It would mean a reunion with striker Britt Assombalonga who scored 33 goals in his one full season with Posh in 2013-14 before moving to Nottingham Forest for a then club record fee of £5.5 million.
He moved to MIddlesbrough for £15 million in July, 2017.
Forest are now fifth in the Championship and they visited the Bridge last season in the Carabao Cup, with the Blues winning 5-1.
Millwall have been drawn at home again in a cup competition.
Marcelo Bielsa will get his first taste of the FA Cup Cup with Leeds, 20, and Daniel Farke's second-tier leaders Norwich, 28, will be hoping to transform their superb league form over into the cup.
Bradford have followed Posh's lead by heavily reducing prices for the replay.
The draw for the third round of the FA Cup has been conducted this evening and the likes of Arsenal, Liverpool, Tottenham, Chelsea, Man Utd and Man City have discovered their fate.
The ties are due to be played on the weekend of January 4-6, with the winners claiming £135,500 after prize money was doubled for this season.