Re: probs with ecmp on linux

From: Vincent Guffens (guffens@auto.ucl.ac.be)
Date: Tue Jul 23 2002 - 12:36:59 EST


Did you try to send traffic from different sources ? It think that, because of the route cache, multipath only works for
traffic hashing on different value, i.e with different destination ip, source, dev or tos.

Regards,

On Tue, Jul 23, 2002 at 06:21:59PM +0100, Holger.Woehle@arcor.net wrote:
> Hello,
> i have a problem setting up equal cost multipath (ecmp) on one of my routers.
> This is my network:
>
> +------+
> +---+ | | +---+
> | | 192.168.2.0 | B |====| S | 192.168.1.0
> +------+ | S | +------+ /==eth0===| | | W | +------+
> | | | W |192.168.3.0 | |/ +------+ | I | | |
>
> | Host |===| I |=======eth2=| A | | T |====| http |
> | | | T | | |\ +------+ | C | | |
> +------+ | C | +------+ \==eth1===| | | H | +------+
> | H | 192.168.2.4 | C |====| |
> +---+ | | +---+
> +------+
>
> Router A is the one not willing to do what he had been told to do!
>
> IP-Layer:
> network 1:
> 192.168.3.0/24
> Host:
> eth0 192.168.3.2/24 network 192.168.3.0/24
> Router_A:
> eth2 192.168.3.1/24 network 192.168.3.0/24
> eth0 192.168.2.1/30 network 192.168.2.0/30
> eth1 192.168.2.5/30 network 192.168.2.4/30
> Router_B:
> eth0 192.168.2.6/30 network 192.168.2.4/30
> eth1 192.168.1.1/24 network 192.168.1.0/24
> Router_C:
> eth0 192.168.2.2/30 network 192.168.2.0/30
> eth1 192.168.1.2/24 network 192.168.1.0/24
> network 2:
> 192.168.1.0/24
> http:
> eth0 192.168.1.3/24 network 192.168.1.0/24
>
> Router_A:> ifconfig
>
> eth0 Link encap:Ethernet HWaddr 00:30:48:51:12:A6
> inet addr:192.168.2.1 Bcast:192.168.2.3 Mask:255.255.255.252
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:344 errors:0 dropped:0 overruns:0 frame:0
> TX packets:143 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:100
> RX bytes:44594 (43.5 Kb) TX bytes:11270 (11.0 Kb)
> Interrupt:10 Base address:0xd000
>
> eth1 Link encap:Ethernet HWaddr 00:30:48:51:12:A4
> inet addr:192.168.2.5 Bcast:192.168.2.7 Mask:255.255.255.252
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:128 errors:0 dropped:0 overruns:0 frame:0
> TX packets:205 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:100
> RX bytes:8928 (8.7 Kb) TX bytes:16342 (15.9 Kb)
> Interrupt:11 Base address:0xf000
>
> eth2 Link encap:Ethernet HWaddr 00:05:5D:E6:0D:9D
> inet addr:192.168.3.1 Bcast:192.168.3.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:213 errors:0 dropped:0 overruns:0 frame:0
> TX packets:212 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:100
> RX bytes:17120 (16.7 Kb) TX bytes:34306 (33.5 Kb)
> Interrupt:11 Base address:0x9000
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> UP LOOPBACK RUNNING MTU:16436 Metric:1
> RX packets:164 errors:0 dropped:0 overruns:0 frame:0
> TX packets:164 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
> RX bytes:14884 (14.5 Kb) TX bytes:14884 (14.5 Kb)
>
> Router_A: > ip route add default scope global equalize \
> nexthop via 192.168.2.2 dev eth0 weight 1 \
> nexthop via 192.168.2.130 dev eth1 weight 1
>
> Router_A: > ip route show
>
> 192.168.2.0/30 dev eth0 proto kernel scope link src 192.168.2.1
> 192.168.2.4/30 dev eth1 proto kernel scope link src 192.168.2.5
> 192.168.3.0/24 dev eth2 proto kernel scope link src 192.168.3.1
> default equalize
> nexthop via 192.168.2.2 dev eth0 weight 1
> nexthop via 192.168.2.6 dev eth1 weight 1 pervasive
>
> Settings seem to be ok...
> but all traffic from "Host" to "http" gets routed through gateway eth0 ;-(
> There is no balancing!
> What means "pervasive" after nexthop eth1 ?
>
> can someone comment that,please ?
>
> with regards
> Holger
>
>
>
>
> -
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-- 
				Vincent Guffens, CESAME, UCL

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