This read-only Integer32 reports the maximum receive reconstructed unit negotiated in the transmit direction for this MLPPP bundle, i.e. the largest reassembled packet size the far end has told this device it can accept. An admin checks this to confirm the negotiated MRRU matches expectations when troubleshooting large-packet issues over the bundle. A TxMRRU smaller than expected could explain why larger packets are being fragmented more aggressively than anticipated toward the peer.