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Author Topic: Apparent routing issue...  (Read 7449 times)

dfrandin

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Re: Apparent routing issue...
« Reply #15 on: June 18, 2015, 06:51:48 AM »

Paying someone to reach other networks (transit), versus not paying (peering).

Being a noob on the whole big world of internet routing, that is one concept I was never really clear about.. Thanks for putting it so simply.. In other words, Cogent, the bandwidth provider my vps vendor connects to, does not peer with anybody, they require explicit paid contracts "transit" for carrying data to/from other networks, and HE simply says "hey. I'll send your traffic if you send mine.." ie: "peering".. The term used earlier "single-homed behind Cogent" I believe means there *is* no other route to/from the greater internet *other* than thru Cogent... In which case, perhaps I better investigate Sixxs's 4to6 tunnel product if I want to be able to access my vps via ipv6 anytime soon, assuming Sixxs has full routing view...
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broquea

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Re: Apparent routing issue...
« Reply #16 on: June 18, 2015, 07:14:08 AM »

Dfrandin:

No no no no no, Cogent DOES peer with other networks, just more selectively, and in some cases requires others pay them to access their chunk of the internet (paid peering, transit, etc). HE openly peers with anyone that wants to (open peering policy versus selective), or sells transit (no paid peering product). Your provider pays Cogent to access the internet as their transit provider.

Sixxs doesn't actually operate a network, they deploy POPs into other network operators' locations and utilize their connectivity.

evantkh:

I already explained why IPv6 packets can't be routed between HE and Cogent: neither HE or Cogent PAY another network to deliver IPv6 traffic to other networks (transit). And you see those partial Cogent routes because some Cogent customers got an LOA (letter of authorization) issued from Cogent, to re-announce that IPv6 space to other BGP networks; like HE, NTT, etc. You need a better basic understanding of both how BGP works, as well as the overall internet design. The IPv4 example shows exactly how both transit and peering work. Your provider buys transit from their upstream ASN, who then in turn peers off that traffic to the destination either for free or paid (you'll never know).
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evantkh

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Re: Apparent routing issue...
« Reply #17 on: June 18, 2015, 07:31:40 AM »

evantkh:

I already explained why IPv6 packets can't be routed between HE and Cogent: neither HE or Cogent PAY another network to deliver IPv6 traffic to other networks (transit). And you see those partial Cogent routes because some Cogent customers got an LOA (letter of authorization) issued from Cogent, to re-announce that IPv6 space to other BGP networks; like HE, NTT, etc. You need a better basic understanding of both how BGP works, as well as the overall internet design. The IPv4 example shows exactly how both transit and peering work. Your provider buys transit from their upstream ASN, who then in turn peers off that traffic to the destination either for free or paid (you'll never know).

Then why HE.NET is able to see AS174 peers and even the prefixes under this ASN?(on bgp.he.net)

HKIX is a transit!!! or ISPs have direct BGP sessions between each other on HKIX subnet, bypassing HKIX routers?
When I do a BGP route lookup on lg.he.net(selecting Hong Kong as the location), looking up 121.202.1.1, I see HE.NET is directly having BGP session with SmarTone but the next hop is a HKIX IP address.

After looking for some information online, is it correct to say the following?
1. When I am using a transit service from HE.NET, my prefix will be announced to other networks connected with HE.NET with BGP sessions as my own ASN and I can access other networks like Level 3 through HE.NET network. Since HE.NET is peering with Level 3 network, I will not be able to reach other networks behind Level 3.
2. When I am peering with HE.NET, my prefix will not be announced to other networks connected with HE.NET with BGP sessions as my own ASN and I need to add another peering line to Level 3 to access Level 3 network. And also cannot receives routes from other networks in the BGP session with HE.NET.
« Last Edit: June 18, 2015, 07:46:55 AM by evantkh »
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kcochran

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Re: Apparent routing issue...
« Reply #18 on: June 18, 2015, 08:08:46 AM »

bgp.he.net is based off data from public sources, and not views from within HE itself, as to avoid bias.

A network (normally) announces its own routes, and the routes of its customers to a peer.  A network (usually) would announce its complete routes (including those learned from a peer) to a customer.  There are some variances on these, but that's pretty much the rule for 99.9% of those relationships.

So in the case where you have networks A and C peering with B: A sees B's routes, and B's customer's routes; C sees B's routes and B's customer routes; and B sees both A and C's routes and A and C's customer routes.  If B announces A to C, then B is providing transit for A.  If this is not something intended by A, then this is a leak, and extremely poor form for B to do and is a big faux pas (and sometimes cause for A to depeer B).
« Last Edit: June 18, 2015, 08:11:02 AM by kcochran »
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evantkh

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Re: Apparent routing issue...
« Reply #19 on: June 18, 2015, 08:28:21 AM »

bgp.he.net is based off data from public sources, and not views from within HE itself, as to avoid bias.

A network (normally) announces its own routes, and the routes of its customers to a peer.  A network (usually) would announce its complete routes (including those learned from a peer) to a customer.  There are some variances on these, but that's pretty much the rule for 99.9% of those relationships.

So in the case where you have networks A and C peering with B: A sees B's routes, and B's customer's routes; C sees B's routes and B's customer routes; and B sees both A and C's routes and A and C's customer routes.  If B announces A to C, then B is providing transit for A.  If this is not something intended by A, then this is a leak, and extremely poor form for B to do and is a big faux pas (and sometimes cause for A to depeer B).
Thanks.

So if I only use peering, I need to peer with all Tier 1 networks to reach the whole internet, and if I use transit, connect to a few transit providers will be enough. Am I correct?
« Last Edit: June 18, 2015, 08:37:59 AM by evantkh »
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Napsterbater

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Re: Apparent routing issue...
« Reply #20 on: July 21, 2015, 03:56:19 PM »

He just said, because HE nor Cogent pay for IPv6 transit.
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snarked

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Re: Apparent routing issue...
« Reply #21 on: July 21, 2015, 06:39:17 PM »

Cogent is basically IPv6 clueless.  They had an assigned IPv6 allocation for about 6 years go unused because no one enabled IPv6 in their routers.  They'd rather live in an IPv4-only world than upgrade.
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