From: Justin Menga (Justin.Menga@xxxxxxxxxxxxxxxxxx)
Date: Tue Dec 12 2000 - 03:27:50 GMT-3
Hi,
I have figured out how to fix the problem below!!
Cisco documentation incorrectly lists the default Ethernet Type II OUI
encapsulation across Token Ring networks as being 90-compatible (OUI =
0000F8). It is in fact by default standard (OUI = 000000).
You can verify this by doing a show int to0:
....
....
Ethernet Transit OUI: 0x000000
Last input 00:00:00, output 00:00:03, output hang never
....
....
>From Cisco CD Documentation
(http://127.0.0.1:8080/cc/td/doc/product/software/ios120/12cgcr/ibm_r/brprt1
/brtb.htm#xtocid18335337):
The use of the standard OUI of 000000 in the encapsulation of Ethernet Type
II frames creates encapsulated frames on Token Rings that have formats
identical to SNAP-encapsulated frames. The router receiving such a frame on
a Token Ring for delivery on the Ethernet cannot distinguish between the
two, and therefore must make an arbitrary choice between presenting the
frame on the Ethernet as a SNAP-encapsulated frame or as an Ethernet Type II
frame. The choice has been made to present all such frames as Ethernet Type
II. Therefore, it is impossible to use the standard keyword if you wish to
bridge SNAP-encapsulated frames between Token Rings and Ethernets. Using
either the cisco or 90-compatible keywords does not present such a
restriction, because SNAP frames and Ethernet Type II-encapsulated frames
have different OUI codes on Token Ring networks.
Thus the fix for the problem is at each end where SR/TLB is taking place,
under your token ring interfaces:
int to0
ethernet-transit-oui {90-compatible | cisco}
ORIGINAL EMAIL:
Hi,
Just testing out IP/IPX/Appletalk with SR/TLB as follows:
R5-----ethernet-----R1------Ring 1-------R7------ethernet-----R2
In the above R1 and R7 have all routing (incl IP) disabled and are both
configured for SR/TLB. They also have 'multiring all' on each tokenring
interface to encapsulate IP/IPX/Apple with SRB RIFs.
IP works fine, no problems with connectivity.
IPX works fine, EXCEPT for using SNAP encapsulation - this does not work AT
ALL (no routing exchanges/pings).
Apple works semi-fine (using cable-range, encaps = SNAP), each router sees
the other router in 'show apple neighbor' and routing updates exchanged,
however you can't ping across the SR/TLB domain. When you try to ping,
'show apple arp' shows the entry for the neighbor is pending (i.e. ARP reply
not coming back). If you use appletalk address x.x (which changes encaps to
Ethernet II), appletalk works fine.
Any ideas on why SNAP has problems?
Regards,
Justin Menga MCSE+I CCNP CCSE ASE
WAN Specialist
Computerland New Zealand
PO Box 3631, Auckland
DDI: (+64) 9 360 4864 Mobile: (+64) 25 349 599
mailto: justin.menga@computerland.co.nz
Regards,
Justin Menga MCSE+I CCNP CCSE ASE
WAN Specialist
Computerland New Zealand
PO Box 3631, Auckland
DDI: (+64) 9 360 4864 Mobile: (+64) 25 349 599
mailto: justin.menga@computerland.co.nz
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