Report for 21508

Name

COMCAST-21508 - Comcast Cable Communications, LLC, US

AS Adjacency Report

In the context of this report "Upstream" indicates that there is an adjacent AS that lines between the BGP table collection point (in this case at AS2.0) and the specified AS. Similarly, "Downstream" refers to an adjacent AS that lies beyond the specified AS. This upstream / downstream categorisation is strictly a description relative topology, and should not be confused with provider / customer / peer inter-AS relationships.

21508 COMCAST-21508 - Comcast Cable Communications, LLC, US

  Adjacency:    26  Upstream:     1  Downstream:    25
  Upstream Adjacent AS list
    AS7922          COMCAST-7922 - Comcast Cable Communications, LLC, US
  Downstream Adjacent AS list
    AS11739         CHIRISA-TECHNOLOGY-PARKS-01 - Digital Fortress, Inc., US
    AS14583         VITA-VSP-1 - Virginia Information Technologies Agency (VITA), US
    AS13335         CLOUDFLARENET - Cloudflare, Inc., US
    AS19923         SHENANDOAH-UNIV - Shenandoah University, US
    AS32540         HP-HOOD - HP Hood, US
    AS2134          GSVNET-AS - Santander Global Technology and Operations, S.L., ES
    AS18773         HENRICO-AS - County of Henrico, US
    AS15297         EPLUS-ASN - EPLUS, Inc., US
    AS15173         NEWMA-11 - Newmarket Corporation, US
    AS36364         MHSNET - Mary Washington Hospital, Inc., US
    AS36244         SVEC - Shenandoah Valley Electric Cooperative, US
    AS395772        AHC-AS - Augusta Health Care, Inc, US
    AS396083        ARVUS-160-84 - Framatome Inc., US
    AS399099        PCPS-ASN - petersburg city public schools, US
    AS399607        LCPS-VA - Louisa County Public Schools, US
    AS399938        BHE-TRANSIT - Berkshire Hathaway Energy Company, US
    AS397039        WORLDSTRIDES - WorldStrides, US
    AS400114        APOG-RBC - Apogee Telecom Inc., US
    AS54391         CRUTCHFIELD - Crutchfield New Media LLC, US
    AS54219         SCHAWK-INC - Matthews International Corporation, US
    AS40641         MGWTEL - MGW Telephone Company, Inc., US
    AS62971         COUNTY-OF-CHESTERFIELD-VA - County of Chesterfield, US
    AS63468         INFINITTNA - Infinitt North America, Inc., US
    AS54883         CORVA - City of Richmond, Virginia, US
    AS36040         YOUTUBE - Google LLC, US

Announced Prefixes

Rank  AS       Type    Originate Addr Space  (pfx)   Transit Addr space  (pfx)  Description
2966  AS21508        ORG+TRN Originate:      71424 /15.88  Transit:      80128 /15.71 COMCAST-21508 - Comcast Cable Communications, LLC, US

Aggregation Suggestions

        Filter: Aggregates, Specifics

This report does not take into account conditions local to each origin AS in terms of policy or traffic engineering requirements, so this is an approximate guideline as to aggregation possibilities.

 Rank AS            AS Name                                      Current  Wthdw  Aggte  Annce Redctn       %
35568 AS21508       COMCAST-21508 - Comcast Cable Communications,     18      0      0     18      0   0.00%


  Prefix               AS Path                              Aggregation Suggestion
  50.204.101.0/24      4777 2516 7922 21508   
  50.205.217.0/24      4777 2516 7922 21508   
  50.216.229.0/24      4777 2516 7922 21508   
  50.217.1.0/24        4777 2516 7922 21508   
  50.217.207.0/24      4777 2516 7922 21508   
  50.218.47.0/24       4777 2516 7922 21508   
  50.219.12.0/22       4777 2516 7922 21508   
  50.228.113.0/24      4777 2516 7922 21508   
  50.229.113.0/24      4777 2516 7922 21508   
  50.229.114.0/24      4777 2516 7922 21508   
  50.235.34.0/24       4777 2516 7922 21508   
  141.104.0.0/16       4777 2516 7922 21508   
  157.240.147.0/24     4777 2516 7922 21508   
  157.240.148.0/24     4777 2516 7922 21508   
  173.242.174.0/24     4777 2516 7922 21508   
  198.90.112.0/22      4777 2516 7922 21508   
  204.194.47.0/24      4777 2516 7922 21508   
  205.223.19.0/24      4777 2516 7922 21508   

Advertisements that are fragments of the original RIR allocation (more specifics) originated by this AS.

AS21508   17 More Specifics   18 Total Advertisements   COMCAST-21508 - Comcast Cable Communications, LLC, US
    50.204.101.0/24               50.128.0.0/9
    50.205.217.0/24               50.128.0.0/9
    50.216.229.0/24               50.128.0.0/9
    50.217.1.0/24                 50.128.0.0/9
    50.217.207.0/24               50.128.0.0/9
    50.218.47.0/24                50.128.0.0/9
    50.219.12.0/22                50.128.0.0/9
    50.228.113.0/24               50.128.0.0/9
    50.229.113.0/24               50.128.0.0/9
    50.229.114.0/24               50.128.0.0/9
    50.235.34.0/24                50.128.0.0/9
    157.240.147.0/24              157.240.0.0/16
    157.240.148.0/24              157.240.0.0/16
    173.242.174.0/24              173.242.160.0/20
    198.90.112.0/22               198.90.96.0/19
    204.194.47.0/24               204.194.40.0/21
    205.223.19.0/24               205.223.16.0/20

Whois Entry

whois: 402591

IANA has recorded AS21508 as originally allocated by 
/usr/bin/whois -h jwhois.apnic.netr "AS21508\n             
             #
             # 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
             
             
             Comcast Cable Communications, LLC (CCCS)
             
             
             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
             
             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
             
             
             #
             # 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.
             #