From: Pedro Eira (pdaeira@hotmail.com)
Date: Mon Mar 03 2003 - 11:01:48 GMT-3
So what split-horizon changes would you do if there are two different FR
clouds, and all interfaces are physical, & running RIP?
1-------FR------2-------FR-------3
Would you turn split-horizon on 1 & 3, since they are considered as
spokes?
>From: "OhioHondo" >Reply-To: "OhioHondo" >To: "Connie Nie" , , >Subject:
RE: Split-horizon mystery >Date: Fri, 28 Feb 2003 15:31:00 -0500 > >Brian
> >Just for my own clarification I'm going to try to summarize what I
think is >your input on this string -- and maybe ask for a clarification.
> >Split Horizon is only applied at the interface level. > >The setting
of split horizon is specific to the interface or sub-interface >on which
it is applied. > >Split Horizon is only used with IGP's (RIP, IGRP,
EIGRP). > >Split Horizon only applies to routing updates. > >Both
RIP/IGRP and EIGRP Split Horizon are on by default. > >There are two
types of Split Horizon. > RIP and IGRP use the interface command "ip
split-horizon". > EIGRP uses the command "ip split-horizon eigrp XXX" >
>It is not clear as to whether both of these can co-exist on the same
>interface but since you can run RIP and EIGRP on the same interface it
is >logical that you can. > >You can monitor the setting of split horizon
for RIP or IGRP using "sho ip >int". If you config "no ip split" it shows
up in the config file. > >I don't believe anyone has come up with how we
can monitor the setting of >split horizon for EIGRP. If you config "no ip
split eigrp XX" it shows up in >the config file. > >Split Horizon should
probably only be disabled on interfaces that are hubs >to two or more
spokes. If it is not disabled, routing updates from one spoke >will not
be propagated to the other spokes. > >-----Original Message----- >From:
nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of >Connie
Nie >Sent: Friday, February 28, 2003 10:14 AM >To:
ccielab@groupstudy.com; 'brian@cyscoexpert.com' >Subject: RE:
Split-horizon mystery > > >Brian, > >Can you elaborate a little bit on
the effect of IP split-horizon and eigrp >split-horizon if used together?
If I have a hub interface with ip >split-horizon enabled but eigrp
split-horizon disabled, then the routed >traffic will observe
split-horizon rule but routing traffic will not---do I >understand it
correctly? If that is the case then the spoke will have a >route for the
other spoke, but won't receive any traffic from the other >spoke. I guess
my question is how do these two work together? > >Thank you very much. >
>Connie > >-----Original Message----- >From: Brian McGahan
[mailto:brian@cyscoexpert.com] >Sent: Friday, February 28, 2003 1:11 AM
>To: 'OhioHondo'; 'Brian Dennis'; 'Hunt Lee'; 'Jim Brown' >Cc:
ccielab@groupstudy.com >Subject: RE: Split-horizon mystery > >IP split
horizon and EIGRP split horizon are independent of each other. >EIGRP
split horizon is always on unless you disable it. You can disable >IP
split horizon, and leave EIGRP split horizon on, and vice versa. > >As
Brian mentioned, sub-interfaces count as different logical entities, >so
you could have IP or EIGRP split horizon disabled on one and enabled >on
the other. To check if IP split horizon is on, use the 'show ip
>interface [int]' command. > >HTH > >Brian McGahan, CCIE #8593 >Director
of Design and Implementation >brian@cyscoexpert.com > >CyscoExpert
Corporation >Internetwork Consulting & Training >Toll Free: 866-CyscoXP
>Outside US: 847.674.3392 >Fax: 847.674.2625 > > > > -----Original
Message----- > > From: nobody@groupstudy.com
[mailto:nobody@groupstudy.com] On Behalf >Of > > OhioHondo > > Sent:
Thursday, February 27, 2003 9:40 PM > > To: Brian Dennis; 'OhioHondo';
'Hunt Lee'; 'Jim Brown' > > Cc: ccielab@groupstudy.com > > Subject: RE:
Split-horizon mystery > > > > Brian > > > > Do you know how to check if
EIGRP Split Horizon is set? > > > > It is possible to set split horizon
and ip eigrp split horizon >separately. > > > > Setting split horizon
seems to manipulate the value shown in "sho ip >int". > > > > > >
-----Original Message----- > > From: Brian Dennis
[mailto:brian@labforge.com] > > Sent: Thursday, February 27, 2003 9:25 PM
> > To: 'OhioHondo'; 'Hunt Lee'; 'Jim Brown' > > Cc:
ccielab@groupstudy.com > > Subject: RE: Split-horizon mystery > > > > > >
Normally you aren't processing IP on the major interface if you are > >
using sub-interfaces so anything relating to split-horizon on the >major
> > interface has nothing to do with the sub-interface. > > > >
Rack4R3#sho ip int | include (Serial)|(Split) > > Serial1/0 is up, line
