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Understanding BGP graphs
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Understanding BGP graphs

I am wondering what BGP graphs on HE show exactly?.
What is the relation between those ASNs.
Why the arrows not stopping at certain Tier 1 Providers.



  • rickey318rickey318 Member, Host Rep

    I think its showing the paths it can take to those ASN. The bold one is the most used one. Correct me if wrong :).

  • patrick7patrick7 Member, LIR

    Why should the graph stop at Tier 1 Providers? Most of the ASNs in the world use some Tier 1 as upstream, direct or indirect.

  • DumbledoreDumbledore Member
    edited March 2016

    @rickey318 said:

    I got that part. Im confused about those arrows.

    @patrick7 said:

    Yeah. So it should end at a Tier 1 ISP at right ? like ASN24608 ->ASN6939 (HE)
    But some routes are going beyond Tier 1 ISP, ASN24608 ->AS3320 (Deutsche Telekom)->AS3257(Tinet Spa)

    So what's the difference between those two routes.

  • patrick7patrick7 Member, LIR
    edited March 2016

    HE is not Tier 1 (at least for IPv4).

    If AS3320 (Deutsche Telekom) is an upstream provider of AS24608, it's their job to announce all AS24608 prefixes to all peers/downstreams.

    Thanked by 1Dumbledore
  • @patrick7 said:

    So where these arrows supposed to stop. In some graphs there are arrows/routes from Upstream provider to Tier 1 ISP to another Tier 1 ISP. But in some others it stops at first Tier 1 ISP.

  • patrick7patrick7 Member, LIR
    edited March 2016

    It depends how they peer. And keep in mind, this graph is from the view of Hurricane Electric. It may be incomplete.

  • ZappieZappie Member, Host Rep, LIR

    The data is from routeviews (and so HE claims) meaning the paths are done in normal IX/DC points.

    HE goes out of their way to cut the path and have it start at the first Teir 1 (or what ever defined list they have of transit providers) as the start of their path

    For example (hypothetical path original path)

    Destination ASN <- DC Upstream <- NTT <- HE <- Telia <- DC ASN <- Origin ASN

    will become post processing in HE

    Destination ASN <- DC Upstream <- NTT <- HE <- Telia

    while if we have

    Destination ASN <- DC Upstream <- HE <- Origin ASN

    will become:

    Destination ASN <- DC Upstream <- HE

    and for extra bonuses:

    Destination ASN <- Origin ASN

    Will not even show up on the graph at all and instead will show up as a direct peer in the peer tabs

    Thanked by 1Dumbledore
  • DumbledoreDumbledore Member
    edited March 2016

    @Zappie said:

    Okay. It makes sense now.

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