DLSw circuit question

[a.mountouris]

Hello forum,

there is a strange behaviour of a dlsw connection that I wish to discuss here.

We had (long time ago) established a dlsw connection between two mainfrmes, one had an OSA T/R adapter and the other a 3745 in front. This circuit was up and running and soon we "forgot" about it. No problems were ever reported.

Some months ago, we changed the T/R OSA to Ethernet OSA. Again, doing all necessary changes, the sessions were established ok. But we notice a strange behaviour. Every morning, the PU is in a strange state, either pending or conct and we have to vary inact/act the PU so that the sessions can be established. After about 1 to 2 minutes everyhing is ok.

We do not have taken any traces or displays, but I wanted to ask, is it something to do with the dlsw circuit between the two MAC addresses (ETH OSA and 3745) dropping through the night?

Is there any time limit that an established circuit is active?

Can we change this time?

During night, of course there is no activity between the two mainframes, so we guess a timer expires and the PU needs reactivation.

HAPPY NEW YEAR!!!!

[mbinzer]

Hi,

there is no time limit to the life of a dlsw circuit in cisco ios.

As long as both ends are "in session" the circuit will stay up indefnetly. There is also no need for any circuit activity ect.

If the circuit goes down it needs to be investigated who is shutting it down.

Depending on the ios version you are running you can do a show dlsw circuit history detail. This will give you a first idea which end is disconnecting.

I would also advice to open a tac case to have the issue properly worked on and documented.

thanks...

Matthias

[ehirsel]

What devices are in between the 3745 and the OSA? Does the 3745 have a Token-Ring or an ethernet lan connection?

[a.mountouris]

Hello,

sorry for the inconvninece this post caused. The problem atcually was on the switch that this connection was on, on the side of the OSA card. The switch for an unknown reason inactivated the interface and many messages of multiple collisions were displayed on the console. We moved the connection to another switch an now everything is working fine. By the way, 3745 has token ring and is sdlc attached to the the manframe.

[ehirsel]

Glad to hear your problem was fixed. You may want to see if the enet OSA can have full-duplex configured as well as an explicit speed, and if the switch it connects to can allow for matching speed and duplex values. I wonder if the original issue was due to auto-negotiation.

[kam.sin.ho]

I am trying to connect the following config:

IBM Host A <-OSA-> Ethernet <--> router <-- Serial --> IP Cloud (FR / ??) <--> FEP (with FR support) <--> IBM Host B.

IBM Host A runs CICS App, Terminals connected to the FEP on the IBM Host B side logon to CICS App on IBM Host A.

The person before me designed the connection using FRAS. After a few weeks of trying, I found out it won't work.

Based on the scanning throught this forum it seems that I can do this by using dlsw such as:

IBM Host A <-OSA-> Ethernet <--> router (DLsw) <-- Serial --> IP Cloud (FR / ??) <--> router (DLsw) <--> FEP (with FR support) <--> IBM Host B.

Since I am new to the network, I need a bit more help on the config on the IBM HOST A (VTAM XCA), both dlsw routers and the FEP on IBM Host B.

Also at the moment the link is Frame-relay (direct). Can the IBM Host A with OSA card and the 2 dlsw routers able to utilise the same frame-relay link or we have to get another type of wan link?