For the second part of this post, I will be covering a couple of scenarios by changing the default values of RIPv2 timers. First scenario is when the Flush After time is configured to last longer than Holddown timer in which case, the route will get flushed when the Holddown timer expires even though the Flush After timer is still on. This is the RIPv2 config for R1: Another look at the graphical representation of how timers look like now. The red line demonstrates when the route should be flushed from the routing table Again, focusing on how R1 receives network 126.96.36.199, I will make R4's gig1/0 passive. Network 5.5.5 should remain in the routing table for about 6min before it gets
RIPv2 is probably one of the simplest routing protocols. Even its timers are often described as 'basic' - but how basic are they? I mean sure, we know 'Update timer' is 30 seconds, 'Invalid After' timer is 180 seconds, 'Holddown' timer is 180 seconds and finally 'Flush After' timer is 240 seconds. However, I found that those timers and their function are somewhat poorly, or even wrongly, documented in some online posts. As always, no better way to understand any technology than run it in a lab. I'm going to explain, in details, RIPv2 timers. First, starting with this simple network: Each one of those routers has a loopback interface matches the router number. For example, R1 has loopback1: 188.8.131.52/32, R2 has loopback2:
Yesterday you said tomorrow.......SO JUST DO IT!
As I mentioned in the previous L3VPN posts, those were using one specific architecture to connect two ISPs to each other, which is called Back to Back VRFs where a VRF is needed for each customer in both ISPs networks. Of course this is one way of making this to work. Another design is called carrier supporting carrier which I'm going to explain in this post. I'm going to use the same previous design with some slight changes, HERE is the complete diagram. There are no changes in the customer sites configuration and they are exactly as I left them in the previous MPLS VPN series, so I am not going to copy their configuration here. All the configuration changes happen in both ISPs