IGX-URM may fail to pass traffic when operating on Bus B.
The IGX8400 supports 4 cell buses for passing data. Most of the cards in the IGX8400 use Cell Bus 1, exclusively, for passing data. Some cards, such as the IGX-URM, IGX-UXM and IGX-UXME use additional cell lane buses two, three and four. In addition to Cell Buses one through four, there is a fifth cell bus, Cell Bus R, used for redundancy when Cell Bus one fails. Cell Buses two through four are not protected by Cell Bus R.
Besides the cell buses, the IGX8400 also has control and clock buses named A and B.
In this irregularity, the Universal Router Module (URM) connections fail when using Bus B. The loss of the B Bus control and clocking causes data to fail to pass to cell buses.
This irregularity results in no traffic leaving the IGX-URM when using the B Bus on the IGX8400. In one instance, pings of 80 bytes or larger were failing.
If connections were added and operational when the IGX8400 was using the A Bus, no problem is detected and traffic from the URM to the rest of the IG8400 cards passes normally. If the IGX8400 subsequently switches to the B Bus, the URM traffic will cease to pass, resulting in loss of connectivity to remote resources, ping failures and session drop outs which cannot be re-established. The loss of connectivity is a silent failure; no alarms or traps are generated.
If connections are added to the IGX-URM while the IGX8400 is using the B Bus, the connections will add normally and appear in the dspcons screens with no failure indication. However, the connections will not pass traffic.
Workaround: If possible, use Bus A. Use the dspbuses command to see if the A bus or B bus is active. If the B Bus is active, issue the cnfbus t command to toggle to the A bus. This workaround is effective until the defective IGX-URM can be replaced.
Solution: Verify that the affected card's serial number listed in this field notice. Request a return materials authorization (RMA) coded "ARFN" (Administrative Request - Field Notice) to replace the IGX-URM.
Verification: Not all the IGX-URMs listed in the serial number section will fail using Bus B.
For More Information
If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:
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