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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Question about 223/8
On Tue, 29 Apr 2003 [email protected] wrote: > Imagine you have a device that uses lots of addresses but considers them > to be sequential numbers rather than bit patterns. For instance, this > device could be configured with a starting number and then dole out > sequential numbers to connections based on that starting number. This is > how a lot of terminal servers work. Have you configured any terminal/access servers recently? > Imagine that you give the terminal server a number like 223.255.255.200 as > the starting number to assign to dialup connections and that terminal > server has a 32 port card installed. Then one day an engineer installs a > second 32 port card. The terminal server continues to function just fine > until one day when it tries to assign 223.255.255.255 to an incoming call > followed by assigning 224.0.0.0 to the next call. Suddenly you have all > kinds of wierdness breaking out with mysterious broadcast traffic and > multicast traffic coming from the device. But it only happens for short > bursts during the busiest times of the day. What the heck is going on!? I'd call that incompetence. A starting number of 200 + 64 ports = too small an IP pool. The cisco gear I use is a bit smarter and when configuring IP pools, both the starting address and ending address are specified (and you can specify multiple non-contiguous ranges). I generally omit /24 network/broadcast addresses from IP pools because too much software assumes everything's a /24 and if you assign someone a /24 broadcast IP, they're going to receive some (maybe alot of) junk traffic depending on what's in the other subnets of the /24 they're in. > Maybe that's why 223.255.255/24 should be forever reserved. That's way too stupid a reason. That better not be it. ---------------------------------------------------------------------- Jon Lewis *[email protected]*| I route System Administrator | therefore you are Atlantic Net | _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
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