From: Don Banyong (don_study@xxxxxxxxxxx)
Date: Mon Mar 04 2002 - 15:16:30 GMT-3
Hey....
Since you are in the same predicament as I was a couple of weeks ago, I will
help you out...
I have research this matter to the fullest.
There are two things to help you understand the basis of this matter.
1. Physical DCE/DTE (Layer 1 configuration).
2. Layer 2's concept of DCE/DTE and peer switch (NNI).
(See Fig 1 and 2 also -- In Fig 1 and 2, FR-SW stands for Frame-Relay Switch
which is the router doing the frame Relay switching)
When connecting two routers at the physical layer using a serial intf, one
of the routers are suppose to provide clocking for the signals. The clocking
source is usually the DCE (Layer 1 DCE) device. We know that in order to
make a router to provide clocking, we need to use the command 'CLOCK RATE
XXXX' where XXXX is the clock rate/speed. Also the INTF with this command
must have a the DCE side of the V.35 cable connected to it.
Every Frame Relay interface (a serial Intf with the command encapsulation
Frame-relay specified) can be of three different types referring to three
different configurations.
A Frame Relay intf can be a
1. DTE -- This intf type is for routers who are nodes (or DTEs... that is
they create and receive the end traffic) in a Frame Relay network. This is
the default Frame Relay intf type and does not appear in default configs.
But the first time you type the command 'encapsulation Frame-relay' in an
intf configuration mode, the command Frame-Relay Intf-type DTE is also
configured by default.
2. DCE -- This intf-type is for a router that has a particular interface
involved in frame-relay switching. Your Frame-relay switch should have this
command in every serial interface that does Frame-Relay switching.
It does not matter whether this intf is a layer 1 DTE or DCE!!!
(r1)(s1 - DTE) -----(s0 - DCE)(FR-SW)(s1 - DCE)----(s1 - DTE)(r2) <Fig1>
Remember .... the DCE or DTE specified here are all layer 2 configurations.
On routers r1 and r2, you will not see the command Frame-Relay Intf-Type DTE
because it is a default command.
3. NNI (Network 2 Network Interface) -- This intf-type is for a router that
does Frame-Relay switching and which has one of its intf connected to
another Frame-Relay switch.
(FR-SW)(s0 - NNI)-------------(s1 - NNI)(FR-SW2) < Fig 2>
So a Frame Relay switch may be a physical (layer1) DTE on one of its intf or
a layer1 DCE. This intf though will still have the Frame-Relay Intf-type
DCE command issued under it if it is involved in frame relay switching.
Be careful in your Lab... the Proctor might set up a frame-relay switch in
any manner...meaning the all layer 1 DCEs might not be at the FR-switch. You
need to know which of your serial interfaces is a layer 1 DTE and which one
is a layer 1 DCE. Use the command 'Show Controller Serial X' to see whether
a particular serial intf is a layer1 DTE or a DCE
Thanks
Don
----- Original Message -----
From: "Yigit Zorlu" <yigitzorlu@yahoo.com>
To: "'MERRILL, JAMES D (AIT)'" <jm8752@sbc.com>; "'Don Banyong'"
<don_study@hotmail.com>; "'kym blair'" <kymblair@hotmail.com>;
<johnspencer@planet.nl>; "'Hansang Bae'" <hbae@nyc.rr.com>;
<ccielab@groupstudy.com>
Sent: Saturday, March 02, 2002 8:54 AM
Subject: RE: Frame-Relay Intf-type DCE
> Hi all,
>
> I was digging the archieves and read mails about this topic. Now I have a
> question
>
> Which less frequently used command(s) may be required on the exam in FR
> interfaces ? By remembering that FR switch config. can not be modified...
> For example, in any case do we need to configure clockrate in the FR
> encapsulated serial interfaces of lab routers ? I dont think so since it
is
> a layer 1 requirement, it has to be configured on the interface where DCE
> end of the serial cable is attached which is FR switch. So they can not
ask
> that.
