Vista - what is ip 224.0.0.252 used by host process for?

Do I need to allow this?
File Version: 6.0.6001.18000
File Description: Host Process for Windows Services (svchost.exe)
File Path: C:\Windows\System32\svchost.exe
Digital Signature:
Process ID: 0x550 (Hexadecimal) 1360 (Decimal)

Connection origin: local initiated
Protocol: UDP
Local Address: 192.166.123.2
Local Port: 49428
Remote Name:
Remote Address: 224.0.0.252
Remote Port: 5355

Ethernet packet details:
Ethernet II (Packet Length: 66)
Destination: 01-00-5e-00-00-fc
Source: 00-22-15-f1-1a-92
Type: IP (0x0800)
Internet Protocol
Version: 4
Header Length: 20 bytes
Flags:
.0.. = Don't fragment: Not set
..0. = More fragments: Not set
Fragment offset:0
Time to live: 1
Protocol: 0x11 (UDP - User Datagram Protocol)
Header checksum: 0x9622 (Correct)
Source: 192.166.123.2
Destination: 224.0.0.252
User Datagram Protocol
Source port: 5313
Destination port: 37088020
Length: 8
Checksum: 0x2f97 (Incorrect - Checksum should be 0x5625)
Data (32 Bytes)

....

224.0.0.252
Record Type: IP Address


OrgName: Internet Assigned Numbers Authority
OrgID: IANA
Address: 4676 Admiralty Way, Suite 330
City: Marina del Rey
StateProv: CA
PostalCode: 90292-6695
Country: US

NetRange: 224.0.0.0 - 239.255.255.255
CIDR: 224.0.0.0/4
NetName: MCAST-NET
NetHandle: NET-224-0-0-0-1
Parent:
NetType: IANA Special Use
NameServer: FLAG.EP.NET
NameServer: STRUL.STUPI.SE
NameServer: NS.ISI.EDU
NameServer: NIC.NEAR.NET
Comment: This block is reserved for special purposes.
Comment: Please see RFC 3171 for additional information.
Comment:
RegDate: 1991-05-22
Updated: 2002-09-16

OrgAbuseHandle: IANA-IP-ARIN
OrgAbuseName: Internet Corporation for Assigned Names and Number
OrgAbusePhone: +1-310-301-5820
OrgAbuseEmail: abuse@xxxxxx

OrgTechHandle: IANA-IP-ARIN
OrgTechName: Internet Corporation for Assigned Names and Number
OrgTechPhone: +1-310-301-5820
OrgTechEmail: abuse@xxxxxx


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