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Multihomed
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Multihomed

nfnnfn Veteran

Hi,

Are there any online tools that we can use to see if a provider is multihomed?

Thanks

Comments

  • J1021J1021 Member

    Are you seeing any particular issues?

  • nfnnfn Veteran

    No, I was searching Google for kvm providers in UK just for fun, and found some which own data centers, so I would like to see if these dc's are multihomed or not.

  • Bgp.he.net

    Thanked by 1cochon
  • BruceBruce Member

    @nfn said:
    No, I was searching Google for kvm providers in UK just for fun, and found some which own data centers, so I would like to see if these dc's are multihomed or not.

    which ASN ?

  • nfnnfn Veteran

    I don't have a specific asn. How can I see at bgp.he.net if the provider DC is multihomed?

  • paste an ip in

  • BruceBruce Member
    edited July 2015

    @nfn said:
    I don't have a specific asn. How can I see at bgp.he.net if the provider DC is multihomed?

    google "< provider > asn"

    example:

    http://bgp.he.net/AS62240#_graph4

    Thanked by 1Clouvider
  • Though you cannot put too much trust in that - If space is announced with a lot of prepends on one ISP it is essentially singlehomed with "only" a backup-on-fault system.

  • ClouviderClouvider Member, Patron Provider
    edited July 2015

    @Willim not necessarily as, for example, you have no idea how the outbound routing looks like and there is no way of knowing externally unless the provider provides a looking glass. Outbound routing is much more important in a hosting scenario.

    @William said:
    singlehomed with "only" a backup-on-fault system.

    That's stil multihomed.

  • BruceBruce Member

    @william, this is single homed:

    Thanked by 1Clouvider
  • Yes, thanks, i know how a multhihomed network looks like :)

    Thanked by 2Bruce Clouvider
  • ClouviderClouvider Member, Patron Provider

    @William that's Anycasted ;)

  • Not only (1 /24 is unicast (UK) and ~600 announced /48 are unicast v6, while a /23 is anycast and a /48 v6 is as well)

  • ClouviderClouvider Member, Patron Provider

    So two different network policies on one ASN? :)?

  • patrick7patrick7 Member, LIR

    600 /48? You should be arrested for that deaggregation.

  • ClouviderClouvider Member, Patron Provider

    @patrick7 in their case it might be technically justified. :)

  • patrick7 said: 600 /48? You should be arrested for that deaggregation.

    Not my problem in the end - The v6 routing table will grow far more anyway as /48 is the default PI/Direct Allocation size.

    Anyway, my ~600 /48s are not global - Only sent to HE, which is fine with what and how i do it (and their routers handle it fine) - 90% of the routes are not further distributed as HE sends out a /43 announce (/48s are filtered) per location for global access and my other upstreams do only get the /43s announce, for worst case scenario (and some idiotic eyeball networks with filters larger than /43) i also announce it as /32 and do my own routing between locations (tunnels).

    600 is also not a large amount in total numbers (and by end of year it's easily 1000+) - i use 2-3 /43 (64-96 /48) per location currently and assign /47s to enduser tunnels (with 1 /48 routed and another for future use).

    Clouvider said: So two different network policies on one ASN? :)?

    More than 2 - Anycast for R4, Anycast for me, Unicast for me, Unicast for a few customers, Unicast for my tunnelbroker and downstream BGP for Tunnels with BGP.

    I can use one ASN for everything like that, from external PoV it makes not really any difference (and RIPE approves that to save ASNs even though with 4byte this is now irrelevant).

  • ClouviderClouvider Member, Patron Provider
    edited July 2015

    William said: I can use one ASN for everything like that, from external PoV it makes not really any difference

    Technically it works, however it's not standard. Some good networks do BGP optimisation based on external factors, like latency and packet loss. Some do it on per AS basis. Heaving it set up this way undermines those metrics, and hence hurts potential benefits that could otherwise be achieved.

    Nevertheless, nothing to make a fuss about, but while ASNs are essentially free, why not make it one routing policy per ASN as it was supposed to be :)?

    Thanked by 1William
  • WilliamWilliam Member
    edited July 2015

    Clouvider said: Technically it works, however it's not standard. Some good networks do BGP optimisation based on external factors, like latency and packet loss. Some do it on per AS basis. Heaving it set up this way undermines those metrics, and hence hurts potential benefits that could otherwise be achieved.

    OVH, Softlayer and Leaseweb also use one ASN globally, as do Level3, Cogent, Telecom Italia...pretty much any Tier1...

    I also dont need to care much about networks that do optimization by AS as these are mainly DCs (and then only the ones with the overpriced FCP) while my customers are 95%+ end-user ISPs that barely do any optimization at all. Worst case i can still contact the ISP if there are issues.

    I could get a bunch more ASNs from RIPE (and i have some more, i.e. 61163) but it is easier from management/software PoV to use one globally, the other RIRs partly bill by ASN so it would cause me much higher costs to use ARIN/APNIC ASNs for their respective footprint.

    Thanked by 1Clouvider
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