| isl.addr | Source or Destination Address | 6-byte Hardware (MAC) Address | Source or Destination Hardware Address |
| isl.bpdu | BPDU | Boolean | BPDU indicator |
| isl.crc | CRC | Unsigned 32-bit integer | CRC field of encapsulated frame |
| isl.dst | Destination | 6-byte Hardware (MAC) Address | Destination Address |
| isl.dst_route_desc | Destination route descriptor | Unsigned 16-bit integer | Route descriptor to be used for forwarding |
| isl.esize | Esize | Unsigned 8-bit integer | Frame size for frames less than 64 bytes |
| isl.explorer | Explorer | Boolean | Explorer |
| isl.fcs_not_incl | FCS Not Included | Boolean | FCS not included |
| isl.hsa | HSA | Unsigned 24-bit integer | High bits of source address |
| isl.index | Index | Unsigned 16-bit integer | Port index of packet source |
| isl.len | Length | Unsigned 16-bit integer | |
| isl.src | Source | 6-byte Hardware (MAC) Address | Source Hardware Address |
| isl.src_route_desc | Source-route descriptor | Unsigned 16-bit integer | Route descriptor to be used for source learning |
| isl.src_vlan_id | Source VLAN ID | Unsigned 16-bit integer | Source Virtual LAN ID |
| isl.type | Type | Unsigned 8-bit integer | Type |
| isl.user | User | Unsigned 8-bit integer | User-defined bits |
| isl.user_eth | User | Unsigned 8-bit integer | Priority (for Ethernet) |
| isl.vlan_id | VLAN ID | Unsigned 16-bit integer | Virtual LAN ID |