>
> But what if they configure the serial interfaces in the FR switch
> frame intf-type dte ???
>
> Dont we need to configure frame intf-type dce in our fr interfaces of
> routers ??
>
> Or can they ask a question like this ? I think it is technically
possible..
>
> Any comments ?
>
> yigit
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> MERRILL, JAMES D (AIT)
> Sent: Wednesday, February 13, 2002 6:03 PM
> To: Don Banyong; kym blair; johnspencer@planet.nl; Hansang Bae;
> ccielab@groupstudy.com
> Subject: RE: Frame-Relay Intf-type DCE
>
>
> The Frame-relay intf-type DTE is the default.
> The only time I've used this command was when I connected my frame switch
to
> a real frame cloud. The example on the doc CD has it as a hybrid solution
> were you connect to a frame switch but split PVCs off to other routers
that
> are connected by pt-to-pt connections.
>
> James D. Merrill
>
>
>
> -----Original Message-----
> From: Don Banyong [mailto:don_study@hotmail.com]
> Sent: Tuesday, February 12, 2002 4:13 PM
> To: kym blair; johnspencer@planet.nl; Hansang Bae;
> ccielab@groupstudy.com
> Subject: Re: Frame-Relay Intf-type DCE
>
>
> Hello y'all.
> I have am still not sure if we have learnt anything new here.
> Pasted below, is the config of my three routers r1, r3 and r4 connected to
a
> 2610 with three serial interfaces (two of which are syncronous smart
> serials). Pay attention to the physical (layer 1) DCE and DTE and also of
> the FR DCE intf.
>
> r1:
> hostname r1
> interface Serial0
> no ip address
> encapsulation frame-relay
> no keepalive
> clockrate 64000
> !
> interface Serial0.1 point-to-point
> ip address 172.16.0.1 255.255.255.252
> frame-relay interface-dlci 102
> !
> interface Serial1
> no ip address
> encapsulation frame-relay
> !
> interface Serial1.1 point-to-point
> ip address 172.16.96.1 255.255.255.252
> frame-relay interface-dlci 104
> !
> interface Serial1.2 point-to-point
> ip address 172.16.64.1 255.255.255.252
> frame-relay interface-dlci 103
> end
>
> r3:
> !
> interface Serial0.1 point-to-point
> ip address 172.16.64.2 255.255.255.252
> no cdp enable
> frame-relay interface-dlci 301
> !
> interface Serial0.2 point-to-point
> ip address 172.16.80.2 255.255.255.252
> no cdp enable
> frame-relay interface-dlci 304
> !
> interface Serial1
> no ip address
> shutdown
> no cdp enable
> end
>
> r4:
>
> interface Serial0
> no ip address
> encapsulation frame-relay
> no ip route-cache
> no ip mroute-cache
> clockrate 64000
> !
> interface Serial0.1 point-to-point
> ip address 172.16.96.2 255.255.255.252
> no ip route-cache
> frame-relay interface-dlci 401
> !
> interface Serial0.2 point-to-point
> ip address 172.16.80.1 255.255.255.252
> frame-relay interface-dlci 403
> no ip route-cache
> end
>
> fr-ts(frame-relay switch):
> interface Serial0/0
> no ip address
> no ip directed-broadcast
> encapsulation frame-relay
> clockrate 64000
> frame-relay intf-type dce
> frame-relay route 103 interface Serial0/2 301
> frame-relay route 104 interface Serial0/1 401
> !
> interface Serial0/1
> no ip address
> no ip directed-broadcast
> encapsulation frame-relay
> frame-relay intf-type dce
> frame-relay route 401 interface Serial0/0 104
> frame-relay route 403 interface Serial0/2 304
> !
