[j-nsp] PtP link over FR

Scott Morris swm at emanon.com
Thu Jul 17 10:21:25 EDT 2008


Fair enough.   I simply read the scenario involving two routers sharing a
frame-relay p2p link.  :)

Scott 

-----Original Message-----
From: Jesper Skriver [mailto:jesper at skriver.dk] 
Sent: Thursday, July 17, 2008 9:27 AM
To: Scott Morris
Cc: 'Farhan Jaffer'; 'Juniper Puck'; cisco-nsp at puck.nether.net
Subject: Re: [j-nsp] PtP link over FR

On Thu, Jul 17, 2008 at 07:49:09AM -0400, Scott Morris wrote:
> There is no ARP in frame-relay.  More specifically, on a P2P 
> subinterface, there's no mapping either.

I think you're mis understanding my suggestion, I was suggesting that router
A could only reach router B because the router in the middle did proxy ARP
for B's address, so A could reach it.

It has nothing to do with ARP over FR.

> The assumption is that if it's not MY address it must be yours.  So as 
> long as you believe the other side is within the defined subnet, then 
> you're good.
> 
> If you have 10.1.1.1/24 on one side, and 10.1.1.2/27 on the other, 
> they will still talk to each other just fine.  At least until you try 
> to run ospf or something that cares about the netmask!

Yes - unless you have 10.1.1.1/24 configured on A towards 'Juniper' and
10.1.1.2/27 configured on B towards 'Juniper'

/Jesper

> 
> Scott
> 
> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net
> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Jesper 
> Skriver
> Sent: Thursday, July 17, 2008 7:24 AM
> To: Farhan Jaffer
> Cc: Juniper Puck; cisco-nsp at puck.nether.net
> Subject: Re: [j-nsp] PtP link over FR
> 
> Let me guess, on Cisco Router A you got an ARP entry for Cisco Router 
> B's address when you put a Cisco router in the middle, as the Cisco 
> router has proxy-arp enabled by default.
> 
> Or to put it more clearly the IP addresses used FR p2p pvc is a subset 
> of the IP addresses used on the link between Cisco Router A and Juniper
Router.
> 
> Or on Cisco router A you have a static route without a next-hop 
> address to the IP subnet used on the FR link
> 
> In either case it's a mis configuration, that gets 'saved'/'hidden' by 
> the fact proxy-arp is enabled by default on the Cisco router.
> 
> /Jesper
> 
> On Thu, Jul 17, 2008 at 04:06:31PM +0500, Farhan Jaffer wrote:
> > Hi,
> > 
> > There is an interesting situation, let me discuss the scenario 
> > first,
> > 
> > Cisco Router A ----(same n/w) ---- Juniper Router -----(FR 
> > point-to-point pvc) ------- Cisco Router B.
> > 
> > PVC is Active & point to point connectivity is OK. But the ping 
> > response from cisco router A to B via FR is unreachable & vice versa.
> > 
> > however if i replace Juniper router with Cisco Router, it works fine.
> > 
> > Is there any IP forwarding like thing? or any other problem.
> > 
> > Thanks very much in advance.
> > 
> > -FJ
> > _______________________________________________
> > juniper-nsp mailing list juniper-nsp at puck.nether.net 
> > https://puck.nether.net/mailman/listinfo/juniper-nsp
> 
> /Jesper
> 
> --
> Jesper Skriver, jesper(at)skriver(dot)dk  -  CCIE #5456
> 
> One Unix to rule them all, One Resolver to find them, One IP to bring 
> them all and in the zone to bind them.
> _______________________________________________
> juniper-nsp mailing list juniper-nsp at puck.nether.net 
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> 
> _______________________________________________
> juniper-nsp mailing list juniper-nsp at puck.nether.net 
> https://puck.nether.net/mailman/listinfo/juniper-nsp

/Jesper

--
Jesper Skriver, jesper(at)skriver(dot)dk  -  CCIE #5456

One Unix to rule them all, One Resolver to find them, One IP to bring them
all and in the zone to bind them.



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