[c-nsp] Help with multilink ppp, routing not working correctly..

[Howard Leadmon]

   Hello Diogo,

 Thanks for the reply.. Actually I had a dynamic routing protocol running on
the routers, and even pulled that and tried using static routes.   Actually
as I was just trying to ping interface to interface, no routing at all
should have been needed, as Router-B would have seen both of the /30's as a
connected path.

 Not sure if you saw my earlier response to Gert, but I did afterwards take
and tear down the MLPPP bundle, and then just put the /30 from the bundle on
a single T1 interface.  When I did that, everything worked, traffic moved
perfectly.  So it's without a doubt something very specific to having the
Multilink interface up, as only then does the pathway fail.  The only thing
I can see different when I put it over multilink is that I see a /30 and a
/32 in the routing table from it.  So if I am on router B and do a show ip
route, I see 192.168.98.28/30 and also a 192.168.98.30/32 both pointing to
the Multilink1 interface.   Not quite sure why I get that /32 in the table,
but guessing it's just a quirk of how the MLPPP connection establishes.



---
Howard Leadmon 


> -----Original Message-----
> From: Diogo Montagner [mailto:diogo.montagner at gmail.com]
> Sent: Saturday, July 19, 2008 8:25 PM
> To: Howard Leadmon
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] Help with multilink ppp, routing not working
> correctly..
> 
> Hi Howard,
> 
> If your configuration is all here then you need a static route in B
> router pointing to C.
> 
> Regards,
> ./diogo -montagner
> 
> 
> On Fri, Jul 18, 2008 at 8:18 PM, Howard Leadmon <howard at leadmon.net>
> wrote:
> >
> >  I can't believe this one isn't working, I am sure I am looking over
> > something stupid.  I needed to mux up 3x T1's between a location.
> >
> >
> > Information is as follows: (relevant bits)
> >
> > Location-A:   Cisco 1720
> > !
> > interface Serial0
> >  description To Location-B
> >  ip address 38.103.8.238 255.255.255.252
> > !
> > ip route 0.0.0.0 0.0.0.0 38.103.8.237
> > !
> >
> >
> >
> >
> > Location-B:  Cat5500 RSM
> > !
> > interface Multilink1
> >  description T1 MultiLink PPP Bundle to Location-C
> >  ip address 192.168.98.29 255.255.255.252
> >  ppp multilink
> >  multilink-group 1
> > !
> > interface Serial1/2:1
> >  description To Location-A
> >  ip address 38.103.8.237 255.255.255.252
> > !
> > interface Serial1/5:1
> >  description T1 3 of 3 (MultiLink)
> >  no ip address
> >  encapsulation ppp
> >  ppp multilink
> >  multilink-group 1
> > !
> > interface Serial1/6:1
> >  description T1 2 of 3 (MultiLink)
> >  no ip address
> >  encapsulation ppp
> >  ppp multilink
> >  multilink-group 1
> > !
> > interface Serial1/7:1
> >  description T1 1 of 3 (MultiLink)
> >  no ip address
> >  encapsulation ppp
> >  no fair-queue
> >  ppp multilink
> >  multilink-group 1
> > !
> > ip route 0.0.0.0 0.0.0.0 to global internet gateway!
> >
> >
> >
> > Location-C: Cisco 6509 Sup2 w/FlexWan
> > !
> > interface Multilink1
> >  description T1 Bundle to Corporate
> >  ip address 192.168.98.30 255.255.255.252
> >  ppp multilink
> >  multilink-group 1
> > !
> > interface Serial3/0/0:0
> >  description T1 1 of 3 no ip address
> >  encapsulation ppp
> >  no fair-queue
> >  ppp multilink
> >  multilink-group 1
> > !
> > interface Serial3/0/1:0
> >  description T1 2 of 3
> >  no ip address
> >  encapsulation ppp
> >  ppp multilink
> >  multilink-group 1
> > !
> > interface Serial3/0/2:0
> >  description T1 3 of 3
> >  no ip address
> >  encapsulation ppp
> >  ppp multilink
> >  multilink-group 1
> > !
> > ip route 0.0.0.0 0.0.0.0 192.168.98.29
> > !
> >
> >
> >
> > The interfaces are up and running, the multilink bundle looks good,
> and if I
> > ping or trace from A to B, or B to A life is good.   If I try and go
> from B
> > to C or C to B, again life is good.   If I try and go from A to the
> internet
> > via B, or from C via B to the internet all is good.  So it looks like
> all is
> > working.
> >
> > Where I get bit, is if I try and go from A to C, or C to A.  I can
> not ping,
> > and if I trace it dies on router B.   So it looks like single hop is
> good,
> > and if I go to another location out off of B (other networks) all is
> good,
> > but if I try and cross any other internal interface on the router and
> cross
> > the MLPPP link it dies.
> >
> > I was just going to use CEF to handle the link with per-packet load
> sharing
> > with a dynamic routing protocol, but apparently the FlexWan
> controller
> > doesn't support it, or it barked about an unknown command.  Anyway
> trying to
> > debunk this I stripped it back to the above, just static routes
> between
> > A-to-B-to-C, and still it will not route. This is part of a larger
> network,
> > and none of the other remote enpoints will cross that multilink line,
> and I
> > can't pin down why.
> >
> > I am open to any suggestions, as I rarely use MLPPP, and am sure I am
> > missing something, but damn I would think two simple hops with static
> routes
> > should just go.   Thanks to any that can offer assistance on
> debunking this
> > one..
> >
> >
> > P.S. - Yes I know I have some routable, and some unroutable IP's, but
> this
> > is all behind a firewall, and gateways out, I just haven't gotten
> them to
> > pull the old public IP's out, granted that shouldn't matter for an
> internal
> > (in essence) isolated network.
> >
> >
> >
> > ---
> > Howard Leadmon
> >
> >
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