In OSPF, two multicast addresses are used. When an OSPF area is started, one router is elected the Designated Router (DR), and another is made the Backup Designated Router (BDR).

224.0.0.5 is used by all OSPF routers (hello packets)
224.0.0.6 is used by (B)DR to exchange link state information

Vulnerability Announcements

Multiple Vulnerabilities in Cisco Unified IP Phones 7900 Series

Default Credentials Vulnerability in Cisco Network Registrar

Cisco RVS4000 and WRVS4400N Web Management Interface Vulnerabilities

Cisco Content Services Gateway Denial of Service Vulnerability

Multiple Vulnerabilities in Cisco AnyConnect Secure Mobility Client

Cisco SA 500 Series Security Appliances Web Management Interface Vulnerabilities

Cisco ASR 9000 Series Routers Line Card IP Version 4 Denial of Service Vulnerability

Field Notices

(Cisco CRS Series Routers) Field Notice: FN - 63126 - CRS: 1OC768-ITU/C cards may experience High Bit Error Rate (BER) or loss of Transmit power incidents in certain batch of optical module - Workaround Fix on Failure

(Cisco CRS Series Routers) Field Notice: FN - 63046 - CRS - 1OC768-POS-SR cards May Experience Bit Error Rate (BER) Incidents Due to Onboard Short - Fix on Failure

(Cisco MGX 8800 Series Switches) Field Notice: FN - 63319 - MGX - VXSM-SW May Report Error Code 400 for CAS Signaling Call - Workaround Available

(Cisco 7800 Series Media Convergence Servers) Field Notice: FN - 63324 - A Limited Number of HP DL380-G6 Servers Shipped Prior to November 16, 2009 May Unexpectedly Reboot

(Cisco 800 Series Routers) Field Notice: FN - 63343 - PCEX-3G-HSPA-R6 Modem not Recognized in Cisco IOS 15.1(1)T of Cisco 880G Series Router - Cisco IOS Upgrade Required

(Cisco MDS 9500 Series Multilayer Directors) Field Notice: FN - 63132 - MDS9000 - Potential DIMM Memory Issue in a Small Number of DS-X9530-SF2-K9 Supervisor Cards Manufactured Between September 2007 and February 2008