protocol is up > > Serial1/0.32 is up, line protocol is up > > Split
horizon is enabled > > Serial1/0.243 is up, line protocol is up > > Split
horizon is enabled > > Rack4R3#sho ip int s1/0 > > Serial1/0 is up, line
protocol is up > > Internet protocol processing disabled > > Rack4R3# > >
> > Brian Dennis, CCIE #2210 (R&S/ISP Dial/Security) > >
brian@labforge.com > > http://www.labforge.com > > > > -----Original
Message----- > > From: nobody@groupstudy.com
[mailto:nobody@groupstudy.com] On Behalf >Of > > OhioHondo > > Sent:
Thursday, February 27, 2003 5:36 PM > > To: Hunt Lee; 'Jim Brown' > > Cc:
ccielab@groupstudy.com > > Subject: RE: Split-horizon mystery > > > >
Hunt/Jim > > > > I believe that split horizon on an interface works for
the entire >MAJOR > > interface. If you have applied split horizon
applied to an interface >it > > applies to all of the sub-interfaces on
that MAJOR interface. > > > > I know that you can apply "ip split eirgp
xx" directly on a > > sub-interface, > > but does it then only apply to
that sub-interface? > > > > -----Original Message----- > > From:
nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of > > Hunt
Lee > > Sent: Thursday, February 27, 2003 6:10 PM > > To: 'Jim Brown' > >
Cc: 'ccielab@groupstudy.com' > > Subject: RE: Split-horizon mystery > > >
> > > Hi Jim, > > > > That's kinds of fall into what I was thinking...
hence the answer to >my > > lab > > scenario would be wrong?? Since the
EIGRP is only running on a > > point-to-point network here? > > > > Or am
I completely off? > > > > Thanks in advance, > > > > Regards, > > Hunt >
> > > > > -----Original Message----- > > From: Jim Brown
[mailto:Jim.Brown@caselogic.com] > > Sent: Friday, 28 February 2003 1:48
AM > > To: Hunt Lee; ccielab@groupstudy.com > > Subject: RE:
Split-horizon mystery > > > > > > Think about what split horizon is.... >
> > > Split horizon basically keeps a router from advertising a route out
>the > > interface it learned the route from. Most of the time this is
the > > desired behavior, but in the case of a multipoint interface it
might >not > > be. > > > > If the spokes are advertising routes to the
hub and the hub has split > > horizon enabled, it will not advertise
routes from one spoke to >another > > if they are on the same interface.
> > > > Split horizon only affects DV protocols and to disable it for
EIGRP >you > > must use a different command than other DV protocols. The
command is >no > > ip split-horizon eigrp while all other DV protocols us
the >command > > no ip split-horizon. > > > > You can also use show ip
interface to determine the status of split > > horizon on an interface. >
> > > -----Original Message----- > > From: Hunt Lee
[mailto:huntl@webcentral.com.au] > > Sent: Thursday, February 27, 2003
12:20 AM > > To: 'ccielab@groupstudy.com' > > Subject: Split-horizon
mystery > > > > > > Hi Group, > > > > Does anyone know when one should
use "ip split-horizon" for EIGRP? > > > > RTD > > / > > RTA---- RTB > > \
> > RTC > > > > RTA, RTB & RTD are using OSPF, while RTA & RTC are both
using EIGRP... > > > > RTA & RTC are point-to-point, while.. > > > > RTA,
RTB & RTD are point-to-multipoint > > > > On the solutions, I was told
that I need to use "ip split-horizon" on > > RTC > > outgoing interface
(to RTA), why??? I thought we only need to use >this > > command on the
hub if it is point-to-multipoint sub-interface... > > > > anyway, here's
the config:- > > > > On RTC:- > > > > interface Serial0 > > ip address
137.20.200.18 255.255.255.240 > > ip nat outside > > encapsulation
frame-relay > > ip split-horizon <------ Do we need this??? > > no ip
mroute-cache > > keepalive 15 > > no fair-queue > > frame-relay lmi-type
ansi > > > > > > router eigrp 10 > > network 137.20.0.0 > > no
auto-summary > > > > > > And on RTA:- > > > > interface Serial0.1
multipoint > > ip address 137.20.100.34 255.255.255.224 > > ip ospf
network point-to-multipoint > > frame-relay de-group 1 502 > >
frame-relay map ip 137.20.100.33 502 broadcast > > frame-relay map ip
137.20.100.35 503 broadcast > > ! > > interface Serial0.2 point-to-point
> > bandwidth 2000 > > ip address 137.20.200.17 255.255.255.240 > >
frame-relay interface-dlci 504 > > > > router eigrp 10 > > redistribute
ospf 10 metric 2000 100 255 1 1500 > > passive-interface BRI0 > >
passive-interface Ethernet0 > > passive-interface Serial0.1 > >
passive-interface Serial1 > > network 137.20.0.0 > > no auto-summary > >
no eigrp log-neighbor-changes > > > > > > Any help / ideas would be
greatly appreciated. > > > > Regards, > > Hunt
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