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BGP and IPv6 coursesSeveral times a year I teach two training courses, one about BGP and one about IPv6. The BGP course is half theory and half hands-on practice, and so is the new "IPv6 routing" course. Previously, we did an IPv6 course without a hands-on part.
The courses 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 (in groups of two participants per router).
The next dates are June 2 for the BGP course in Dutch and June 3 for the IPv6 routing course in Dutch. (There will be dates for the courses in English later in 2014.) Go to the NL-ix website to find more information and sign up. The location will be The Hague, Netherlands.
Interdomain Routing & IPv6 News
Interesting presentation by Marc Heuse at Hack in the Box 2012: bugs in IPv6 implementations, differences between IPv4 and IPv6 filtering by large websites, discovering IPv6 systems without brute force address scanning. Did you know that on 63% of networks the ::1 address replies to pings on at least one subnet? And then the
Video at Youtube (64 minutes).
RFC 7059, "A Comparison of IPv6-over-IPv4 Tunnel Mechanisms", was just published. This is a document outlining the various way to tunnel IPv6 packets over (under?) the IPv4 internet. I am one of the three co-authors, together with Sander Steffann and Rick van Rein. We were commissioned to write this document by SURFnet.
We have new dates for the BGP and IPv6 routing training courses:
See the NL-ix website for details.
According to Olivier Bonaventure, Apple is using Multipath TCP (MPTCP) so that iOS 7 devices can communicate with the Siri servers over both Wi-Fi and 3G/LTE at the same time. If you want some background, see this article in the IETF Journal about MPTCP that I wrote in 2009.
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.
"no synchronization"When you run BGP on two or more routers, you need to configure internal BGP (iBGP) between all of them. If those routers are Cisco routers, they won't work very well unless you configure them with no synchronization.
The no synchronization configuration command tells the routers that you don't want them to "synchronize" iBGP and the internal routing protocol such as OSPF. The idea behind synchronizing is that when you have two iBGP speaking routers with another router in between that doesn't speak BGP, the non-BGP router in the middle needs to have the same routing information as the BGP routers, or there could be routing loops. The way to make sure that the non-BGP router is aware of the routing information in BGP, is to redistribute the BGP routing information into the internal routing protocol.
By default, Cisco routers expect you to do this, and wait for the BGP routing information to show up in an internal routing protocol before they'll use any routes learned through iBGP. However, these days redistributing full BGP routing into another protocol isn't really done any more, because it's easier to simply run BGP on any routers in the middle.
But if you don't redistribute BGP into internal routing, the router will still wait for the BGP routes to show up in an internal routing protocol, which will never happen, so the iBGP routes are never used.
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.
IPv6BGPexpert is available over IPv6 as well as IPv4. www.bgpexpert.com has both an IPv4 and an IPv6 address. You can see which one you're connected to at the bottom of the page. Alternatively, you can click on www.ipv6.bgpexpert.com to see if you can connect over IPv6. This URL only has an IPv6 address.
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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