System information

Troubleshooting IBM
Book Title
10-230
SRT Bridging: Client Cannot Connect to Server
Symptom: Clients cannot communicate over a router configured to perform SRT bridging. Packets
are not forwarded by the SRT bridge.
Note SRT bridging allows you to implement transparent bridging in Token Ring environments. It
is not a means of translating between SRB on a Token Ring and transparent bridging on Ethernet (or
other) media.
Table 10-8 outlines the problems that might cause this symptom and describes solutions to those
problems.
Table 10-8 SRT Bridging: Client Cannot Connect to Server
Cisco and non-Cisco
translational bridges
in parallel
Step 1 Check for translational bridges in parallel with the Cisco translational
bridge. If there are any parallel non-Cisco translational bridges, loops
will probably be created.
Step 2 Because implementing translational bridging defeats the spanning-tree
mechanism of both transparent bridging and SRB environments, you
must eliminate all loops caused by inserting the translational bridge. A
transparent spanning tree and a source-bridge spanning tree cannot
communicate with one another.
Trying to bridge protocols
that embed MAC
addresses in the
Information field of the
MAC frame (such as
IP ARP
3
, Novell IPX,
or AARP
4
)
If MAC addresses are embedded in the Information field of the MAC frame,
bridges will be unable to read the address. Bridges will therefore be unable to
forward the traffic.
Step 1 If you are attempting to bridge this type of protocol, route the protocol
instead.
Step 2 If you still cannot communicate over the router, contact your technical
support representative.
1 OUI = organizational unique identifier
2 SNAP = Subnetwork Access Protocol
3 ARP = Address Resolution Protocol
4 AARP = AppleTalk Address Resolution Protocol
Possible Problem Solution
Trying to bridge frames containing
RIF from Token Ring network to
Ethernet network over an SRT bridge
Use translational bridging instead of SRT bridging to allow
SRB-to-transparent bridging translation.
Because SRT bridging works only between Ethernet and Token Ring, any
packet containing a RIF is dropped when SRT bridging is used.
Attempting to transfer large frame
sizes
Problems will occur if Token Ring devices transmit frames exceeding the
Ethernet MTU
1
of 1500 bytes. Configure hosts on the Token Ring to
generate frame sizes less than or equal to the Ethernet MTU.
Possible Problem Solution