Timesten replication with multiple interfaces sharing the same hostname

Question

Hi,
we have in our environment two Sun T2000 nodes, running SunOS 5.10 and hosting a TT server currently in Release 7.0.5.9.0, replicated between each other.
I would like to have some more information on the behavior of the replication w.r.t. network reliability when using two interfaces associated to the same hostname, the one used to define the replication element.
To make an example we have our nodes sharing this common /etc/hosts elements:
151.98.227.5 TBMAS10df2 TBMAS10df2-10 TBMAS10df2-ttrep
151.98.226.5 TBMAS10df2 TBMAS10df2-01 TBMAS10df2-ttrep
151.98.227.4 TBMAS9df1 TBMAS9df1-10 TBMAS9df1-ttrep
151.98.226.4 TBMAS9df1 TBMAS9df1-01 TBMAS9df1-ttrep
with the following element defined for replication:
ALTER REPLICATION REPLSCHEME
ADD ELEMENT HDF_GNP_CDPN_1 TABLE HDF_GNP_CDPN
CHECK CONFLICTS BY ROW TIMESTAMP
COLUMN ConflictResTimeStamp
REPORT TO '/sn/sps/HDF620/datamodel/tt41dataConflict.rpt'
MASTER tt41data ON "TBMAS9df1-ttrep"
SUBSCRIBER tt41data ON "TBMAS10df2-ttrep"
RETURN RECEIPT BY REQUEST
ADD ELEMENT HDF_GNP_CDPN_2 TABLE HDF_GNP_CDPN
CHECK CONFLICTS BY ROW TIMESTAMP
COLUMN ConflictResTimeStamp
REPORT TO '/sn/sps/HDF620/datamodel/tt41dataConflict.rpt'
MASTER tt41data ON "TBMAS10df2-ttrep"
SUBSCRIBER tt41data ON "TBMAS9df1-ttrep"
RETURN RECEIPT BY REQUEST;
On this subject moving from 6.0.x to 7.0.x there has been some changes I would like to better understand.
6.0.x reported in the documentation for Unix systems:
If a host contains multiple network interfaces (with different IP addresses),
TimesTen replication tries to connect to the IP addresses in the same order as
returned by the gethostbyname call. It will try to connect using the first address;
if a connection cannot be established, it tries the remaining addresses in order
until a connection is established.
Now On Solaris I don't know how to let gethostbyname return more than one interface (the documention notes at this point:
If you have multiple network interface cards (NICs), be sure that “multi
on” is specified in the /etc/host.conf file. Otherwise, gethostbyname will not
return multiple addresses).
But I understand this could be valid for Linux based systems not for Solaris.
Now if I properly understand the above, how was the 6.0.x able to realize the first interface in the list (using the same -ttrep hostname) was down and use the other, if gethostbyname was reporting only a single entry ?
Once upgraded to 7.0.x we realized the ADD ROUTE option was added to teach TT how to use different interfaces associated to the same hostname. In our environment we did not include this clause, but still the replication was working fine regardless of which interface we were bringing down.
My both questions in the end lead to the same doubt on which is the algorithm used by TT to reach the replicated node w.r.t. entries in the /etc/hosts.
Looking at the nodes I can see that by default both routes are being used:
TBMAS10df2:/-# netstat -an|grep "151.98.227."
151.98.225.104.45312 151.98.227.4.14000 1049792 0 1049800 0 ESTABLISHED
151.98.227.5.14005 151.98.227.4.47307 1049792 0 1049800 0 ESTABLISHED
151.98.227.5.14005 151.98.227.4.48230 1049792 0 1049800 0 ESTABLISHED
151.98.227.5.46050 151.98.227.4.14005 1049792 0 1049800 0 ESTABLISHED
TBMAS10df2:/-# netstat -an|grep "151.98.226."
151.98.226.5.14000 151.98.226.4.47699 1049792 0 1049800 0 ESTABLISHED
151.98.226.5.14005 151.98.226.4.47308 1049792 0 1049800 0 ESTABLISHED
151.98.226.5.44949 151.98.226.4.14005 1049792 0 1049800 0 ESTABLISHED
Tried to trace with ttTraceMon but once I brought down one of the interfaces did not see any reaction on either node, if you have some info it would be really appreciated !
Cheers,
Mike

Answer 1

Hi Chris,
Thanks for the reply, I have few more queries on this.
1.Using the ROUTE CLAUSE we can use multiple IPs using priority level set, so that if highest priority level set in thr ROUTE clause for the IP is not active it will fall back to the next level priority 2 set IP. But cant we use ROUTE clause to use the multiple route IPs for replication simultaneously?
2. can we execute multiple schema for the same DSN and replication scheme but with different replication route IPs?
for example:
At present on my system, I have a replication scheme running for a specific DSN with stand alone Master-Subscriber mechanism, with a specific route IP through VLAN-xxx for replication.
Now I want to create and start another replication scheme for the same DSN and replication mechanism with a different VLAN-yyy route IP to be used for replication in parallel to the existing replication scheme. without making any changes to the pre-existing replication scheme.
for the above scenarios, will there be any specific changes respective to the different replication schema mechanism ie., Active Standby and Standalone Master Subscriber mechanism etc.,
If so what are the steps. like how we need to change the existing schema?
Thanks In advance.
Naveen