FreeBSD, quagga (BGP) and 2950 VLANs

[Charles Swiger]

On Sep 19, 2005, at 10:02 AM, Daniel Pocock wrote:
> I've been told that FreeBSD performs routing computations in linear  
> time, even with large routing tables (such as from BGP), and that  
> it is therefore superior to Linux for use as a border router.  Is  
> this so, and are there any specific documents I should review about  
> the performance of FreeBSD routing?

I believe FreeBSD uses a radix lookup for the routing table which is O 
(1); I don't know enough about the implementation in Linux to make  
claims about one platform being superior.

> I've discovered that there is the 4.11 release and the 5.4  
> release.  Are there any compelling reasons why I should choose one  
> of these over the other, for my intended application?  The only  
> application I will be running is quagga.

If you are setting up a new system, you should go with 5.4.  4.11 is  
older and thus extremely well-tested by now, and might arguably be a  
bit more reliable, but 5.4 has better support for ACPI and recent  
hardware, as well as a significantly better SMP implementation.

> I'm planning to connect the FreeBSD server to a trunk port on a  
> Cisco 2950 and put each interconnected IP provider into a separate  
> VLAN.  The documentation I've read so far suggests that FreeBSD is  
> happy with VLANs - will this arrangement work and will it have any  
> significant effect on performance?

This ought to work fine, but you might want to make sure your NICs  
supports VLAN_MTU and VLAN_HWTAGGING options to help offload some of  
the work:

bge0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> mtu 1500
         options=1a<TXCSUM,VLAN_MTU,VLAN_HWTAGGING>

"man 4 vlan" has a more complete discussion, including a list of NICs  
which have this kind of hardware support.  The Broadcom bge's and  
Intel's em seem to work well.

-- 
-Chuck