I was watching INE videos about RIP and when I reached the RIP Authentication video, I apparently forgot about the key number must match requirement when using MD5. To be honest, it wasn’t the only one I forgot about RIP. Heck, I usually forget what I read last night! It’s a constant struggle that I deal with every single day. I think I need a flash drive or the “Limitless” pill so that I can remember everything I read, but I digress.
OSPF behavior using different interface types.
|Interface Type||Uses DR/BDR?||Default|
|More than Two|
in the Subnet?
|Nonbroadcast 2 (NBMA)||Yes||30||Yes||Yes|
1 Default on Frame Relay point-to-point subinterfaces.
2 Default on Frame Relay physical and multipoint subinterfaces.
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Ever seen this error message %TUN-5-RECURDOWN: Tunnel1 temporarily disabled due to recursive routing? The most common reason for this error is that the router is trying to route to the tunnel destination address using the tunnel interface itself. This error message will keep flooding your router until someone fixes the misconfiguration of the router. This will also mean that your tunnel interface will keep flapping until fixed.
Let’s take a look at a scenario in which recursive routing is being experienced. In this particular environment, there are several remote branches that will need to establish a GRE tunnel to the headend. For simplicity, the diagram only shows two remote branches and the configuration only shows the headend and a remote branch. Please ignore the IP addressing as I just picked random numbers. The 172.18.0.0/16 address, however, has been assigned to be the serial interfaces of the remote branch routers.
Here are the configuration of the enterprise routers:
When you’re building a Cisco home lab, make sure to buy switches and/or routers that will satisfy the requirements of the track you’re currently studying for. You may also want to future proof your home lab for other Cisco tracks. Future proofing was one of the reasons why I didn’t buy 1841 for my lab and bought 2801 instead. 1841s will not satisfy the requirements of Voice track, which is one of the Cisco tracks that I would like to learn more about. Anyway, CCNP R&S (Routing and Switching) and CCIE R&S requires you to know IPv6. While CCNP does not specifically require to run IPv6 on 3560, it will most likely be used in the CCIE lab exam. I do know that INE materials require you to enable IPv6 on Catalyst 3560 to practice and master the topic.