The XPAK ports are numbered 20–23 (Figure 3). Each XPAK port is served by an XPAK optical transceiver or an XPAK switch stacking cable. An XPAK port is capable of 10 Gb/s (actual data transmission bandwidth 12.75 Gb/s) or 20 Gb/s (actual data transmission bandwidth 25.5 Gb/s) with the optional license key. XPAK ports are hot-pluggable and can self-discover transmission speed when connected to other switches. The XPAK switch stacking cable is a passive cable and transceiver assembly for connecting to other XPAK-capable switches. The XPAK ports come with covers that must be removed before installing transceivers or cables. XPAK port LEDs are located to the left of their respective ports and provide port login and activity status