Re: [Hampshire] Black Hole detection
On 03/20/12 11:43, James Courtier-Dutton wrote: Hi, Sometimes, a network will have black holes in the sense that say, packet sizes up to 0-1400 get through, 1400-1404 fail, and 1405-1500 get through. You can find these holes using ping with DF bit set and various sized pings. If you find problems, you then fix them so all sizes get through. Does anyone know of a tool that will automatically scan all packet sizes and report the result? I use libipq (on Linux boxes) with Perl (most of the time) or C. Its inline with something like : iptables -A OUTPUT -j QUEUE which passes packets to userspace. Then I write some code to inspect the packets and, if needed, manipulate them. Its actually the onld fashioned way, AFAIK netlink is the way to go nowadays. Either way, its really worth a look. Regards, Zak. ps. James, i'm testing those boards this week, will let you know what choices are available. -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Black Hole detection
On 20 March 2012 19:01, Anton Piatek wrote: > How or why does this problem occur? I can't think of an explanation. > It normally happens when devices are configured wrongly in the network. For example, VPN boxes that do IPSEC seem to sometimes cause problems, as well as bugs in some Cisco Routers. For example, I had a black whole problem with a certain large carrier's MPLS WAN network. It turned out to be a hardware bug in one of the Line cards in some big Cisco Core Router. Replacing the line card with a more up to date one from Cisco cured the problem. It happens often enough for me to make a black hole test standard before I let a customer's network go live over a new network link. Kind Regards James -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Black Hole detection
How or why does this problem occur? I can't think of an explanation. Anton -- Anton Piatek (sent from my phone, please excuse any typos) email: an...@piatek.co.uk blog/photos: http://www.strangeparty.com pgp: [74B1FA37] (http:// www.strangeparty.com/anton.asc) No trees were destroyed in the sending of this message, however, a significant number of electrons were terribly inconvenienced. On Mar 20, 2012 11:43 AM, "James Courtier-Dutton" wrote: > Hi, > > Sometimes, a network will have black holes in the sense that say, > packet sizes up to 0-1400 get through, 1400-1404 fail, and 1405-1500 > get through. > You can find these holes using ping with DF bit set and various sized > pings. > If you find problems, you then fix them so all sizes get through. > Does anyone know of a tool that will automatically scan all packet > sizes and report the result? > > Kind Regards > > James > > -- > Please post to: Hampshire@mailman.lug.org.uk > Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire > LUG URL: http://www.hantslug.org.uk > -- > -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] One two, one two
On 20/03/12 09:37, Tony Whitmore wrote: Just checking that this thing is still on. Nothing in a week!? -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk -- You think a week is bad? Try 3 years or so! I realised the other day that I never got around to resubscribing after changing email address 3 or 4 years ago..wondered why my LUG folder was so quiet. In my defence though..I have been kinda busy with family issues :) Glenn -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] One two, one two
On Tue, Mar 20, 2012 at 10:16 PM, Victor Churchill wrote: > >> There seems to be a bit of feedback :-) > > > scrreeEEEeeekkk!! Who goes there? -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] One two, one two
> There seems to be a bit of feedback :-) > scrreeEEEeeekkk!! -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
[Hampshire] Humble bundle: games!
In case you haven't seen it, the latest Humble Bundle is out, and features games for linux and android (and other OSs). It is worth noting that Linux users are the most generous when it comes to choosing how much to pay. See http://www.humblebundle.com/ for more Anton - Anton Piatek email: an...@piatek.co.uk blog/photos: http://www.strangeparty.com gpg: [74B1FA37] (http:// www.strangeparty.com/anton.asc) No trees were destroyed in the sending of this message, however, a significant number of electrons were terribly inconvenienced. -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] One two, one two
There seems to be a bit of feedback :-) -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
[Hampshire] Black Hole detection
Hi, Sometimes, a network will have black holes in the sense that say, packet sizes up to 0-1400 get through, 1400-1404 fail, and 1405-1500 get through. You can find these holes using ping with DF bit set and various sized pings. If you find problems, you then fix them so all sizes get through. Does anyone know of a tool that will automatically scan all packet sizes and report the result? Kind Regards James -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] One two, one two
you have clearance Clarance! On Tue, Mar 20, 2012 at 9:40 AM, James Bensley wrote: > On 20 March 2012 09:37, Tony Whitmore wrote: >> Just checking that this thing is still on. Nothing in a week!? > > Roger roger. > > -- > Please post to: Hampshire@mailman.lug.org.uk > Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire > LUG URL: http://www.hantslug.org.uk > -- -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] One two, one two
On 20 March 2012 09:37, Tony Whitmore wrote: > Just checking that this thing is still on. Nothing in a week!? Roger roger. -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
[Hampshire] One two, one two
Just checking that this thing is still on. Nothing in a week!? -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
