QLLC dlsw question

[a.mountouris]

Hello Forum,

this is actually a design issue and I just want a second opinion on this. We have about 40 branches that connect to the Mainframe through 3745(FEP) by ODLC (x25) lines. There are no SNI links, only subarea.

We are thinking of getting rid of 3745 and use cisco routers and OSA cards instead. So, we are thinking of having 2x7206 routers, with dlsw software and 2 OSA fast ethernet express. Then the remote connections will be x.25 to the routers, and dlsw will translate QLLC to LLC frames towards the OSAs. So, we need to implement LOCAL DLSw+ on cisco plus x.25 (QLLC) to LLC translation.

Another though is to have also SNASw on the cisco and use HPR/IP to the OSA cards. Will this work with the QLLC to LLC (through the local dlsw) translation?

Any other suggestions?

Regards, Apostolos.

[mbinzer]

Hi,

dlsw local switching can do the conversion from qllc to llc. You can then have your OSA cards connected via ethernet.

Dlsw local switching can also do the conversion between qllc and snasw. You would again configure a snasw vdlc port.

In case of dlsw local switch to llc2 on to a ethernet lan you use a physical dlc, ethernet lan.

In case of connecting to snasw you use a virtual dlc, vdlc.

thanks...

Matthias

[a.mountouris]

Hello Matthias,

so, if I have the resource at x.25 cloud and the mainframe at the ethernet (the opposite as the example of qllc to ethernet presented in cisco site), then what would be configured at the remote server as destination address? He still have the x25 definitions, so would I configure as destination address the x25 address of the router that will do the media conversion?

On this router, can I code the same x25 alias to more than one interfaces?

[mbinzer]

Hi,

yes, as far as my understanding goes the destination address of the x25 client will be the x121 address of the router in that case. If the same client needs to reach multiple pu's you need to configure x121 subaddresses at the router and then have the client dial the x121 address + the appropriate subaddress.

In respect to the x25 alias. The way i understand this command it is associated with a specific x121 address and the interface this address is configured on. You can have multiple alias commands in case you have multiple serial interfaces with different x25 addresses.

thanks...

Matthias

[a.mountouris]

Another issue I want to address is this. Let say I configure a x.121 address to an interface. If a call comes with this one as destination, then the call is accepted and local processing can occur (like protocol mapping). Does this local processing include also media conversion? If a call comes with destination address diferent than the one defined on the interface, then the router just switches this call according to the x25 routing? Or discards this call?