A wireless client PC running Windows XP does not see the Service Set Identifier SSID being broadcast by an Integrated Services Router (ISR) router. The SSID is configured in guest mode in the ISR router.
This issue is documented in Cisco bug ID CSCej57894.
ISR router does not broadcast SSID
Symptom: A wireless client PC running Windows XP does not "see" the SSID being broadcast by an ISR router. The SSID is configured as guest mode in the ISR router.
Condition: The problem is applied to Windows XP only. Windows 2000 does not experience the problem. The problem is introduced in 12.4(2)T.
Workaround: downgrade to 12.3(8)YI.
Some client 802.11b/g adapters are not able to view or scan SSID when broadcast, although they can associate with the SSID if the details are manually entered.
There are two types of scanning defined in dot11 standard: active scanning and passive scanning. Passive scanning is mandatory, while active scanning is optional, per standard.
Within active scanning, the client station can either send out a probe request with a desired SSID, or a NULL SSID (broadcast SSID), and the AP sends out a probe respond with matching SSID. In case of a broadcast SSID probe request, the Access Point (AP) sends out a probe response with guest SSID, if configured. This is all optional in dot11.
In this case, Microsoft uses active scanning (the broadcast active scanning) only to detect APs. The ISR routers originally did not support broadcast probe response, since it was not mandatory. Therefore, these clients are not able to see the guest SSID.
The problem occurs with Windows XP only. Windows 2000 does not experience the problem. The problem is introduced in version 12.4(2)T.
For a workaround, hard code the SSID into Win Zero Config supplicant clients, or others that did not see the SSID.
This is fixed in version 12.4(5.11)T, 12.4(2)T04, and 12.4(4)T02.