Proof using name_map_bijective.
move => f h d.
apply functional_extensionality => n.
rewrite /update /=.
case (name_eq_dec _ _) => H_dec; case (name_eq_dec _ _) => H_dec' //.
- rewrite -H_dec in H_dec'.
by rewrite H_dec.
- case: H_dec'.
rewrite -H_dec.
by rewrite tot_map_name_inverse_inv.
- rewrite H_dec' in H_dec.
by rewrite tot_map_name_inv_inverse in H_dec.
Qed.

Lemma pt_ext_map_update_eq_some :
forall net d p p',
pt_map_packet p = Some p' ->
(fun n : name => pt_ext_map_data (update name_eq_dec (nwState net) (pDst p) d (tot_map_name_inv n)) (tot_map_name_inv n)) =
update name_eq_dec (fun n : name => pt_ext_map_data (nwState net (tot_map_name_inv n)) (tot_map_name_inv n)) (pDst p') (pt_ext_map_data d (pDst p)).