It depends on your level of retention and current understanding. I can tell you, in general, the Wireshark cert will drill a LOT into you, and I'm not sure that I'd say CCNA is as 'involved' as the Wireshark cert. CCNA is, in general, vendor-specific (while some topics, such as subnetting and general understanding of VLAN's, for instance, carryover to other vendors' stuff,) whereas, Wireshark will ALWAYS apply, regardless of your network provider or hardware, and goes deeper into understanding, at the packet level.
If it were me, and I had to spend my money, I'd do Wireshark. But if you want / need both, and are learning, I'd do CCNA first, to make sure you understand at least the basics of such topics, as I'd listed, above, then go Wireshark. (Unless you already solidly understand TCP/IP and how it works.)
~ hayabusa ~
"All men can see these tactics whereby I conquer, but what none can see is the strategy out of which victory is evolved." - Sun Tzu, 'The Art of War'
OSCE, OSCP , GPEN, C|EH