On 16-01-25 03:43 PM, rizz2pro . wrote: > Ok we've figured it out. > > We have a couple identical environments all attached to one switch and > they are all advertising the same VHIDs to each other and it looks to > be causing some arp problems. (Environment A was getting CARP > advertisements from Environment B and vice versa) > > After specifying a "carppeer" on each CARP interface attached to that > switch in all 3 environments the issue went away. All 3 environments > are using the same VHID. > > Thanks for the help
Umm... per http://www.openbsd.org/faq/pf/carp.html > /vhid/ > The Virtual Host ID. This is a unique number that is used to > identify the redundancy group to other nodes in the group, and to > distinguish between groups on the same network. Acceptable values > are from 1 to 255. This must be the same on all members of the group. Note the word "unique". Basically, by having multiple clusters with the same VHID, you deliberately broke carp(4). VRRP would have broken in exactly the same way, and I think HSRP would also have broken in same way, too. However, I see that neither carp(4) nor ifconfig (8) indicates that VHID should be unique and not shared, except by very weak implication. If specifying a common VHID is not only contraindicated, but causes actual breakage on the network (as seen here), then the manpage(s) should say so, IMO. (IIRC, the manpages are canonical, not the FAQ...?) Drat, I don't have a copy of -current on this system... following is a proposed diff against 5.8-RELEASE. Sorry for not doing a proper diff against -current but if I wait, I'll forget. At least this way I might remember later. I know in VRRP, the VHID is used to generate the MAC address, but I don't recall if carp(4) works the same way. If it does, then the language I suggest for carp(4) below may be too permissive, in that use of carppeer will stop each system from complaining, but external clients will still encounter difficulties with ARP. -Adam --- carp.4.dist 2016-01-25 18:04:39.152065865 -0600 +++ carp.4 2016-01-25 18:08:14.326975564 -0600 @@ -58,6 +58,10 @@ a common virtual host ID (VHID) and virtual host IP address on each machine which is to take part in the virtual group. +The VHID uniquely identifies a cluster locally within a broadcast domain +(network segment), but may be reused on other networks. The +.Cm carppeer +option may also be used avoid conflicting VHID multicasts. Additional parameters can also be set on a per-interface basis: .Cm advbase and --- ifconfig.8.dist 2016-01-25 18:15:07.089080002 -0600 +++ ifconfig.8 2016-01-25 18:14:35.745168361 -0600 @@ -849,6 +849,7 @@ Set the virtual host ID to .Ar n . Acceptable values are 1 to 255. +Clusters on the same network should use unique IDs. .El .Pp Taken together, the
