50
NetBIOS sessions occurs if the primary link fails and the redundant link is activated.
If this happens, end users need to log on and initiate another session.
IBM-Related Services in IBM-related services such as DLSw and APPN are affected by parameter settings in Token Ring the BRidge, SR, and LLC2 Services. Table 11 shows the required settings in source route (SR), source route transparent (SRT), and transparent bridging environments for each of the IBM-related services. When a NETBuilder bridge/router token-ring port is configured for both an IBM service such as DLSw and transparent bridging
or SRT bridging, connectivity problems and frame copy errors can occur. For this reason, 3Com recommends configuring token ring ports for source route only when possible.
In Table 11, DLSw refers to data link switching, and LNM refers to LAN Net Manager. The settings are shown in abbreviated form. 3Com-recommended configurations are shaded and shown in bold.
Table 11 IBM-Related Feature Settings for Token Ring Ports
| Port | Source Route | Transparen | | Route | | |
| Configurat | Bridging | t Bridging | Bridging | Discovery | LLC2 CONTrol | Frame Copy |
Services | ion | (-SR SRB) | (-BR TB) | (-BR CONT) | (-SR RD) | (-LLC2 CONT) | Errors |
| | | | | | | |
Bridging only | SR | SRB | NTB | B | NoLLC2 | Disable | None |
| | | | | | | |
Bridging only | SRT | SRB | TB | B | NoLLC2 | Disable | Low # Possible |
| | | | | | | |
Bridging only | T | NSRB | TB | B | NoLLC2 | Disable | Low # Possible |
| | | | | | | |
LNM | SR | SRB | NTB | B | LLC2 | Enable | None |
| | | | | | | |
DLSw | SR | SRB | NTB | NB B | LLC2 | Enable | None |
| | | | | | | |
DLSw | SRT | SRB | TB | NB* B* | LLC2 | Enable | High # Possible |
DLSw | T | NSRB | TB | NB* B* | NoLLC2 | Enable | High # Possible |
APPN | SR | SRB | NTB | NB B | LLC2 | Disable | None |
| | | | | | | |
APPN | SRT | SRB | TB | NB B | LLC2 | Disable | None |
| | | | | | | |
APPN | T | NSRB | TB | NB B | LLC2 | Disable | None |
| | | | | | | |
Default Setting | SRT | SRB | TB | NB | NoLLC2 | Disable | None |
*3Com recommends that you disable global bridging for this configuration. However, with global bridging disabled, the token-ring hardware does not filter unwanted transparent packets. The token-ring hardware copies each transparent packet for processing by the Enterprise OS software. This can generate many frame copy errors (see Token Ring Frame Copy Errors below for more information.) If you are seeing many Frame Copy Errors, consider setting global bridging on, which allows the hardware to learn and filter unwanted transparent packets. Since DLSw cannot block bridging loops, you must insure that none exist. As an alternative, you can prevent the bridge from forwarding by entering the following command: SETDefault -BRidge CONTrol = NoForward. The NoForward parameter allows the hardware to filter unwanted transparent packets, allows DLSw to send and receive LLC2 SNA and NetBIOS packets, but prevents these and other packets from bridging.
The row in Table 11 labeled DLSw with port configuration SR represents DLSw in a source-route-only port configuration. The entries in this row expand to the following Enterprise OS software configuration syntax:
SETDefault -BRidge CONTrol = Bridge NoBridge
SETDefault !<port> -SR SrcRouBridge = SrcRouBridge
SETDefault !<port> -BRidge TransparentBridge = NoTransparentBridge
SETDefault !<port> -SR RingNumber = <number> (1–4095) 0x<number> (1-FFF)
SETDefault !<port> -SR BridgeNumber = <number> (0-15) 0x<number> (0-F)
SETDefault !<port> -SR RouteDiscovery = LLC2
SETDefault !<port> -LLC2 CONTrol = Enable
