Trouble with dialup connections

  • Hi everybody

    I've posted this query in the Microsoft public newsgroups. I didn't get any response there. So, I'm reposting the query here, and hoping for better luck this time around.

    We're using a merge replication setup to coordinate data

    transfer across various distributed databases. The whole

    scheme seems to work fine when we use broadband (DSL)

    connections. However, over a dial-up (phone) line we keep

    experiencing trouble when subscribers try to synchronize

    with the central publisher database.

    We're using subscriber initiated PULL subscriptions. Also,

    the initial snapshot is generated only the first time the

    snapshot agent runs, never after. The "optimize data for

    slow network connections" option is turned ON. We're using

    a "publisher wins" conflict resolution scheme. And, we're

    using SQL 2000/Windows 2000 Server with all the latest

    sevice packs installed. One last point, the replication

    occurs over FTP.

    The subscriptions are created by a client application

    using VB/ActiveX SQL DMO objects.

    All help appreciated

    VJ

  • Once you're connected the only difference should be the speed of the connection. Could be that you're trying to move too much info and SQL times out, or maybe the connection is bad, getting a lot of retries. I'd enable logging on the repl agents and monitor (these can get big in a hurry). You might take another look at your code to make sure you're trapping and logging errors, sometimes a badly placed resume next can hide things from you.

    Andy

    http://www.sqlservercentral.com/columnists/awarren/

  • Thanks Andy

    I've already tried increasing the timeout period. Didn't really help. The interesting part is that the problem occurs the first time synchronization is attempted after the initial snapshot is applied at the subscriber. Subsequent attempts at syncing are problem free.

    Here's the sequense of steps...

    A. Snapshot applied

    B. First sync after snapshot

    C. Subsequent syncs...

    The problem occurs at step 'B'. The data being transferred in steps 'B' & 'C' is of a similar magnitude. Yet, the problem doesn't manifest after step 'B' completes (if it ever does).

    Vivian

  • Does it occur every time? Would be interesting to profile to see exactly what is coming over when it happens.

    Andy

    http://www.sqlservercentral.com/columnists/awarren/

  • Remote machines on dial-up connections cannot automatically resolve the server names.

    If you are using WINS add an entry for the publisher, or if not add an entry into the hosts file ("C:\WINNT\system32\drivers\etc\hosts" in NT/2000). You can test that this works OK by pinging the publisher by name from the subscriber once connected.

    Also make sure that either there is a trust between the remote domains, or that you are using the accounts with the same username and password at either end to access the publication. Make sure that the account used is in the publication access list.

    If you wish to automate the dial-up the Knowledge Base article Q241149, "INF: How to Automate Replication over a Dial-Up Connection" may be of interest.

    -Ed

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