1) Can't run CEF. There are some situations under which CEF causes problems. The good news is these are getting to be fewer and fewer every day, but as recently as 6 months ago it would regularly crash routers with some line cards under heavy loads. I expect this reason to disappear completely within another 6 months.
Good arguement. But it seems that no one is doing it.
Also, in the can't run catagory there are some (usually smaller) providers still using 7000's, 4000's, and other (dare I say even 2501's?) for customer attach.
Au contrair, monfrair (sp?!); CEF & CAR is available on many platforms now; we've got it running on 3600's, 4700's, and 7200's. My understanding is that is will also work on 2500's (I was told anything but PowerPC based systems).
2) Can't spare the CPU. Sometimes this has to do with the load of CAR, although generally I expect this is due to other things. If you have 150-200 T1 customers on a 7513 (easy to get with CT3 cards) and you run BGP to even just 25% of them, and you still have RSP2's then you probably don't have CPU to even think about giving to CAR, no matter how little it uses.
As said before, the demonstrable increase in load using CAR is abot 0-2%.
3) Can't manage it. Providers are understaffed with clueful people.
Is this really that hard? access-list 175 permit icmp any any int bleh/bleh rate-limit input access-group 175 128000 8000 8000 conform-action transmit exceed-action drop rate-limit output access-group 175 128000 8000 8000 conform-action transmit exceed-action drop
4) Don't care. I don't mean this in shallow "screw the customer" way. them so they can be perminantly shut off. If it doesn't saturate your links and your routers it's not your problem.
But it could/might. I've seen repeatedly when other downstreams off the same upstream router as us be attacked, the upstreams router usually is unhappy.
5) It's none of their business. This one works people up. The logic goes like this. If my provider CAR's ICMP automatically, why don't they also CAR porn automatically, so it's only a little traffic. Oh, and SPAM, that should be CAR'ed to help reduce it. All e-mail to and from a competitor, that should be CAR'ed really low....
It's a dangerous road to go down.
I don't subscribe to this. Your talking about two different levels of the ISO model :-) -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Atheism is a non-prophet organization. I route, therefore I am. Alex Rubenstein, alex@nac.net, KC2BUO, ISP/C Charter Member Father of the Network and Head Bottle-Washer Net Access Corporation, 9 Mt. Pleasant Tpk., Denville, NJ 07834 Don't choose a spineless ISP; we have more backbone! http://www.nac.net -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --