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Re: Keepalived vrrp problem

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: Keepalived vrrp problem
From: Sal Tepedino <stepedino@xxxxxxxxxxxxxx>
Date: Fri, 16 Feb 2007 09:15:18 -0500
On Fri, 2007-02-16 at 14:04 +0000, Graeme Fowler wrote:
> On 16/02/2007 13:57, Sal Tepedino wrote:
> > Tried that. IPSec auth. Plain auth. No auth. The results are the same,
> > sadly.
> 
> OK...
> 
> ...dumb question: although you can see the traffic using tcpdump on the 
> backup director, is iptables letting it through to userland? If it's 
> getting blocked, then the backup director won't see the adverts from the 
> master, and when it's missed one or two (I forget how many, so it'll be 
> three!) then it elevates status to MASTER.
> 
> That's the most common cause of BACKUP/MASTER toggling, in my experience.

The backup is seeing all of the mcasts (unless I'm reading the tcpdump
log wrong), and I have cleared iptables, so that can't be it. Here's a
snippet of the tcpdump from the backup:

17:42:19.918550 IP 10.1.1.111 > vrrp.mcast.net: AH(spi=0x0a01016f,seq=0xe): 
VRRPv2, Advertisement, vrid 51, prio 150, authtype ah, intvl 1s, length 20
17:42:20.919460 IP 10.1.1.111 > vrrp.mcast.net: AH(spi=0x0a01016f,seq=0xf): 
VRRPv2, Advertisement, vrid 51, prio 150, authtype ah, intvl 1s, length 20
17:42:21.920495 IP 10.1.1.111 > vrrp.mcast.net: AH(spi=0x0a01016f,seq=0x10): 
VRRPv2, Advertisement, vrid 51, prio 150, authtype ah, intvl 1s, length 20
17:42:22.921405 IP 10.1.1.111 > vrrp.mcast.net: AH(spi=0x0a01016f,seq=0x11): 
VRRPv2, Advertisement, vrid 51, prio 150, authtype ah, intvl 1s, length 20
17:42:23.528528 IP 10.1.1.112 > vrrp.mcast.net: AH(spi=0x0a010170,seq=0xf): 
VRRPv2, Advertisement, vrid 51, prio 100, authtype ah, intvl 1s, length 20
17:42:23.528921 IP 10.1.1.111 > vrrp.mcast.net: AH(spi=0x0a01016f,seq=0x11): 
VRRPv2, Advertisement, vrid 51, prio 150, authtype ah, intvl 1s, length 20
17:42:24.529458 IP 10.1.1.111 > vrrp.mcast.net: AH(spi=0x0a01016f,seq=0x12): 
VRRPv2, Advertisement, vrid 51, prio 150, authtype ah, intvl 1s, length 20
17:42:24.530550 IP 10.1.1.112 > vrrp.mcast.net: AH(spi=0x0a010170,seq=0x10): 
VRRPv2, Advertisement, vrid 51, prio 100, authtype ah, intvl 1s, length 20
17:42:24.530710 IP 10.1.1.111 > vrrp.mcast.net: AH(spi=0x0a01016f,seq=0x12): 
VRRPv2, Advertisement, vrid 51, prio 150, authtype ah, intvl 1s, length 20
17:42:25.531370 IP 10.1.1.111 > vrrp.mcast.net: AH(spi=0x0a01016f,seq=0x13): 
VRRPv2, Advertisement, vrid 51, prio 150, authtype ah, intvl 1s, length 20

.111 is the master, .112 is the backup.
You can see that, say, at :22.921405 (and every second before that,
within a few hundreths of a second) the master adverts, but then
at :23.528528 the backup starts adverting as it starts a transition to
master. .111 then immediately re-adverts to try to keep things in check.

I've also tried switching master/backup so that .111 was the backup
and .112 was the master, but the same thing happens in reverse.


> 
> G
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-- 
Sal Tepedino <stepedino@xxxxxxxxxxxxxx>


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