[Madlug] odd CentOS5 networking behavior

[Travis Sobeck]

eth0 = 10.1.25.78
eth2 = 192.168.11.200
I am pinging from my PC and all output below is from the server I am pinging to.  Also I check the mac table on SwitchA and it correctly lists the MAC for eth0 and does not contain the MAC for eth2 anywhere

route -n on server
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.1.25.0       0.0.0.0         255.255.255.0   U     0      0        0 eth0
192.168.11.0    0.0.0.0         255.255.255.0   U     0      0        0 eth2
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth2
0.0.0.0         10.1.25.1       0.0.0.0         UG    0      0        0 eth0

ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:15:17:2d:28:d2 brd ff:ff:ff:ff:ff:ff
    inet 192.168.11.200/24 brd 192.168.11.255 scope global eth2
    inet6 fe80::215:17ff:fe2d:28d2/64 scope link
       valid_lft forever preferred_lft forever
3: eth3: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000
    link/ether 00:15:17:2d:28:d3 brd ff:ff:ff:ff:ff:ff
4: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:19:b9:c3:28:e6 brd ff:ff:ff:ff:ff:ff
    inet 10.1.25.78/24 brd 10.1.25.255 scope global eth0
    inet6 fe80::219:b9ff:fec3:28e6/64 scope link
       valid_lft forever preferred_lft forever
5: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000
    link/ether 00:19:b9:c3:28:e8 brd ff:ff:ff:ff:ff:ff
6: sit0: <NOARP> mtu 1480 qdisc noop
    link/sit 0.0.0.0 brd 0.0.0.0

out when I ping 192.168.11.200 from my pc (note tcpdump is on from the interface with IP 10.1.25.78)
#> tcpdump not port 22 -i eth0 and host 192.168.0.99 -n
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
05:09:58.961016 IP 192.168.0.99 > 192.168.11.200: ICMP echo request, id 512, seq 39425, length 40
05:09:58.961205 IP 192.168.11.200 > 192.168.0.99: ICMP echo reply, id 512, seq 39425, length 40

There is no output when I run the same tcpdump on eth2






________________________________
From: Jon Nelson <madlug at jamponi.net>
To: Travis Sobeck <nex916 at yahoo.com>
Cc: madlug <madlug at madisonlinux.org>
Sent: Thursday, February 26, 2009 10:04:17 AM
Subject: Re: [Madlug] odd CentOS5 networking behavior

Please provide a concrete example with IP addresses and the output of

ip addr show
and
/sbin/route -n

Which machine are you on when you ping? Which machine are you
tcpdumping on? You didn't really give sufficient detail here.

-- 
Jon



      
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