nanog mailing list archives
Re: If you have nothing to hide
From: Eric Osborne <eosborne () cisco com>
Date: Mon, 5 Aug 2002 23:49:20 -0400
On Mon, Aug 05, 2002 at 06:46:59PM -0400, bdragon () gweep net wrote:
Validation of routing policy to ensure others aren't abusing you (pointing default, for example). As for orders of magnitude, once an IP option is in a packet, the damage is essentially done, otherwise looking up the path to an address in the options is no more impactive than looking up the address in the original destination field.Well, no. Not really. First off, following the 80/20 rule (or in this case 99.x/(100-99.x) rule) says that hardware implementations which get optioned packets punt them to software. This is at every hop. Second, the IP source route is a stack of IP addresses, which must be modified at every hop. This implies not just software forwarding, but also significantly more work than an IP lookup.As I said, once the option is in the packet, the damage is done. If the performance sucks for the person using the source-routing, who cares, assuming packets without IP options are forwarded without delay.
You care...the more work you do in SW, the less time your SW has to do useful things like make sure the HW is talking to the control plane. This is either an argument for more HW support for optioned packets or less optioned packets on the network, depending on your perspective.
If I'm not mistaken, most (if not all) vendors still punt the packets with source-routing options to software, even if they end up dropping the packet due to administrative decision.
Yeah, generally, although it could certainly depend not only on vendor but on engine...:) eric
eric
Current thread:
- Re: If you have nothing to hide, (continued)
- Re: If you have nothing to hide Valdis . Kletnieks (Aug 05)
- Re: If you have nothing to hide Jeffrey Haas (Aug 05)
- Re: If you have nothing to hide Gerardo A. Gregory (Aug 05)
- Re: If you have nothing to hide Sean Donelan (Aug 06)
- Re: If you have nothing to hide Simon Waters (Aug 05)
- Re: If you have nothing to hide fingers (Aug 05)
- Re: If you have nothing to hide Henry Yen (Aug 05)
- Re: If you have nothing to hide bdragon (Aug 05)
- Re: If you have nothing to hide Eric Osborne (Aug 05)
- Re: If you have nothing to hide bdragon (Aug 05)
- Re: If you have nothing to hide Eric Osborne (Aug 05)
- Re: If you have nothing to hide Eric Osborne (Aug 05)
- Re: If you have nothing to hide bdragon (Aug 08)
- Re: If you have nothing to hide gg (Aug 09)
- 59% of dweebs suffer from 'False Authority Syndrome (Re: If you have nothing to hide) Len Rose (Aug 09)