Re: Equal Cost Multipath?

Brian Anderson (bunicula@mediaone.net)
Thu, 2 Sep 1999 08:06:26 -0400 (EDT)


On Wed, 1 Sep 1999, Matthew G. Marsh wrote:

> Let me know what you end up seeing. Thanks!

Quick review for anyone not reading earlier messages: I have a home lan,
with 10 machines, IPMASQing out to the internet over a cable modem. Last
night, I installed a third NIC and a second cable modem. I'm now trying
to see what I can get to happen with load sharing.

The 3rd interface went in without a hitch, both connections wer up, and it
was looking good.

First thing I learned was that anyone trying this should really prepare
their firewall/ipchains script in advance. Suddenly I was presented with
things like:

ipchains -A output -i eth0 -s 0.0.0.0 -j ACCEPT

about a hundred times. and of course, that needed to be adjusted so that
it would apply to both interfaces. eventually it became

for INT in eth0 eth2
do
/sbin/ipchains -A output -i $INT -s 0.0.0.0 -j ACCEPT
done

much better thing. the firewall script had been kicking around since
2.1.90 or so, and really needed a rewrite. i hadn't planned for multiple
external interfaces at home :)

But other than that hurdle, things are working, to an extent. I can really
tell where outgoing traffic is going. Any thoughts on how to monitor which
interface is being used? I thought traceroute would work, but both
interfaces have the same next hop router...

ifconfig shows traffic on both interfaces:

eth0 RX packets:59248 errors:0 dropped:0 overruns:0 frame:0
TX packets:969 errors:0 dropped:0 overruns:0 carrier:0

eth2 RX packets:42185 errors:0 dropped:0 overruns:0 frame:0
TX packets:16295 errors:0 dropped:0 overruns:0 carrier:0

eth0 hasn't transmitted much...

the routing table is (editted for privacy and screen width):

Destination Gateway Iface
192.168.2.1 * eth1
192.168.2.0 * eth1
24.x.x.0 * eth0
24.x.x.0 * eth2
127.0.0.0 * lo
default 24.x.x.1 eth2
default 24.x.x.1 eth0

Current kernel networking options:

CONFIG_PACKET=y
CONFIG_NETLINK=y
CONFIG_RTNETLINK=y
CONFIG_NETLINK_DEV=y
CONFIG_FIREWALL=y
CONFIG_UNIX=y
CONFIG_INET=y
CONFIG_IP_ADVANCED_ROUTER=y
CONFIG_RTNETLINK=y
CONFIG_NETLINK=y
CONFIG_IP_MULTIPLE_TABLES=y
CONFIG_IP_ROUTE_MULTIPATH=y
CONFIG_IP_ROUTE_TOS=y
CONFIG_IP_ROUTE_NAT=y
CONFIG_IP_FIREWALL=y
CONFIG_IP_FIREWALL_NETLINK=y
CONFIG_NETLINK_DEV=y
CONFIG_IP_ALWAYS_DEFRAG=y
CONFIG_IP_TRANSPARENT_PROXY=y
CONFIG_IP_MASQUERADE=y
CONFIG_IP_MASQUERADE_ICMP=y
CONFIG_IP_MASQUERADE_MOD=y
CONFIG_IP_MASQUERADE_IPAUTOFW=y
CONFIG_IP_MASQUERADE_IPPORTFW=y
CONFIG_IP_MASQUERADE_MFW=y
CONFIG_IP_ROUTER=y
CONFIG_NET_IPIP=y
CONFIG_NET_IPGRE=y
CONFIG_IP_ALIAS=y
CONFIG_SYN_COOKIES=y
CONFIG_SKB_LARGE=y
CONFIG_ATALK=y

So then, any suggestions on how to test this setup out, and see just how
much we can get out of it?

brian

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