DB Link was very slow and Oracle Errors

Dear Oracle Experts,

One new DB just created on Oracle11g (11.1.0.7.0) on 64bit Windows 2008R1

I created a DB link on the new DB with a source DB (Oracle9i ,version9.2.0.8, on 32bit Windows 2003).

The DB link was working, but slowly. Even I used select statement and description a table on source DB.

When a big data select from source DB and insert into target DB, I got errors,

ORA-01555: snapshot too old: rollback segment number  with name "" too small
ORA-06512: at "MPSS.USR_INITIATE", line 35
ORA-06512: at line 1
01555. 00000 -  "snapshot too old: rollback segment number %s with name \"%s\" too small"