The arista-sll-interface-any.pcap file contains a pcap of the router control plane traffic on veos. it was captured using the -i any parameter to tcpdump, which causes each packet to be encapsualted in an SLL header (see https://github.com/the-tcpdump-group/libpcap/blob/master/pcap/sll.h)
Bytes 14 and 15 of this SLL header contain either an ethertype, a value from 1-4 or some other arbitrary numbers. type 4 indicates and LLC header.