From: ccie2be (ccie2be@nyc.rr.com)
Date: Fri Aug 15 2003 - 11:53:54 GMT-3
Hi Jason,
I was also very confused about this same scenario just this week but some
people here helped me out. Here's how I understand it.
Set up dlsw using the loopback interfaces in both the local peer and remote
peer statements and tcp encap. Then configure your routing so that if the
serial link which is your primary link goes down, the routing protocol will
re-establish a connection via the isdn link.
Since dlsw doesn't care which link it uses, it will use any link available
as long as a path to the remote peer's loopback is in the route table.
Regarding the dlsw optional parameters: keepalive, timeout, dynamic, and
backup peer.
You definately don't use the backup peer option because dlsw requires that
the back up has to a different peer than the primary peer. Also, typically,
the idea with dlsw is to get to an IBM mainframe and so the primary dlsw
peer and the backup dlsw peer are both attached to the mainframe via a
common token ring segment. This provides 2 paths to the mainframe - 1 via
the primary and 1 via the backup dlsw peers.
The other 3 parameters have to do with when dlsw establishes and brings down
a connection to the remote peer. Remember that as long as dlsw has a path
to the remote peer, it can establish a connection but that doesn't mean that
you want dlsw to trigger isdn to make a call since your routing
configuration takes care of that so you don't need to define dlsw traffic as
interesting. The dynamic option causes dlsw to wait until it has dlsw
traffic before establishing a peer connection and this option will work over
a serial link or a dialup link. The keepalive and timeout options specify
when dlsw will terminate a connection.
The decision you have to decide is whether you want dlsw to make a peer
connection whether or not there's dlsw traffic and if you want dlsw
keepalives to flow over the isdn link.
I haven't yet tried to lab what happens when dlsw is defined as interesting
traffic and the priamry link is up. I don't know if dlsw will trigger a
isdn call or just use the serial link.
Hope this helped out. dt
----- Original Message -----
From: "Jason Cash" <cash2001@swbell.net>
To: <ccielab@groupstudy.com>
Sent: Thursday, August 14, 2003 10:53 PM
Subject: DLSW - ISDN
> All the examples that I have searched thru in the archives don't
illustrate
> the scenario I am trying to understand. Given the following, what would
be
> the best implementation:
>
> R2 (2.2.2.2) R5(5.5.5.5)
> B0-----------B0
> S0-----------S0
>
> The DLSW traffic, typically would go over the s0 links, and I understand
how
> to set that up. But if you config this scenario without taking the isdn
> into account and the isdn then kicks in, then what. On the flip side, if
> you config with the ISDN in mind, then (wouldn't when the serial
connection
> is active) it would have the keepalive applied to it? So I am confused as
> to setting this scenario up. Ihave serached thru the archive and have
only
> gotten more confused. Furthermore, the link an archive post doesn't even
> use the 'keepalive 0' or 'timeout commands:
>
> http://www.cisco.com/warp/customer/697/dlsw_backup_peer.html
>
> From that example, I am not sure how it is working. I was under the
> impression, from the solie book, that the 'keepalive' and 'timeouts' were
> needed.
>
>
> _______________________________________________________________________
> You are subscribed to the GroupStudy.com CCIE R&S Discussion Group.
>
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Tue Sep 02 2003 - 18:53:59 GMT-3