From: Chua, Parry (Parry.Chua@xxxxxxxxxx)
Date: Mon Nov 05 2001 - 04:15:20 GMT-3
Hi,
When you create a p2p sub interface, it behave like a orginal physical
serial interface, ie
sp is enabled. Looking at your topology, it is NOT a fully mesk FR, you must
ensure that
spoke can reach the other spoke. In typical case, you make use of
spoke->hub->spoke for layer 2 reachability. Each router must has a path to
other router.
Next is the routing update(layer 3). From your topology, sp must be enable
on hub and usually should be disable on spoke. Reason is hub has to act upon
for the spoke to pass the routing update, for example, update send from R2
should receive by R1, R3 to R6, the path from R2 routing update send to
R1(hub), later R1(hub) should forward this update to R3...R6. R1 using one
(common) interface to reach R2 to R6, if sp is enable, it will not forward
the update learn from R2 to R6 out from the same interface.( of course if
you create multiple sub interface at R1 will resolve this problem but it
also mean you has to create seperate subnet).
What will happen is route update send from R2 to R6 will be send back to
then again with additional hop count. You can control by filtering if
necessary. If sp is diable on R2 to R6
( default FR on main intercface), then you should enable SP on spoke router
to prevent it from sending unnecessary update back to R1.
> Parry Chua
> COMPAQ Computer Asia Pte Ltd
> Customer Services - APD
> Tel : +65-395-1856
> Fax : +65-3951878
> Email : parry.chua@compaq.com
>
>
-----Original Message-----
From: Brad Caplan [mailto:bradcaplan@yahoo.com]
Sent: Monday, November 05, 2001 2:45 PM
To: Chua, Parry; ccielab@groupstudy.com
Subject: RE: Basic Frame Relay, RIP, and Split Horizon Question
There is connectivity to all serial interfaces. R1 can
ping all spokes and vice versa. Unfortunately, I can't
seem to get RIP to advertise the ethernet interface
network addresses. All spokes can ping the ethernet
interface of R1, but not the ehternet interfaces of
the other spokes.
It seems like the problem is a split horizon issue
whereby R1 is not forwarding the spoke ethernet
network addresses. I can get it to work if I use sub
interfaces (point-to-point) but am wondering if there
is any other way.
Brad
--- "Chua, Parry" <Parry.Chua@compaq.com> wrote:
> Hi,
>
> You need to verify the datalink(layer2) reachability
> first using network
> layer address to verify. From your topology, it is
> assume that R1 is the
> hub, R2 to R6 are spokes. It is assume that R1 has 5
> dlci to reach R2 to R6.
> It is assume that R2 to R6 each has one dlci and can
> only reach R1. The
> first step you need to do is to ensure that R1(hub)
> can ping (spokes)R2 to
> R6 and vice versa. Next you need to verify R2 to R6
> (spoke to spoke). Afther
> this is done.
> Next it what routing protocols to run in this cloud,
> each has problem to
> resolve.
>
>
>
> > Parry Chua
> >
>
>
> -----Original Message-----
> From: Brad Caplan [mailto:bradcaplan@yahoo.com]
> Sent: Monday, November 05, 2001 9:57 AM
> To: ccielab@groupstudy.com
> Subject: Basic Frame Relay, RIP, and Split Horizon
> Question
>
>
> I have a Hub and Spoke configuration setup as
> follows:
>
> R1------FR-------R2
> |
> --------R3
> |
> --------R5
> |
> --------R6
>
> All of the router's serial connections are in the
> 10.1.1.x/24 network. Each router's ethernet
> connection
> is in a different class A network. Each router is
> running RIP.
>
> I can only ping the LAN interfaces of all
> routers if I use point-to-point subinterfaces on the
> spoke routers.
>
> Is it possible to achieve this same connectivity
> without using sub-interfaces? I tried using the 'no
> ip
> split-horizon' command on the serial interface of
> the
> hub router, (R1) but that does not seem to help.
>
> Thanks,
> Brad
>
>
>
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