Type-2 interconnects are fun, but mtu issues are not. When faced with migrating subnets  from one MPLS cloud to another -different AS numbers you see- the three common inter-AS types were taken off the shelf and dusted off…

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Tags: 3600,7600,cisco,IP,linkedin,MP-eBGP,mpls,mtu
Categories: Networking
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I’ll leave the debate to others about running services on routers. As usual ymmv and all that, though besides the obvious objections I think it’s quite cool of my little c877 to proxy DNS and serve what it has locally. Imho, my home DNS config is not heavy enough to warrant rigging up DNS on my Samba server.

My first google tonight led me to an article on the excellent ios hints and tricks site (ioshints.info). Though this is for a full public DNS server it was a little overkill for me, please read this article as well if you do plan to go that route.

My goal was to have my DSL router serve local IP’s for a few public and local domain names. For example this allows me to use sip.djerk.nl as my proxy address in my soft-phone both at home and away.

The following code is what I ended up with.

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Tags: dns,ios,linkedin
Categories: Networking
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Had a nice piece of homework cut out with getting site-to-site ipsec working between a relatives Netgear and my Cisco 877. UniverCD once again provided to be crucial in my understanding and working out what should go where. Thanks to Ilya for reminding me to browse that site rather than just search it.

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Categories: Networking
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Yet another non CCIE post

It appears that Debian Lenny by default only binds to 127.0.0.1 (localhost). I had to add the following two lines to snmpd.conf to get snmpd to listen to external requests.

interface eth0
agentaddress 217.195.248.251:161

I eventually found the solution at debianhelp.org.

Categories: Main blog, Networking
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*Sigh* Took me an hour or two to figure this one out. Cacti now does a ping before actually polling a device for stats. I’m running a small cacti site which had been neglected for a long time. After updating cacti and cleaning up some mess I was confused why one router did get polled and the other’s graphs remained a dumb “nan”.

I debugged and pinged, even installed hping3 to do UDP pings. I don’t want to run cacti as root, especially not on a vhost. So the UDP ping had to work. The pings arrived but still no replies.

Getting sidetracked I noticed that the one router that did work was being hit by SSH login attempts and it’s cpu was spiking. An ACL took care of the break-in attempts but then I noticed that directed broadcasts were made to my server’s segment. So I nailed that down plus proxy-arps when I noticed that the router which had worked before now was causing errors in Cacti as well.

Tracking back I noticed that the UDP ping ‘replies’ were unreachables rather than ICMP replies (doh, how obvious!) . I enabled IP unreachables on both routers again and I was done. It’s amazing how blind one can be at times to the blatantly obvious…

Categories: Main blog, Networking, Work
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Since 12.3 (T?), static routes pointing to interfaces will be advertised by RIP and EIGRP as these static subnets are assumed to be part of the interfaces on which RIP and/or EIGRP is activated.

ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [dhcp] [distance] [name next-hop-name] [permanent | track number] [tag tag]

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Categories: CCIE R&S, Main blog, Networking, Work
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Last weeks news: Networkers EMEA 2008 will be in Barcelona. For the diary: Monday Jan 21st – Thursday 24th.

I’m counting on being there, though untill my manager gives approval and it’s been booked I will not know fur sure…

Categories: Events, Main blog, Networking, Work
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Just a quick note to say that I’m going to Networkers2007.

If you’re going as well and want to meet me then drop me a line, with a suggestion of when you’re free. I don’t think I’ll be able to intentionally run into anyone there, my schedule is way too busy for that.

Suggestions for surviving Networkers are welcome as I’ve never been before.

Categories: Events, Networking, Work
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Got some pictures of Ixia and Spirent equipment in the lab, so check out the gallery if you’re interested.

Categories: Networking, Work
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Right, it’s loading and due to the baud rate of 115200 currently at 13% so I’ve got some time to write this little “note to self”. If anyone else finds this useful then I hope you’re not working away like me at 0:48 in the night.

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Categories: Networking, Work
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Anyone ever heard of ‘Strict Source Routing’ or ‘Loose Source Routing’?

Well it’s in IPv4, CLNP and IPv6, but no-one seems to use it. Please leave a comment if you think I’m wrong! It could be ever so usefull for network monitoring and reporting if one could specify the route a packet should take. One could test, monitor or report on links / paths which one can’t do now due to SFP (Shortest Path First) routing, if only… Sigh

Hint: http://www.iana.org/assignments/ip-parameters

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Categories: CCIE R&S, Networking
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I’m glad Radia Perlman manages to scatter some funny anecdotes into her book “Interconnections”, this one is about the 6 TOS bits in the IP header (page 244):

Some people have affectionately referred to the -IETF Differentiated Services- working group as “200 bald men fighting over 6 combs”.

It’s funny to see the history as she’s describing the future in her book which shows how fast it’s dated. She wrote “Interconnections” in 2000 but it’s still a great ook explaining fundamental issues in a comprehensive manner, my print is a 7th edition from March 2005. Definetely a book to use as network protocol reference due to the many explanations why things are the way they are.

Categories: CCIE R&S, Quotes
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I have decided to add a new category: “Networking quotes”. Here’s the first one, ‘Interconnections, 2nd edition’ page 181:

Priority is an attempt to implement the principles of jealousy and envy in computer networks.
- Tony Lauck

Categories: Quotes
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http://it.slashdot.org/article.pl?sid=06/02/09/1325225&from=rss

Sheridan College Institute of Technology and Advanced Learning has created software that translates network and server activity into music.

Categories: Networking
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