Cisco Systems Cisco MGX 8850 dspxbar

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Cisco MGX 8850 Routing Switch Command Reference

Release 2.0, Part Number 78-10467-04 Rev C0, October 2001

Chapter9 Troubleshooting Commands dspxbar

dspxbar

Display Crossbar—display the configuration of the crossbars

The dspxbar command displays general information about the configurat io n of a switch plane (or

switching fabric or crossbar , a lso synon y mous with swit ch ASIC) . The conf i gur ati on no rmall y ha s f ix ed

default values and is n o t c onfigurable.

Note The low-level dspxbar command normally applies to software or hardware development and

therefore is not useful fo r tr o ub le s ho o tin g at the network or node level. N or m a lly, to i s ol ate a

switching problem to determine whether to return a card, the dspswalm command is sufficient.

The crossbar-related commands are s p eci al de bug co mma nds with infrequent use. An eng in eer t ha t

needs to alter certain erro r thresholds for hardware o r sof tw ar e d evelopment can use the

cnfxbarerrthresh commands.

Before attempting to int er p re t t he contents of the dspxbar outpu t, s om e p er spe ctive on the crossbar

information is appropriate. The focus o f the cr o s sba r co mm ands is from the switch ASICs outwards, t o

the card slots. The reference poin t in re lat io n t o ca rd s lo ts is im portant and has to do with the wi ring of

the backplane. The connectivity be tw ee n the cards and the switch fabr ic —c ons istin g of all th e switch

ASICs in total—forms a mesh: each sw it ch ASI C co mm u nicat es with each card, and each card can use

any ASIC. Therefore, if one ASIC becomes inoperative, the switching fabric continues to support new

or existing connections within the switch, but the throughput falls far short of the maximum. Of less

drastic effect would be a condition w he re o ne b ack pl an e t r ace can n o lo n ge r carr y d at a b et w een a n

individual ASIC pin and a particular card slot. The dspxbarerrcnt command can help isolate such

faults. Regardless, at the node level, the dspswalms command is sufficient for determining whether to

replace the card with switchi ng p r oble m.

Refer to the examples to see th e lo ca ti on of each of the following fields. Th e g en er al in f orm a tio n th at

dspxbar displays is the:

•Selected ASIC number (default 0 is unspecified ).

•Number of the slot where the crossbar ASIC resides (7 or 8 for an MGX 8850 node).

•Number of the ASIC (0–2 in an MGX 8850 node).

•Revision number of the A S I C .

•Status of the ASIC.The status i s ei th er faile d or O K . I f th e status is failed, the other ASICs must

carry the switching load, and t h e t hr o ug hpu t o f th e switch falls below the maximum. In th is case,

Cisco Systems recommends you re pl ace th e card.

•The cell grant mode is always Mul ticas t Pr ef er re d.

•The Resync Sframe Tic is the rising edge of the clock. Sframe refers to a switch frame. (A switch

frame is a 60-byte cell that carrie s a 53-byte ATM cell plus a special header fo r i n ter n al fab ric use

between the switching fabric an d th e se rvice module.