Summary : Creating multiple aliases on a qfe card

From: Perttunen, Bruce <>
Date: Tue Jan 29 2002 - 11:04:30 EST
Here is my original post......

== I have a dual processor E420R with a Quad Fast Ethernet card.  I am using
two interfaces on == the card and have two aliases set up on the first
interface.  They look like...
== qfe0
== qfe0:1
== qfe0:2
== qfe3
== I have been asked to create yet another alias on qfe0 (qfe0:3) but I am
concerned about 
== doing this.  Is there anything I should be worried about?  Is there a
limit to the number
== of aliases on a port?  Fortunately the traffic on the aliases is very
minimal so this 
== is not a concern.

Thanks to everyone who responded.

Doug Otto... You can have up to 255 Ips per worries

Ed Rolison... Virtual hosts (hme0:<xx>) I've not had a problem with.
For quite a while I was running a HTTP/1.0 server which for historical
reasons had 50 or so
separate IP addresses on virtual interfaces.
No real problems with doing this. (I've not done it on qfe, but I see no
reason why this should differ.
The other slight caveat is that outgoing traffic _may_ seem to be coming
from an arbitrary interface
if you have multiple on the same subnet)

Dave McNeill... Adrian Cockroft in 'Sun Performance and Tuning' (Sun
Microsystems Press):
'Up to about 8,000 addresses on a single interface have been tested.'  I
guess this means that another one won't hurt you!

Ozgur C. Demir... You can create 255 instances on one interface unless you
raise the limit
by setting kernel parameter, i dont remember the name of this parameter
but if you need i can find. So, you need to calculate the traffic on each
instance to get the result if you will have a bottleneck or not, it is
completely up to traffic.

Jonathan A. Zdziarski... The default number of aliases is 256.  By setting
ip_addrs_per_if, you
can bring this level up to 8192.  There is no real danger in adding more
interfaces, but if you raise the total number of allowable aliases by
setting ip_addrs_per_if to a higher number, there may be a negative
performance impact on TCP/IP.
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Received on Tue Jan 29 12:23:25 2002

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