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I've been running BGP at home for the last 10 years, and in my area, most ISPs prefer to use Dedicated Internet Access (DIA) for BGP sessions. Fortunately, I li

I've been running BGP at home for the last 10 years, and in my area, most ISPs prefer to use Dedicated Internet Access (DIA) for BGP sessions. Fortunately, I live in a place where there are a few smaller ISPs with around 2000-3000 customers that are willing to run BGP with me as a home user. They're impressed that I have BGP, ASN, and IPs as a home user, and I think it's pretty cool too. Additionally, running one more BGP session makes their network appear larger, so they benefit as well. I currently have a BGP session with one of my ISPs on the 15 euro plan (1 Gbps), and another local ISP is giving me 10 Gbps for free because I'm a test user. Both of these ISPs support BGP, and it's amazing that I can have BGP sessions as a home user. However, it can be challenging to speak with regular sales reps who may not be familiar with BGP. It takes persistence and some effort to get to the network administrator. It's frustrating that some ISPs make it artificially difficult for home users to obtain a BGP session, even when they're not asking for SLAs or dedicated connections. Technically, you can even run a BGP session over dial-up. It seems like these restrictions are in place to squeeze more money from customers. It's no secret that we've run out of IPv4 addresses, and I happen to have a /24 subnet just for myself. Even with all my usage, I barely use half of it. There's no rule that says ISPs should only accept /24 or shorter prefixes, and this is contributing to the depletion of IPv4 addresses. I would happily announce a /25 and return the other /25 to the world, but I must have a /24 to do it. This practice of requiring /24 subnets may have made sense in the past to preserve router memory, but with today's technology, it's nonsensical and only serves to artificially deplete available IPv4 addresses.

