Cisco Systems DOC-7814982 GBIC and SFP Module Security and Identification

28-13
Catalyst 2950 Desktop Switch Software Configuration Guide
78-14982-01
Chapter 28 Troubleshooting GBIC and SFP Module Security and Identification
GBIC and SFP Module Security and Identification
Cisco-app roved Gigabit Inter face Converter (GBI C) modules have a serial EE PROM that co ntains the
module seri al numbe r, the vendor name and ID, a uniqu e sec uri ty c od e, a nd cyclic redu nda ncy chec k
(CRC). When a GBIC module is inser ted in the switch , the switc h softw are re ads the EEPROM to che ck
the ser ial numb er, vendor nam e and vendor ID, an d r ecom pute the sec uri ty c ode and C RC. If the se r ial
number, the vendor na me o r vend or ID, the s ecur ity c ode, or CRC is invalid, the s wit ch p lac es th e
interface in an error- disabled state.
Note If you ar e usin g a non -Cis co ap proved GBI C modu l e, rem ove the GBIC fr om the swit ch, a nd re pla ce it
with a Cisc o-ap proved mo dule .
After inserting a Cisco-approve d GBIC or SFP module, use the errdisable r eco very ca use gbic-invalid
global configuration command to verify the port status, and enter a time interval for recovering from the
error-disabled state. After the elapsed interval, the switch brings the interface out of the error-disabled
state and retries the operation. For more information about the errdisable recovery comma nd, refe r to
the comm and refe rence fo r this release.
High Re ed-So l omon
error coun t w ithout
CRC error s
•Interleaver is helping Reed-Solomon error correction to function correctly in a noisy
environment. This situation means that the system is on the verge of generating CRC errors.
– Change to a profile that has the in terleaver feature enabled, such as the LRE-5, LRE-10,
LRE-1 5, LR E-10-1, LR E-10- 3, or LRE- 10-5 pro file.
– Change to a profile with a lower data rate (for example, use LRE-5 instead of LRE-15) to
increase the noise margin .
•The LRE link length and quality are close to the limit of operation.
– Change to a profile with a lower data rate (for example, use LRE-5 instead of LRE-15).
– Reduce the effect of stubs or bridge taps by terminating them with 300-ohm microfilters.
Ethernet performance
degradation due to
excessive network
latency
Interleaver introduces extra latency to increase noise margin.
•Adjust up per-layer ne twor k p roto cols t o al low for hi gh la tency.
•Change to a prof ile with a higher da ta ra te to incr ea se link ba ndwid th . This de creases the noise
margin.
•Sele ct a low-lat ency (LL) LR E pro file, such as LRE -5LL , LRE- 10LL, or LRE-15 LL.
Note Use the LL private profiles with care. The LL profiles have the LL feature enabled and the
interleaver feature turned off. The LL feature does not delay data transmission, but it makes
data more susceptible to interruptions on the LRE link.
All o t her p rofiles , p ubli c a nd private, have the in terle aver feat ur e e na bled a nd t he L L
feat ure disa bled. Th e inter leaver feature provides maxi mum pro tectio n against small
interruptions on the LRE link but delays data transmission. For more information about the
LRE profiles, see the “Types of LRE Profiles” section on page 7-17.
LRE link quality
reduced in installations
with bundle d cable s
Cross-talk between the LRE links is causing all links to degrade. Disable unused LRE ports by using
the lre shutdown interface configurati on comma nd.
Table 28-4 LRE Port Problems (continued)
Probl e m Suspected Cau s e and Suggested So l uti o n