From: Yakout Esmat (yesmat@xxxxxxxxxxxxxx)
Date: Tue Jul 16 2002 - 21:46:35 GMT-3
Thanks Brian and every one who participated in this topic. I think we are
all clear on this issue now.
-----Original Message-----
From: Brian Dennis [mailto:brian@5g.net]
Sent: Wednesday, July 17, 2002 1:41 AM
To: 'Yakout Esmat'; 'Groupstudy'
Subject: RE: Default route over ISDN
Yakout,
That's the whole point. It's a layer 3 to layer 2 mapping issue and not
technically a routing issue. Anytime you use an interface that is
essentially multipoint (physical Frame-Relay, physical ATM, BRI, etc)
you should never point the static route to the interface. It should be
pointed to the other sides IP address. Static routes pointed to an
interface in a WAN environment should normally be used only when the
interface type is "point-to-point" (i.e. only one possible destination
on the other side).
When you use the dialer string that is essentially what you are doing.
With a dialer string under a physical BRI interface the router can't
call different sites that maybe on the same IP subnet. In order to do
that you would need to use the dialer map statement and map the
different IP addresses to the different phone numbers. Technically you
can put more than one dialer string in but that is essentially there for
redundancy (i.e. the first number is busy so now try the second one).
Brian Dennis, CCIE #2210 (R&S/ISP Dial)
-----Original Message-----
From: Yakout Esmat [mailto:yesmat@iprimus.com.au]
Sent: Monday, July 15, 2002 11:12 PM
To: Brian Dennis; 'Ahmed Mamoor Amimi'; 'Groupstudy'
Subject: RE: Default route over ISDN
Brian,
It works because you have specific dialer map statement for the
10.1.1.1.
But if you remove it it will stop working. OR if you ping another
address it
will not work. Having default route should allow you to ping any
interface
on the other end (giving the other router can get back to you) not only
one.
I tried two different scenarios and both work fine:
First: use of dialer string
Second: the use of dialer profile
Yakout
-----Original Message-----
From: Brian Dennis [mailto:brian@5g.net]
Sent: Tuesday, July 16, 2002 11:40 AM
To: 'Ahmed Mamoor Amimi'; 'Yakout Esmat'; 'Groupstudy'
Subject: RE: Default route over ISDN
Mamoor,
Did you actually try this in a lab and verify that it didn't work? Works
in my lab. See below.
Brian Dennis, CCIE #2210 (R&S/ISP Dial)
<R2>
interface BRI0
ip address 192.168.1.2 255.255.255.0
dialer map ip 10.1.1.1 2029
dialer map ip 192.168.1.6 broadcast 2029
dialer-group 1
isdn switch-type basic-ni
isdn spid1 2028
!
ip route 0.0.0.0 0.0.0.0 BRI0
!
dialer-list 1 protocol ip permit
!
</R2>
<R6>
interface Loopback0
ip address 10.1.1.1 255.255.255.0
!
interface BRI0
ip address 192.168.1.6 255.255.255.0
dialer map ip 192.168.1.2 broadcast 2028
dialer-group 1
isdn switch-type basic-ni
isdn spid1 2029
!
dialer-list 1 protocol ip permit
</6>
R2#ping 10.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 36/36/40 ms
R2#
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Ahmed Mamoor Amimi
Sent: Monday, July 15, 2002 6:47 PM
To: Yakout Esmat; Brian Dennis; 'Groupstudy'
Subject: Re: Default route over ISDN
it will not work either that way by putting the map in local. u surely
need
to use the dialer profile or use dialer string if pointing to the bri
interface
-Mamoor
----- Original Message -----
From: Yakout Esmat <yesmat@iprimus.com.au>
To: Brian Dennis <brian@5g.net>; 'Groupstudy' <ccielab@groupstudy.com>
Sent: Tuesday, July 16, 2002 5:10 AM
Subject: RE: Default route over ISDN
> Brian,
>
> I see the logic behind it, and am sure that if I put another mapping
> statement in there it should work, I will try that and post the
results.
>
> Or maybe if I use dialer string instead of dialer map.
>
> CHeers
> yakout
>
> -----Original Message-----
> From: Brian Dennis [mailto:brian@5g.net]
> Sent: Tuesday, July 16, 2002 5:51 AM
> To: 'Yakout esmat'; 'Groupstudy'
> Subject: RE: Default route over ISDN
>
>
> Think about it like this. If you tell the router using the "ip route
> 0.0.0.0 0.0.0.0 bri0" command that all networks that aren't explicitly
> in the routing table are directly connected to BRI0, why would you
> expect the router to send them to 192.168.1.1?
>
> With the default route pointing to the interface the router wants to
> send the packet directly to address 10.1.1.1 (the packet's
destination).
> Since you don't have a dialer map to the 10.1.1.1 address you are
> getting the encapsulation failed messages. When you point the default
to
> the 192.168.1.1 address the router uses the 192.168.1.1 dialer map to
> get to it. As a side note you could also put a dialer map to the
> 10.1.1.1 address and you would have been able to ping it with the
> default route pointing to the BRI0 interface.
>
> What I recommend you doing is getting a "sniffer" and doing this on an
> Ethernet network. Try pointing a static route to an interface and try
> pointing a static route to an IP address of another router. You'll be
> able to see the difference in who the router ARPs for.
>
> Brian Dennis, CCIE #2210 (R&S/ISP Dial)
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Yakout esmat
> Sent: Monday, July 15, 2002 7:01 AM
> To: Groupstudy
> Subject: Default route over ISDN
>
> Any body aware of this problem..
>
> Scenario:
>
> 10.1.1.1/24--[R1]------(192.168.1.0/24)-----[R2]----
> ISDN
>
> 1) R2 is configured with a static default route
>
> Problem:
>
> 1) If the default static route on R2 is pointing to BRI0 interface "ip
> route
> 0.0.0.0 0.0.0.0 bri0", R2 can't ping 10.1.1.1 on R1. Getting
> "encapsulation
> failed" error when debuging ip packets, and R2 can't initiate a dial.
>
> 2) If I cahnge the default to point to next hop instead "ip route
> 0.0.0.0
> 0.0.0.0 192.168.1.1", every thing is sweet
>
> IOS 12.1, legacy ISDN with single dialer map statement is used, IP
> classless
> is on...
>
> I must be missing some thing.
>
> Thanks
>
> Yakout
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