traceroute66 4y ago
> It's frustrating that some ISPs make it artificially difficult for home users to obtain a BGP session Don't worry, it can be frustrating for businesses too ! Cogent famously nickle-and-dime their customers and consider BGP to be a chargeable extra, even on their IP Transit product which is somewhere where you would expect BGP to be a given. Of course whether you should do business with Cogent is another matter, especially given their spammy cold-calling tactics, seemingly once you're on their list you can never get off it.
throwaway894345 4y ago
I have a super rudimentary understanding of what BGP is (it allows you to advertise addresses something something), but I don't really understand why it's useful and thus I'm finding TFA to be a little inaccessible. Could you provide some context about what you're using BGP for (what is your use case; what does it enable for you; etc) such that it might fill in some gaps for me?
- linsomniac 4y ago
  BGP is what "the Internet" uses to say what IP addresses can be reached over the various network links that connect different providers. If you had links to two different providers, you would talk BGP to them and say "You can reach this set of IP addresses via me." They then propagate that announcement on to other providers that they connect to. This is done via ASNs (Autonomous Systems Numbers), like 32150 (my old ASN). Each hop along the way gets their ASN tacked on. It's like a flood-fill to all the BGP routers in the world. When you "traceroute", you see IP hops along the way, but the ISPs routers choose links based on this list of autonomous paths (among other things). Basically, a AS-level traceroute is built into the BGP routing information. At it's most basic, a path is selected based on the shortest AS path (traceroute, but at the organization level rather than IP level); the fewest number of networks the traffic has to traverse. If a link goes down (either because of a network failing, or because of administrative reasons), traffic will eventually switch over to another way of reaching the destination. You can also do things like pad the AS path with multiple copies of your AS to cause traffic to switch to another link more frequently, as a kind of primitive load balancing.
  - bogomipz 4y ago
    >"If you had links to two different providers, you would talk BGP to them and say "You can reach this set of IP addresses via me." There is really need to do this is many cases though. If all you are looking for is connectivity redundancy you can just take the default routes from two ISPs and configure floating static routes on your router and not worry about BGP at all. >"This is done via ASNs (Autonomous Systems Numbers), like 32150 (my old ASN). Each hop along the way gets their ASN tacked on. It's like a flood-fill to all the BGP routers in the world." Each hop does not get its own ASN tacked on. This only happens when crossing an AS boundary i.e at eBGP speaker. There are generally many hops inside an AS.
notyourday 4y ago
> This practice of requiring /24 subnets may have made sense in the past to preserve router memory, but with today's technology, it's nonsensical and only serves to artificially deplete available IPv4 addresses. You should be surprised about how much of the internet still runs on gear from late 1990s
icedchai 4y ago
You're lucky. There are basically no small ISPs around here anymore. It's the cable company (DOCSIS) or telco (fiber, or DSL if you're unlucky.) Without paying for an enterprise grade connection, it would be impossible to get a BGP session through either. I also have a /24 for myself. I've had it since the mid-90's, from the InterNIC days, predating ARIN. I've gone years without using any of the addresses. Currently it's routed to my home lab. I'm doing BGP through a couple VPSes, then tunneling it back.
- hattmall 4y ago
  I have a /24 as well, can you point me to any links or tutorials of how I can actually use it with my home connections
  - icedchai 4y ago
    This person has a good overview: https://varunpriolkar.com/2018/12/bgp-on-a-shoestring-the-definitive-guide/ https://varunpriolkar.com/2018/12/bgp-on-a-shoestring-the-de... Basically, you get an ASN, find a BGP-friendly VPS or colo, announce your /24, and tunnel it back to your home.
bogomipz 4y ago
There seems to be a lot of misconceptions in your post. >"Additionally, running one more BGP session makes their network appear larger, so they benefit as well." This doesn't make any sense. The number of "BPG sessions" is not a metric any ISP thinks about. A BPG session is just TCP connection. The number of prefixes an ISP is advertising might be something they care about however but for smaller ISPs that doesn't really matter as they are just customers of the Tier 1 ISPs and that just requires paying the Tier 1 ISP. It has nothing to do with the number of sessions or prefixes. I could have a single /22 prefix for my company and the Tier 1 ISP will still sell me the same service. >"There's no rule that says ISPs should only accept /24 or shorter prefixes, and this is contributing to the depletion of IPv4 addresses. I would happily announce a /25 and return the other /25 to the world, but I must have a /24 to do it." Well yes there is. Many ISPs will generally not accept routes smaller than a /24. They configure filter-lists that prevent those routes from being accepted. The reason for this is to reduce the size of the global routing table. Each prefix has to be stored in TCAM(memory) on a router. There have been many incidents where older routers couldn't handle the number of routes in the global routing table and caused them outages. See: https://arstechnica.com/information-technology/2014/08/internet-routers-hitting-512k-limit-some-become-unreliable/ https://arstechnica.com/information-technology/2014/08/inter... and https://www.inap.com/blog/growing-pains-internet-global-routing-table/ https://www.inap.com/blog/growing-pains-internet-global-rout... Further if you have a /24 you can certainly advertise 2 /25s to the same upstream ISP if you have more than one transit connection with them. In fact this is exactly how do traffic engineering. >"It's frustrating that some ISPs make it artificially difficult for home users to obtain a BGP session, even when they're not asking for SLAs or dedicated connections." This because home users absolutely don't need to run BGP! You just take a default route from your ISP and you're done with it. There is not point in running BGP if you are single-homed! You can't do any traffic engineering on it or influence the way upstream ISP route traffic to you. From the hobbyist point view it would be extremely boring. What can you actually do with it? View the global routing table? You can do this without ever running BGP by using a public looking glass server[1]. There is no incentive for ISP whose business is selling internet connectivity to cultivate a hobbyist community. [1] https://www.bgp4.as/looking-glasses https://www.bgp4.as/looking-glasses

traceroute66 4y ago

> It's frustrating that some ISPs make it artificially difficult for home users to obtain a BGP session Don't worry, it can be frustrating for businesses too ! Cogent famously nickle-and-dime their customers and consider BGP to be a chargeable extra, even on their IP Transit product which is somewhere where you would expect BGP to be a given. Of course whether you should do business with Cogent is another matter, especially given their spammy cold-calling tactics, seemingly once you're on their list you can never get off it.

throwaway894345 4y ago

I have a super rudimentary understanding of what BGP is (it allows you to advertise addresses something something), but I don't really understand why it's useful and thus I'm finding TFA to be a little inaccessible. Could you provide some context about what you're using BGP for (what is your use case; what does it enable for you; etc) such that it might fill in some gaps for me?

linsomniac 4y ago
BGP is what "the Internet" uses to say what IP addresses can be reached over the various network links that connect different providers. If you had links to two different providers, you would talk BGP to them and say "You can reach this set of IP addresses via me." They then propagate that announcement on to other providers that they connect to. This is done via ASNs (Autonomous Systems Numbers), like 32150 (my old ASN). Each hop along the way gets their ASN tacked on. It's like a flood-fill to all the BGP routers in the world. When you "traceroute", you see IP hops along the way, but the ISPs routers choose links based on this list of autonomous paths (among other things). Basically, a AS-level traceroute is built into the BGP routing information. At it's most basic, a path is selected based on the shortest AS path (traceroute, but at the organization level rather than IP level); the fewest number of networks the traffic has to traverse. If a link goes down (either because of a network failing, or because of administrative reasons), traffic will eventually switch over to another way of reaching the destination. You can also do things like pad the AS path with multiple copies of your AS to cause traffic to switch to another link more frequently, as a kind of primitive load balancing.
- bogomipz 4y ago
  >"If you had links to two different providers, you would talk BGP to them and say "You can reach this set of IP addresses via me." There is really need to do this is many cases though. If all you are looking for is connectivity redundancy you can just take the default routes from two ISPs and configure floating static routes on your router and not worry about BGP at all. >"This is done via ASNs (Autonomous Systems Numbers), like 32150 (my old ASN). Each hop along the way gets their ASN tacked on. It's like a flood-fill to all the BGP routers in the world." Each hop does not get its own ASN tacked on. This only happens when crossing an AS boundary i.e at eBGP speaker. There are generally many hops inside an AS.

notyourday 4y ago

> This practice of requiring /24 subnets may have made sense in the past to preserve router memory, but with today's technology, it's nonsensical and only serves to artificially deplete available IPv4 addresses. You should be surprised about how much of the internet still runs on gear from late 1990s

icedchai 4y ago

You're lucky. There are basically no small ISPs around here anymore. It's the cable company (DOCSIS) or telco (fiber, or DSL if you're unlucky.) Without paying for an enterprise grade connection, it would be impossible to get a BGP session through either. I also have a /24 for myself. I've had it since the mid-90's, from the InterNIC days, predating ARIN. I've gone years without using any of the addresses. Currently it's routed to my home lab. I'm doing BGP through a couple VPSes, then tunneling it back.

hattmall 4y ago
I have a /24 as well, can you point me to any links or tutorials of how I can actually use it with my home connections
- icedchai 4y ago
  This person has a good overview: https://varunpriolkar.com/2018/12/bgp-on-a-shoestring-the-definitive-guide/ https://varunpriolkar.com/2018/12/bgp-on-a-shoestring-the-de... Basically, you get an ASN, find a BGP-friendly VPS or colo, announce your /24, and tunnel it back to your home.

bogomipz 4y ago

There seems to be a lot of misconceptions in your post. >"Additionally, running one more BGP session makes their network appear larger, so they benefit as well." This doesn't make any sense. The number of "BPG sessions" is not a metric any ISP thinks about. A BPG session is just TCP connection. The number of prefixes an ISP is advertising might be something they care about however but for smaller ISPs that doesn't really matter as they are just customers of the Tier 1 ISPs and that just requires paying the Tier 1 ISP. It has nothing to do with the number of sessions or prefixes. I could have a single /22 prefix for my company and the Tier 1 ISP will still sell me the same service. >"There's no rule that says ISPs should only accept /24 or shorter prefixes, and this is contributing to the depletion of IPv4 addresses. I would happily announce a /25 and return the other /25 to the world, but I must have a /24 to do it." Well yes there is. Many ISPs will generally not accept routes smaller than a /24. They configure filter-lists that prevent those routes from being accepted. The reason for this is to reduce the size of the global routing table. Each prefix has to be stored in TCAM(memory) on a router. There have been many incidents where older routers couldn't handle the number of routes in the global routing table and caused them outages. See: https://arstechnica.com/information-technology/2014/08/internet-routers-hitting-512k-limit-some-become-unreliable/ https://arstechnica.com/information-technology/2014/08/inter... and https://www.inap.com/blog/growing-pains-internet-global-routing-table/ https://www.inap.com/blog/growing-pains-internet-global-rout... Further if you have a /24 you can certainly advertise 2 /25s to the same upstream ISP if you have more than one transit connection with them. In fact this is exactly how do traffic engineering. >"It's frustrating that some ISPs make it artificially difficult for home users to obtain a BGP session, even when they're not asking for SLAs or dedicated connections." This because home users absolutely don't need to run BGP! You just take a default route from your ISP and you're done with it. There is not point in running BGP if you are single-homed! You can't do any traffic engineering on it or influence the way upstream ISP route traffic to you. From the hobbyist point view it would be extremely boring. What can you actually do with it? View the global routing table? You can do this without ever running BGP by using a public looking glass server[1]. There is no incentive for ISP whose business is selling internet connectivity to cultivate a hobbyist community. [1] https://www.bgp4.as/looking-glasses https://www.bgp4.as/looking-glasses