| LAN | LANE | LAN switch | LAPB | LAPD | latency | Layer-3 switch | layered architecture | LCP | leaky bucket |
| learning bridge | LE ARP | LEC | LECS | LES | link-state routing algorithm | LLAP | LLC | LMI | LNNI |
| local explorer packet | local loop | LocalTalk | LSA | LUNI | MAC | MAC address | MacIP | MAN | Manchester encoding |
| maximum burst | maximum rate | MBS | MBONE | MCDV | MCLR | MCR | MCTD | MIB | MIP |
| mips | MLP | MMP | modem | modem eliminator | modulation | MOSPF | MPOA | MTU | multicast |
| multicast address | multicast send VCC | multilayer switch | multiplexing |
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