> interface Serial0/2
> no ip address
> no ip directed-broadcast
> encapsulation frame-relay
> clockrate 64000
> frame-relay intf-type dce
> frame-relay route 301 interface Serial0/0 103
> frame-relay route 304 interface Serial0/1 403
> end
>
> When cmd 'sh frame route' is issued on my frame-relay switch, the output
is
> Input Intf Input Dlci Output Intf Output Dlci Status
> Serial0/0 103 Serial0/2 301 active
> Serial0/0 104 Serial0/1 401 active
> Serial0/1 401 Serial0/0 104 active
> Serial0/1 403 Serial0/2 304 active
> Serial0/2 301 Serial0/0 103 active
> Serial0/2 304 Serial0/1 403 active
>
> I should mention also that there is full connectivity between all three
> routers (r1, r3 and r5 configured for full-mesh) verified by ping.
> As noticed, the fr-ts router(frame relay switch) has command 'frame-relay
> intf-type dce' on all three serial intfs even though its interface
Serial0/1
> is a DTE. Cisco also has a similar example on their website.
> Again the question is when do you use the command 'frame-relay intf-type
> DTE' command?
>
> Thanks.
> Don
>
>
>
>
>
> ----- Original Message -----
> From: "kym blair" <kymblair@hotmail.com>
> To: <johnspencer@planet.nl>; <hbae@nyc.rr.com>; <ccielab@groupstudy.com>
> Sent: Sunday, February 10, 2002 6:31 AM
> Subject: Re: Frame-Relay Intf-type DCE
>
>
> > Hansang,
> >
> > I sometimes use "frame intf-type dte" on my Frame Relay switch.
> >
> > Most of the time I use a 2520 for my frame switch, and I put the DCE end
> on
> > the frame switch. But when I use my 2600 with WIC-2T modules for my
frame
> > switch, my smart-serial-to-DB60 cables have the DTE on the smart-serial
> end,
> > which I must attach to the 2620. Because of these cables, I have to
make
> my
> > frame switch the DTE. The command is available and I use it with no
> > problem.
> >
> > HTH, Kym
> >
> >
> > >From: "John Spencer" <johnspencer@planet.nl>
> > >Reply-To: "John Spencer" <johnspencer@planet.nl>
> > >To: "Hansang Bae" <hbae@nyc.rr.com>, <ccielab@groupstudy.com>
> > >Subject: Re: Frame-Relay Intf-type DCE
> > >Date: Sun, 10 Feb 2002 11:42:48 +0100
> > >
> > >Here is a situation when you can use both frame intf-type dte and dce
on
> > >the
> > >"frame relay switch"
> > >
> > >Lets say you have a 3640 or whatever. You create the frame relay routes
> > >(switching paths ) from one interface to another eg serial 0/1 dlci 100
> to
> > >ser 1/0 dlci 110. Now what usually happens is you run from the
interface
> > >which is usually dce physical and intf-type dce to another router. But
> > >instead you take a back to back cable and loop it between ser1/0 to say
> ser
> > >2/0 on the same router. Serial 2/0 now becomes the endpoint with ip
> > >addresses and the termination point of the circuit. Here is where you
> would
> > >use frame-relay intf-type dte. Although it apparently should not make a
> > >difference, in practice i would match physical and intf-type dce and
dtes
> > >together as I have found it can make a difference.
> > >
> > >Regards
> > >John Spencer
> > >
> > >----- Original Message -----
> > >From: "Hansang Bae" <hbae@nyc.rr.com>
> > >To: <ccielab@groupstudy.com>
> > >Sent: Saturday, February 09, 2002 6:46 AM
> > >Subject: Re: Frame-Relay Intf-type DCE
> > >
> > >
> > > > At 11:51 PM 2/8/2002 -0500, Don Banyong wrote:
> > > > >You still did not answer my question. I completely understand the
> layer
> > >1
> > > > >concept of DCE and DTE.
> > > > >My question is -- in which scenario can someone use the Frame-relay
> > > > >Intf-type DTE command ?
> > > >
> > > >
> > > > When you hook up your router to a frame relay switch. This is the
> > >default
> > > > state. Type it in and you will not see it.
> > > >
> > > > hsb
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