Deleted"
> and "Inactive" or I just forgot exactly what they meant.
>
> I knew in either case, I had a problem that needed to be fixed. Are those
> explanations hiding somewhere on the Doc-CD?
>
> And, are you 100% sure those meanings are correct? I don't have access to
> equipment at the moment otherwise I would test that out myself.
>
> TIA, Tim
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Godswill Oletu
> Sent: Friday, July 15, 2005 11:08 AM
> To: jellyboy; ccielab@groupstudy.com
> Subject: Re: Back-to-Back FR
>
> Jelly,
>
> Let me see if I can give this a shot.................
>
> To fully understand the reason, you have to step back a little and think
> through the frame relay technology a bit....
>
> When a router configured for frame relay boots up, it sends an LMI packet
> to
>
> the frame relay switch, the frame relay switch will response to the router
> and also make available to the router the various dlci numbers that can be
> reached via that interface. If the router is using in inverse arp, it will
> automatically obtain those dlci numbers and do all the mappings itself,
> but
> if inverse arp is disable, the router will use the dlci configured either
> on
>
> the 'frame-relay map' or on the 'frame-relay interface-dlci' statement. If
> the value of the dlci configured on the router is the same with what the
> switch have, your pvcs status will be 'active' and meaning your layer 2
> stuff are good.
>
> If the dlci configured locally and the frame relay switch is sending are
> not
>
> the same, you will get 'deleted' or 'inactive' status if you view your
> pvc.
> Deleted, is the frame relay switch telling you that, the dlci you
> configured
>
> on your router might be wrong, Inactive is saying the dlci configured on
> the
>
> remote side might be wrong.
>
> Now, you can see the role of the frame relay switch and LMI, now when you
> connect two routers back-to-back and do frame-relay encapsulation, the
> first
>
> thing both of them will do is send LMI to the frame relay switch, both
> router will keep waiting for a frame relay switch, so that they can
> negotiate layer 2 stuff, since none of the routers is a frame relay
> switch,
> your layer 2 will not get setup and your frame relay link will not come
> up,
> to resolve this problem, you have to disable LMI on both routers. eg
>
> R1#no keepalive
>
> Now, you have disable LMI communication between both routers, but you must
> find a way of telling each router what the data link CONNECTION IDENTIFIER
> (dlci) is? Think of a connection identifier as a logical path between both
> routers, if each router have a different path, the frame relay will be
> there
>
> to switch traffic from one path to the other, but in the absence of a
> frame
>
> relay switch, each router must be communicating on the same path, for them
> to hear each other talk, that one and only path can only be defined by
> giving both router the same DLCI number.
>
> So, with this setup, once the routers comes on, LMI disable, no looking
> for
> frame relay switch, R1 will automatically start talking via the path (DLCI
> #) configured on it, believing that someone will hear him, lucky enough we
> have equally tricked R2 to believe that that path (DLCI #) belong to him,
> so
>
> he will listen and response.
>
> Have you bridged (hardware not software) telephone extensions wiring
> closet
> or at home before....:) ...Thats exactly what I am talking about, all the
> bridged handset will have the same telephone ext. number eg ext 111. If
> someone in room 1, pickes up a bridged handset 1, he can easily talk to
> the
> second bridged handset in room 2, on the same ext 111, without dialing a
> different ext. number.
>
> I hope this helped a little bit.
>
> Others are free to comment, add, delete, refine, etc
>
> my 0.2
>
> ----
> Godswill Oletu
>
>
> ----- Original Message -----
> From: "jellyboy" <jellyboy@gmail.com>
> To: <ccielab@groupstudy.com>
> Sent: Friday, July 15, 2005 6:04 AM
> Subject: Back-to-Back FR
>
>
>> Hi, I have a number of questions regarding Back-to-Back FR. Two
>> routers R1 and R3 connected together with no FR switch in between.
>>
>> R3 config
>>
>> frame-relay switching
>> !
>>
>> interface Serial0/1
>> no ip address
>> encapsulation frame-relay
>> clockrate 56000
>> frame-relay intf-type dce
>> !
>> interface Serial0/1.31 point-to-point
>> des to r1 circuit
>> ip address 172.16.31.2 255.255.255.252
>> frame-relay interface-dlci 31<<must be same on both sides
>>
>> R1 config
>>
>> interface Serial0/3.31 point-to-point
>> des to r3 circuit
>> ip address 172.16.31.1 255.255.255.252
>> frame-relay interface-dlci 31<<must be same on both sides
>>
>> Question- why do the dlci values have to be the same value on both sides?
>> Question- does anyone know of any other configs that would achieve the
>> same result?
>>
>> Just curious, as usual!
>>
>> Cheers,
>>
>>
>> jellyboy
>>
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>
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