Re: no sending eigrp update

From: Bob Sinclair (bsin@cox.net)
Date: Tue Mar 29 2005 - 16:33:25 GMT-3


Tim,

Having captured and debugged the various scenarios with EIGRP neighbors and
passive interfaces, I believe I can confirm your understanding: EIGRP passive
interfaces will not form neighbors. They do not send hellos and will not
accept them from others. With neighbor statements, all updates and hellos are
unicast. The passage cited from the config guide is not necessarily
contradictory. It only says that the neighbor-passive command permits control
of neighboring on a LAN.

Without passive or neighbors, all EIGRP routers in the same AS on a LAN would
form neighbors. If some EIGRP routers on the link should not form
adjacencies, you can make them passive. Using neighbors, you can make routers
1,2 and 3 adjacent, and routers 4,5 and 6 adjacent, even if all are on the
same LAN and in the same AS.

HTH,

Bob Sinclair
CCIE #10427, CCSI 30427, CISSP
www.netmasterclass.net

  ----- Original Message -----
  From: ccie2be
  To: 'Dillon Yang'
  Cc: 'Group Study'
  Sent: Tuesday, March 29, 2005 11:40 AM
  Subject: RE: no sending eigrp update

  Hmmm, that seems to contradict my first point. Looks like this needs to be
  put to the test.

  -----Original Message-----
  From: Dillon Yang [mailto:gzdillon@hotmail.com]
  Sent: Tuesday, March 29, 2005 10:28 AM
  To: ccie2be
  Cc: Group Study
  Subject: Re: no sending eigrp update

  Hi,

    I agree too. But, how about this:
  http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_command_ref
e
  rence_chapter09186a008010a39a.html#wp1042007,
  <quote>
  Usage Guidelines
  This command permits the point-to-point (nonbroadcast) exchange of routing
  information. When used in combination with the passive-interface router
  configuration command, routing information can be exchanged between a
subset
  of routers and access servers on a LAN.
  </quote>

  best regards
  dillon

  ----- Original Message -----
  From: "ccie2be" <ccie2be@nyc.rr.com>
  To: "'Dillon Yang'" <gzdillon@hotmail.com>; "'mani poopal'"
  <mani_ccie@yahoo.com>
  Cc: "'Group Study'" <ccielab@groupstudy.com>
  Sent: Tuesday, March 29, 2005 11:17 PM
  Subject: RE: no sending eigrp update

> Dillon,
>
> The passive command is very funky. It works in different ways depending
  on
> the IGP.
>
> With eigrp:
>
> It stops hello packets so no adjacency can be formed with any neighbors
  out
> that interface. The neighbor command doesn't override this behavior.
  (So,
> even if unicast update packets were sent by using the neighbor (and I
  don't
> know if they are), it wouldn't matter because there won't be any
  adjacency.)
>
> With rip:
>
> It stops broadcast and multicast updates but doesn't stop unicast
updates.
> So, to send only unicast updates use both the passive and neighbor
  command.
>
> With ISIS:
>
> It injects the ip addr of that interface into the isis routing process
but
> also stops adjacencies out the specified interface.
>
> HTH, Tim
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Dillon Yang
> Sent: Tuesday, March 29, 2005 1:10 AM
> To: mani poopal
> Cc: Group Study
> Subject: Re: no sending eigrp update
>
> Hi, mani:
>
> I remember scott said that " passive" and " neighbor" are mutually bad
  for
> neighborhood, but are they also, "passive" and "network"?
>
> TIA
> dillon
>
>
> ----- Original Message -----
> From: "mani poopal" <mani_ccie@yahoo.com>
> To: "Dillon Yang" <gzdillon@hotmail.com>; "Group Study"
> <ccielab@groupstudy.com>
> Sent: Tuesday, March 29, 2005 1:45 PM
> Subject: Re: no sending eigrp update
>
>
> > Hi Dillon,
> >
> > In eigrp, you cannot use passive interface command, this command will
> prevent adjacency formation with the neighbor. Only 2 solutions exists
> > 1.distribute-list 101 out s 0
> > access-list 101 deny ip any any
> >
> > 2.eigrp stub receive-only
> >
> > Mani
> >
> > Dillon Yang <gzdillon@hotmail.com> wrote:
> > Hi, group:
> >
> > At 911network, a Task: not to send eigrp updates from your pod (Rx) to
  the
> backbone but you must be able to recieve routes from the bb:
> >
> > router eigrp 10
> > distribute-list 10 out e0/0
> > access-list 10 deny any
> >
> > I think the following config is ok, too:
> >
> > router eigrp 10
> > passsive default
> > network 0.0.0.0 255.255.255.255
> >
> > Any advice?
> >
> > TIA
> > dillon
> >
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