Thus spake Alan Cox
>> 3) My knowledge of the PC architecture is probably not the highest on
>> the list -- assuming a 100 MHz bus with 100Mhz SDRAM slots -- are
>> there any concerns on the actual bus performance? I know silly
>Yes. Once you hit 4x100Mbit you are on the limit probably. PC's are not
>good GigE routers
Uhm...my understanding (and I'm not up on the latest PC architecture
specs) is that PCI maxes out at 400Mbps...that means that a Linux router
will max out a PCI bus (assuming a PCI bus which is pretty ubiquitous)
at 2 Fast ethernet cards (100Mbps full-duplex), not 4. If you're only
running half-duplex, you could get up to 4 fast ethernet at wire speed
on a PCI bus.
>> a large problem since last I checked a full table was roughly 32
>> Meg -- but what I am wondering is -- how well is BGP supported in
>> Linux currently?
>Gated and Zebra do BGP4. I don't know how well
Never used zebra, but I refuse to touch gated...that's got the most
horrid configuration I've ever seen.
At the risk of taking this further off topic...
Some other thoughts on things you're sacrificing moving to a Linux based
router from Cisco.
- memory copies. As I understand it, to switch a packet through a Linux
router, there are at least 2 memory copies....the packet is received and
stored in the nic buffer...from there it's copied into main memory...I'm
assuming the Linux kernel is very efficient and doesn't do any copies of
its own...from there its copied into the outgoing nic's packet buffer.
Cisco hardware...being designed with IOS in mind, allows IOS to do zero
memory copies....the packet is read from the incoming nic's packet
buffer directly out the outgoing nic.
- extensive switching support. To my understanding, you can't have a
linux box with 4 ethernet cards and bridge between eth0 and eth1, and
then bridge between eth2, and eth3, and then route between the eth0/1
combo and the eth2/3 combo. IOS handles that with no problem. Other
"switching" features that to my best knowledge are missing on Linux
(though this can obviously change) VRRP, SRB and SRTB, briding over
wan links, circuit-groups, and I'm probably missing more. These are
just switching features that you get on IOS that you don't (yet) have in
Linux...no...not everyone needs them, but some of those are pretty
significant.
Someone in this thread mentioned that IOS doesn't support encrypted
access methods such as ssh...FWIW, its new, but 12.0S does have ssh
support in it.
I'm a big fan of Linux...use it whenever possible...but let's not try
and say that Linux is the perfect platform for every situation...its
not. Its a great OS. But for routing....for anything about T1
speeds...I'm going with Cisco for reliability reasons (yes, I know, the
LRP doesn't even need a hard drive...boots off a floppy, but I've found
floppy drives to be *huge* problems for routers in lights-out
facilities...used to have some old Xyplex routers that booted off
floppies and they were an absolute nightmare because the floppies died
on a regular basis).
--
Jeff McAdams Email: [EMAIL PROTECTED]
Head Network Administrator Voice: (502) 966-3848
IgLou Internet Services (800) 436-4456
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