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BGP and IPv6 routing coursesSeveral times a year I teach a training course about BGP in association with NL-ix. The course consists of a theory part in the morning and a practical part in the afternoon where the participants implement several assignments on a Cisco router or a VM running the Quagga routing software.
The next dates are:
If you have several people who can benefit from the BGP training course or an IPv6 training course, I can teach a course at your location, in Dutch or English. Please email me to discuss the details.
Interdomain Routing & IPv6 News
Last week, there was a large route leak that involved Swiss hosting company Safe Host and China Telecom. The route leak made internet traffic for European telecoms operators KPN, Swisscom and Bouygues Telecom, among others, flow through Safe Host and China Telecom against the wishes of the telecom operators involved. See this Ars Technica story for more details.
In this post, I'm going to explain how the interaction between the technical and business aspects of internet routing have made this issue so difficult to fix. At the end I'll briefly describe a proposal that I think can actually make that happen.
Geoff Huston has written a post on the APNIC blog congratulating BGP with its 30th birthday. BGP version 1 was published as RFC 1105 in June of 1989. Five years later, the BGP version 4 was published as RFC 1654. And we're still using BGP-4 today, 25 years later! Lots of things, including IPv6 support, were added later in backward compatible ways.
As usual, Geoff's story is comprehensive with lots of interesting details. For instance:
❝From time to time we see proposals to use geo-based addressing schemes and gain aggregation efficiencies through routing these geo-summaries rather than fine-grained prefixes.❞
Sorry about that. 😀 I still think it could work, though.
Well worth a read.
How much bandwidth do I need? Always a hard question. It gets harder as you use more network links, and have to start considering what happens when one or more links fail, leaving you with reduced bandwidth.
The simple way to determine how much total bandwidth you need is to make a guess, and then adjust until the peaks in your bandwidth graphs stay below the 100% line. The more complex answer is that it depends on the bandwidth elasticity of the applications that generate your network traffic.
Applications are bandwidth elastic (sometimes known as "TCP friendly") when they adapt how much data they send to available bandwidth. They're inelastic when they keep sending the same amount of data even though the network can't handle that amount of data. Let's look at a few examples in more detail.
I'm assuming the bandwidth need throughout the day shown in this graph:
Between 21:00 and 22:00, normal bandwidth use reaches a peak of just over 80% of available capacity. But now we lose 25% of our bandwidth, so we have a higher bandwidth need than we can accommodate between 18:00 - 19:00 and 20:00 - 22:00, shown in red below:
Let's look at the behavior of applications with different bandwidth elasticity.
submarinecablemap.com - I just love looking at this stuff.
My Books: "BGP" and "Running IPv6"On this page you can find more information about my book "BGP". Or you can jump immediately to chapter 6, "Traffic Engineering", (approx. 150kB) that O'Reilly has put online as a sample chapter. Information about the Japanese translation can be found here.
More information about my second book, "Running IPv6", is available here.
BGP SecurityBGP has some security holes. This sounds very bad, and of course it isn't good, but don't be overly alarmed. There are basically two problems: sessions can be hijacked, and it is possible to inject incorrect information into the BGP tables for someone who can either hijack a session or someone who has a legitimate BGP session.
Session hijacking is hard to do for someone who can't see the TCP sequence number for the TCP session the BGP protocol runs over, and if there are good anti-spoofing filters it is even impossible. And of course using the TCP MD5 password option (RFC 2385) makes all of this nearly impossible even for someone who can sniff the BGP traffic.
Nearly all ISPs filter BGP information from customers, so in most cases it isn't possible to successfully inject false information. However, filtering on peering sessions between ISPs isn't as widespread, although some networks do this. A rogue ISP could do some real damage here.
There are now two efforts underway to better secure BGP:
The IETF RPSEC (routing protocol security) working group is active in this area.
What is BGPexpert.com?BGPexpert.com is a website dedicated to Internet routing issues. What we want is for packets to find their way from one end of the globe to another, and make the jobs of the people that make this happen a little easier.
Ok, but what is BGP?Have a look at the "what is BGP" page. There is also a list of BGP and interdomain routing terms on this page.
BGP and MultihomingIf you are not an ISP, your main reason to be interested in BGP will probably be to multihome. By connecting to two or more ISPs at the same time, you are "multihomed" and you no longer have to depend on a single ISP for your network connectivity.
This sounds simple enough, but as always, there is a catch. For regular customers, it's the Internet Service Provider who makes sure the rest of the Internet knows where packets have to be sent to reach their customer. If you are multihomed, you can't let your ISP do this, because then you would have to depend on a single ISP again. This is where the BGP protocol comes in: this is the protocol used to carry this information from ISP to ISP. By announcing reachability information for your network to two ISPs, you can make sure everybody still knows how to reach you if one of those ISPs has an outage.
For those of you interested in multihoming in IPv6 (which is pretty much impossible at the moment), have a look at the "IPv6 multihoming solutions" page.
Are you a BGP expert? Take the test to find out!
These questions are somewhat Cisco-centric. We now also have another set of questions and answers for self-study purposes.
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