If you look at "ifconfig" for the non-primary(active) interface, you should see it say "NOARP" That means it won't respond to any arp requests.... Thanks, Tom Callahan TESSCO Technologies Desk: (410)-229-1361 Cell: (443)-506-6216 Email: callahant@xxxxxxxxxx A real engineer only resorts to documentation when the keyboard dents on the forehead get too noticeable. Vincent Aniello wrote: >I am running bonding with connections to two switches in an >active/backup configuration (mode=1) with eth0 the active interface and >eth1 the backup. In this mode both interfaces receive packets, but only >the active interface transmits packets. I am running RedHat Enterprise >Linux 3.0 (kernel version 2.4.21-27.0.2.Elsmp). > >When both eth0 and eth1 are up and I ping from Host C to Host A I get >duplicate ICMP echo replies. I believe this is also causing duplicate >traffic with other types of traffic as well. > >I believe I know why this is happening and I would like to see if anyone >else has any input on this and hopefully a solution that does not >result in losing the redundancy bonding provides. > >My network topology is as follows: > > | | | | > | Firewall | | Firewall | > +-----+----+ +-----+----+ > | | > | | > +----------+ +-----+----+ +-----+----+ >+----------+ > | | T1 | Router A | Ethernet | Router B | T1 | >| > | Router D +---------+ |-----------| +----------+ >Router C | > | | | Active | | Standby | | >| > | | | Gateway | | Gateway | | >| > +----+-----+ +-----+----+ +-----+----+ >+-----+----+ > | 192.168.1.3/24 192.168.1.4/24 >| > | | <-HSRP 192.168.1.1-> | >| > +----+-----+ +-----+----+ +-----+----+ >+-----+----+ > | | | | | | | >| > | Switch D | | Switch A +-----------+ Switch B | | >Switch C | > | | | +-----------+ | | >| > | | | | | | | >| > +----+-----+ +-----+----+ +-----+----+ >+-----+----+ > |eth0 | | >|eth0 > +--------+ | +--------+ | >+--------+ > | Host D | +------+ Host A +------+ | >Host C | > +--------+ eth0 +--------+ eth1 >+--------+ > bond0 > 192.168.1.20/24 > > >According to my theory the path the echo request packets are taking is >as follows: > > Host c -> Switch C -> Router C -> Router B -> Switch B >-+-------------> Host A eth1 > | > +-> Switch A >-> Host A eth0 > >The destination network 192.168.120.0/24 exists on both Router A and >Router B and HSRP is used for failover between them, with Router A >being the primary gateway. > >The destination network is local to Router B and When the echo request >gets to Router B this router has the MAC address for 192.168.1.20 in its >ARP cache, and if it doesn't it requests it. > >Router B sends the Ethernet frame to the MAC address for 192.168.1.20. >The interfaces eth0, eth1, and bond0 have the same MAC address on the >server. Switch B does not have the MAC address in its MAC address table >and floods the ports. In flooding the ports the server receives the >packet on eth1. The packet is also sent through the connection between >Switch B and Switch A and received on eth0 of the server. > >Since the packet is received twice by the server (on eth0 & eth1) two >echo replies are sent along the following path: > > Host A eth0 -> Switch A -> Router A -> Router B -> Router C -> Switch >C -> Host C > >The reply packet is sent to the primary gateway IP address on Router A. >Switch A learns the MAC address of the server, but Switch B does not. > >The switches only learn a MAC address when traffic is received from a >host on the switch port. The interface eth0 is the active bonding >interface all outbound traffic is sent from this interface and therefore >the MAC address is only learned on the switch port that eth0 is >connected to. Switch B never learns the MAC address for the server and >therefore the duplicate packets never stop when pining Host A from Host >C. > >If I ping Host A from Host D I do not receive duplicate packets. The >echo requests are only received once (through eth0) on the server. The >path the packets travel in this setup is: > > Echo Request: Host D -> Switch D -> Router A -> Switch A -> Host A >eth1 > > Echo Reply: Host A eth0 -> Switch A -> Router A -> Router D -> Switch >D -> Host D > >If I shut down one of the bonded (eth0 or eth1) interfaces I stop >receiving duplicate packets. > >Has anyone else experienced this problem and know how to fix it? > >Thanks. > >--Vincent > > > -- redhat-list mailing list unsubscribe mailto:redhat-list-request@xxxxxxxxxx?subject=unsubscribe https://www.redhat.com/mailman/listinfo/redhat-list
