by Tony Mattke on February 21, 2011
Striving to reach that last 9? Looking for a way to increase your uptime while still being able to do maintenance on your network? Wish you could shutdown your OSPF neighbors like your BGP peers? Ok, enough sales talk. Achieving HA uptimes when you need to do maintenance is far from simple, even if you tweak your hello timers, or use some fast detection protocol like BFD it still takes time for your protocols to converge. A much better solution would be gracefully notifying a router’s neighbors of a dramatic cost increase on all of it’s interfaces which would force an SPF calculation while the router is still online forwarding packets.
Welcome RFC 3137 — OSPF Stub Router Advertisement is a feature implemented in Cisco IOS release 12.2(4)T and 12.3. To force our router into stub status we can use the max-metric router-lsa router configuration command which changes the OSPF metric for all non-stub interfaces on the router to 65535.
The new metric in the LSA does not cause the path to be ignored, it just increases the cost. The other routers in the network will select any alternate paths (if available).
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by Tony Mattke on October 4, 2009
As a follow up to my JunOS Olive tutorial, I made a demonstration video that shows Multicast functioning via OSPF to another Olive and an ImageStream VM.
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by Tony Mattke on May 9, 2009
Recently one of my clients asked me to help resolve an issue at an aggregation point on their network. They had several connections that converged onto a single unlicensed link on their network, not only was the link saturated, but it had lots of bi-directional traffic going across it. While I would’ve preferred to move them to a licensed setup, the associated costs were astronomical when compared to implementing a little ospf-fu.
The basic idea here is to create two ospf paths we can use, and on each side ‘de-prefer’ one of them. This allows us to one radio for sending data, and one for receiving data. (although OSPF traffic will still be sent and recieved across either link independently, it should not cause you any issues) This setup creates a simulated full-duplex link. Lets take a look at an example that will for work for Cisco or ImageStream (Quagga) routers…
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