mpcd(8)

🎀 mpcd(8) — Maintenance Commands, but make it a group chat 🎀

okay bestie, sit down, hydrate, because we're talking about mpcd — the ATM MPOA (Multi-Protocol Over ATM) client daemon. yes it's giving 1998, yes it's iconic, yes we're gonna understand every single byte of it together. 💖

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✨ SYNOPSIS ✨

mpcd [ -s Control ATM address ] [ -l Data ATM address ] [ -c MPS control
ATM address ] [ -i Interface number ] [ -m MPS MAC address ] [ -L LEC
address [ -n ELAN name ] [ -C LECS Address ]]

not the nested brackets giving me trust issues but okay, we move.

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🌸 DESCRIPTION 🌸

So. The MPOA client — aka MPC — is the girl whose whole job is creating and receiving internetwork layer shortcuts. Using these shortcuts, MPCs forward unicast internetwork layer packets effectively over ATM without needing routing protocols. no routing protocols. none. we simply don't need them. 💅

MPC has two roles, and she's serving both:

• ingress — here MPC detects flows destined outside its own subnet and tries to establish shortcuts to those destinations.
• egress — here MPC accepts shortcuts and packets arriving on those shortcuts.

Maintaining shortcuts? That's a team effort, done with the help of the MPOA server (MPS). bestie support system fr fr 🫶

Just like the Linux LAN Emulation client, the MPOA client is also divided in two parts:

1. the kernel component
2. the daemon process

The daemon opens and receives data shortcuts and control connections with the kernel component. The kernel component tallies packets flowing out from the LANE device and makes the decision on whether a packet should be forwarded using LANE or MPOA shortcuts. she's the main character making the calls. 👑

heads up: if the daemon is killed with SIGHUP it will close all the open connections, purge ingress and egress cache entries, query LECS if applicable, and then restart itself. it's giving "not me ghosting then coming back like nothing happened" 😭

Linux MPOA client only supports non-LLC-muxed shortcuts. But the number of supported MPOA clients is unlimited ✨. unlimited clients. we love scalability.

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💅 OPTIONS 💅

• -s Control ATM address — Local ATM address this MPC uses for MPOA control connections. it's her control-connection address, periodt.
• -l Data ATM address — Local ATM address from and to which MPOA shortcuts are established. the data address, the whole vibe of the shortcuts.
• -c MPS control ATM address — ATM address of MPS. Only needed if MPS can not advertise it by itself. so like, only when MPS is being shy 🙈.
• -i Interface number — The interface number of the LEC this MPC serves. E.g. 2 for "lec2". yes literally just the number. so if it's lec2, you pass 2. no cap.
• -m MPS MAC address — MAC address of default router where MPS recides. Only useful if the MPOA server fails to advertise itself. (and yes, "recides" is a typo in the original and I am keeping it because it's iconic and I don't make the rules 💀)
• -L LEC address — Listen address of the LANE client zeppelin. mpcd uses this address as its own ATM address when it queries LECS for MPC configuration parameters. If this option is not present, then mpcd will not use LECS to query for configuration parameters. This option is normally the same as zeppelin's -l option.
• -n ELAN name — Name of the ELAN for which mpcd asks for parameters when it connects to LECS. If this option is not given, LECS should respond with parameters belonging to the default ELAN if one exists. This option is normally the same as zeppelin's -n option.
• -C LECS address — ATM address of LECS mpcd asks for parameters. If this option is left empty and -L is given, mpcd uses the ATM Forum assigned Well-Known LECS address. This option is normally the same as zeppelin's -c option.

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🌈 EXAMPLES 🌈

This script snippet shows how to run LANE and MPOA. After UNI signalling and ILMI have been started, LANE (zeppelin) and MPOA (mpcd) are started. The commented out line shows how to start mpcd so that it queries LECS for MPC parameters. 🦋

Arguments jaarli[1-3] are local ATM addresses listed in file /etc/hosts.atm. yes bestie, /etc/hosts.atm. 💖

ATM=/usr/src/atm
case "$1" in
start)
    cd $ATM
    if [ -x sigd/atmsigd ] ; then
               sigd/atmsigd -b
    fi
    if [ -x ilmid/ilmid ] ; then
               ilmid/ilmid -b -x
    fi
    if [ -x led/zeppelin ] ; then
               led/zeppelin -2 -n sampo -i2 -l jaarli3 &
               ifconfig lec2 10.10.10.208 \
                           netmask 255.255.255.192 \
                           broadcast 10.10.10.255
               ifconfig lec2 up
               route add default gw 10.10.10.193
    fi
    if [ -x mpoad/mpcd ] ; then
               mpoad/mpcd -i2 -s jaarli1 -l jaarli2 &
               #mpoad/mpcd -i2 -s jaarli1 -l jaarli2 \
                           -L jaarli3 -n sampo &
    fi
    ;;
esac
exit 0

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💀 BUGS 💀

Supports only Ethernet type of ELANs. Probably others too. (that's it. that's the bug report. she said "probably." and left. 🙈)

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🫶 AUTHORS 🫶

Heikki Vatiainen <hessu@cs.tut.fi>, Sampo Saaristo <s156953@cs.tut.fi>

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🔥 SEE ALSO 🔥

• zeppelin(8)
• atmsigd(8)

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and that's the whole page bestie, you ate that, no crumbs. 🧚 this one's from the Linux crew, dated Nov 17, 1998 — yes, a 1998 girlie still serving ATM networking realness, and honestly? iconic. go forth and shortcut. ⭐💜