System information

Troubleshooting IBM 10-229
Translational Bridging: Client Cannot Connect to Server
Ethernet–to–Token
Ring address mapping
is misconfigured
Step 3 Use the show rif exec command to determine whether the target Token
Ring station is visible on the internetwork.
When configured for translational bridging, the router extracts the RIF of
a packet received from the Token Ring network and saves it in a table.
The router then transmits the packet on the Ethernet network. Later, the
router reinserts the RIF when it receives a packet destined for the
originating node on the Token Ring side.
Example:
The following is sample output from the show rif command:
Router# show rif
Codes: * interface, - static, + remote
Hardware Addr How Idle (min) Routing Information
Field
5C02.0001.4322 rg5 - 0630.0053.00B0
5A00.0000.2333 TR0 3 08B0.0101.2201.0FF0
5B01.0000.4444 - - -
0000.1403.4800 TR1 0 -
0000.2805.4C00 TR0 * -
0000.2807.4C00 TR1 * -
0000.28A8.4800 TR0 0 -
0077.2201.0001 rg5 10 0830.0052.2201.0FF0
Step 4
If Ethernet and Token Ring end systems are visible, statically configure
any relevant server MAC addresses in the client configurations so that
clients can listen to the server advertisements directly.
One case in which static mapping is required is when bridging DEC LAT
traffic over a translational bridge. LAT services on Ethernet are
advertised on a multicast address that is mapped by some translational
bridges to a broadcast address on the Token Ring side. Routers do not
support this mapping.
Vendor code
mismatch
Older Token Ring implementations require that the vendor code (OUI
1
field) of
the SNAP
2
header be 000000. Cisco routers modify this field to be 0000F8 to
specify that the frame was translated from Ethernet Version 2 to Token Ring. This
can cause problems on older Token Ring networks.
Specify the ethernet-transit-oui interface configuration command to force the
router to make the vendor code field 000000. This change is frequently required
when there are IBM 8209s (IBM Token Ring-to-Ethernet translating bridges) in
the network.
The following is an example of the ethernet-transit-oui command:
ethernet-transit-oui [90-compatible | standard | cisco]
Syntax Description:
• 90-compatible—OUI used 0000F8 by default, when talking to other Cisco
routers. Provides the most flexibility.
• standard—OUI used 000000 when talking to IBM 8209 bridges and other
vendor equipment. Does not provide for as much flexibility as the other two
choices.
• cisco—OUI used 00000C, provided for compatibility with future equipment.
Example:
The following example specifies Cisco’s OUI form:
interface tokenring 0
ethernet-transit-oui cisco
Possible Problem Solution