ASN AS21508 is an Autonomous System Number used to identify a network for BGP internet routing.

Who manages ASN AS21508?

AS21508 is listed under Comcast Cable Communications, LLC.

What do peers, upstreams, and downstreams mean in ASN data?

Peers are lateral network interconnections, upstreams are transit providers, and downstreams are customer networks receiving connectivity.

What are routes and IP ranges for an ASN?

Routes and IP ranges are the network prefixes announced by the ASN on the internet and show the address space it originates.

Why is WHOIS data shown for an ASN?

WHOIS data provides registration and contact context for ASN ownership, administration, and operational reference.

How can I access the full ASN tables?

The page shows a preview of large ASN datasets. Use the page controls to load more rows, and upgrade to a paid plan for complete access.

AS21508 Comcast Cable Communications, LLC

ASN Lookup Tool

Comcast Cable Communications, LLC comcast.com

US 84 Routes

AS Data

AS21508

AS21508 – Comcast Cable Communications, LLC

AS Number	21508
AS Name	COMCAST-21508
Organization	Comcast Cable Communications, LLC(cccs)
Country	US
Website	comcast.com
Number of IPv4 Routes	18
Number of IPv6 Routes	66
ASN type	ISP
Registry	ARIN
Date Allocated	2001-05-16

ASN Intelligence API for production workflows

Use ASN data for AS21508 in automation: routing intelligence, peering analysis, ownership checks, and network observability.

Access complete peers, upstreams, downstreams, routes, WHOIS, and contact intelligence via our API. Learn more

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IP Ranges

Route	Origin	Origin Name	ISP	# IPs
2001:559:3b9::/48	AS21508	Comcast Cable Communications, LLC	Comcast Cable Communications, LLC	~1×10²⁴
2001:559:c10a::/48	AS21508	Comcast Cable Communications, LLC	Comcast Cable Communications, LLC	~1×10²⁴
204.194.47.0/24	AS21508	Comcast Cable Communications, LLC	Va. Dept. of Rehabilitative Services	256
2001:559:c4db::/48	AS21508	Comcast Cable Communications, LLC	Comcast Cable Communications, LLC	~1×10²⁴
2001:559:7db::/48	AS21508	Comcast Cable Communications, LLC	Comcast Cable Communications, LLC	~1×10²⁴
2001:559:7a7::/48	AS21508	Comcast Cable Communications, LLC	Comcast Cable Communications, LLC	~1×10²⁴
2001:559:c1ca::/48	AS21508	Comcast Cable Communications, LLC	Comcast Cable Communications, LLC	~1×10²⁴
2001:559:804c::/48	AS21508	Comcast Cable Communications, LLC	Comcast Cable Communications, LLC	~1×10²⁴
2001:559:8445::/48	AS21508	Comcast Cable Communications, LLC	Comcast Cable Communications, LLC	~1×10²⁴
2001:559:5c9::/48	AS21508	Comcast Cable Communications, LLC	Comcast Cable Communications, LLC	~1×10²⁴

Raw Whois Response

#
# ARIN WHOIS data and services are subject to the Terms of Use
# available at: https://www.arin.net/resources/registry/whois/tou/
#
# If you see inaccuracies in the results, please report at
# https://www.arin.net/resources/registry/whois/inaccuracy_reporting/
#
# Copyright 1997-2026, American Registry for Internet Numbers, Ltd.
#


ASNumber:       21508
ASName:         COMCAST-21508
ASHandle:       AS21508
RegDate:        2001-05-16
Updated:        2021-01-25    
Ref:            https://rdap.arin.net/registry/autnum/21508



OrgName:        Comcast Cable Communications, LLC
OrgId:          CCCS
Address:        1800 Bishops Gate Blvd
City:           Mt Laurel
StateProv:      NJ
PostalCode:     08054
Country:        US
RegDate:        2001-09-18
Updated:        2020-11-18
Ref:            https://rdap.arin.net/registry/entity/CCCS


OrgAbuseHandle: NAPO-ARIN
OrgAbuseName:   Network Abuse and Policy Observance
OrgAbusePhone:  +1-888-565-4329 
OrgAbuseEmail:  abuse@comcast.net
OrgAbuseRef:    https://rdap.arin.net/registry/entity/NAPO-ARIN

OrgTechHandle: IC161-ARIN
OrgTechName:   Comcast Cable Communications Inc
OrgTechPhone:  +1-856-792-2300 
OrgTechEmail:  CNIPEO-Ip-registration@cable.comcast.com
OrgTechRef:    https://rdap.arin.net/registry/entity/IC161-ARIN

OrgRoutingHandle: ROUTI25-ARIN
OrgRoutingName:   Routing
OrgRoutingPhone:  +1-856-792-2300 
OrgRoutingEmail:  routing@comcast.com
OrgRoutingRef:    https://rdap.arin.net/registry/entity/ROUTI25-ARIN


#
# ARIN WHOIS data and services are subject to the Terms of Use
# available at: https://www.arin.net/resources/registry/whois/tou/
#
# If you see inaccuracies in the results, please report at
# https://www.arin.net/resources/registry/whois/inaccuracy_reporting/
#
# Copyright 1997-2026, American Registry for Internet Numbers, Ltd.
#

Parsed Whois Response

Peers

AS Number	Description	Country
AS14583	Virginia Information Technologies Agency VITA	US
AS394276	TurnAround Factor, Inc.	US
AS393591	Gamewood Technology Group, Inc.	US
AS395441	EdgeConneX, INC	US
AS393415	LITTLER MENDELSON, P.C.	US
AS397190	WSP	US
AS400114	Apogee Telecom Inc.	US
AS23209	Virginia Housing Development Authority	US
AS399232	Seton Home Study School	US
AS36364	Mary Washington Hospital, Inc.	US

Upstreams

AS Number	Description	Country
AS7922	Comcast Cable Communications, LLC	US

Downstreams

AS Number	Description	Country
AS36244	Shenandoah Valley Electric Cooperative	US
AS14583	Virginia Information Technologies Agency VITA	US
AS18773	County of Henrico	US
AS394276	TurnAround Factor, Inc.	US
AS2134	GS Virtual Network Produban	ES
AS40641	MGW Telephone Company, Inc.	US
AS19923	Shenandoah University	US
AS393591	Gamewood Technology Group, Inc.	US
AS395772	Augusta Health Care, Inc	US
AS395441	EdgeConneX, INC	US