USING WILDCARD MASKS TO FILTER ODD OR EVEN NUMBERED IP ADDRESSES: JUNIPER JUNOS & CISCO IOS

Imagine a user who says they’re only able to access even-numbered IPs in a destination subnet. “Help!”, they say. “I can’t leave the office until this is fixed, and I need to leave now because my seven large sons require their tri-daily feed of protein shakes. They will whither and die unless I nourish them immediately. The fate of my powerful sons is in your hands, and yours alone.” This exact problem came in to us recently. Well, apart from the bit about the large sons.

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IPv6 PREFIXES ON POINT-TO-POINT LINKS – /64 OR /127? WHICH SUBNET MASK TO USE?

When you’re configuring a router for IPv6, what subnet mask should you use on your point-to-point links?
I’ve seen some people use /64s, I’ve seen other people using /127s – and even subnet masks in between. Do any of these people know what they’re doing? Almost certainly not. But hey, that doesn’t mean we can’t work out the pros and cons of both subnet masks – because it turns out that the question of which one to use is actually a bit tricky.

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