I am just not "getting" this whole Linux networking thing.
I am using RH6.[0,1,2] mostly, and solely the 2.2 kernels.
I have x86 class machines with dual NICs (Intel EtherExpress).
The NICs are in two separate VLANs. Also, I tried the Linux
boxes with three NICs and could get absolutely no connectivity
no matter what I tried so I am back to dual NICs now.
My network consists of multiple VLANs created by two Catalyst
6500s in Layer 2 mode with IEEE Spanning Tree (except using
Cisco's Per-VLAN STP model). I have ISL trunks configured between
them and to a 3500XL. All are in the same VTP domain, and I am
using pruning to limit the VLAN exchange information. I am not
using portfast, or any other obscure Cisco setting. Does Linux
work well in this type of environment, or should I change to
I am having some strange networking problems with these Linux boxes.
They are not forwarding/routing IP in any way (as set by myself),
but the routing tables are often different on these boxes. Sometimes
when I reboot them or down the interfaces and bring them back up, I see
strange things happen.
First off, I see the routing tables change, they are never the same.
I cannot make all the servers maintain the same routing table. This
should be something I can statically set and maintain, but it does not
seem that way after many hours of playing with it.
Sometimes the routing tables with show the interfaces' IP addresses, and
sometimes not. I have used the 'ip route' command to verify my 'netstat -rn'
settings and sometimes they don't even match.
The most bothersome thing is displaying the ARP cache. When using 'arp -an',
sometimes it gets the wrong MAC addresses off of a different interface.
And the worst part is, that I can find no setting for ARP cache timeouts,
or what not. I found gc_timeout, but I believe that is routing related.
E.g. When I ping a broadcast addr to find all of the ips attached to the
network, I then list the arp table, finding no entries. Then, 15 seconds
later I list the arp table and they are all there. Finally, in another
15 seconds they are all gone. How am I supposed to troubleshoot any
networking problems under Linux when the arp cache and routing tables
are constantly changing?
Also, what is this business with route -net? Why doesn't route just
know that 10.0.1.0 is a network and not a host? Why can't I sometimes
add a -net or -host? Actually, I've never had -host even work.
After reading everything I could on linux.com, linuxdoc.org, linuxports.com,
kernel.org, linuxhq.com, and redhat.com -- nothing talks about this. The
Net3/4/Networking HOWTO is very poorly written, it does not identify or
discuss any of these problems. I even started reading usenet and mailing
lists to look for this information. It is not available. Please advise.
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