Two real iol-xe containers (Cisco CML iol-runner images, real IOS-XE on
the telnet console) against an isolated instance, the real uBridge with
the swappable bridge TAP leg:
* kernel link reports kernel_datapath; anchors exist from node start
and the per-link bridge enslaves exactly the two of them;
* real ICMP crosses the [unix <-> tap] port-bridge relay; delay 100
lands as netem on both anchors with the measured RTT growing >= 150 ms
and returning < 50 ms when cleared;
* suspend admin-downs the anchor and kills the traffic; resume
restores; AF_PACKET capture writes a real pcap;
* link delete/re-create swaps the port leg out and back in with the
ping returning; node stop leaves no gx devices and a start recreates
the whole wiring from the NIO; project delete cleans everything;
* the relay control on a relay-configured instance keeps the link off
the kernel and still pings (anchors may exist idle — the same
semantics as QEMU's and Dynamips' anchors: the server flag decides
attachment, not anchor birth).
Harness: create_iol_router (the appliance's template properties),
docker_images, iol_anchor_name, stage_iol_base_config (the shipped
iol-xe-base.txt copied into the isolated instance's configs dir — the
GNS3_IOL_STARTUP_CONFIG lookup path), boot_wait(straight_prompt=True)
for images that boot from NVRAM straight into the CLI with no 'Press
RETURN' sentinel, and GNS3_E2E_DEBUG=1 to run the isolated instance
with debug logging (the uBridge command stream lands in server.log —
how the ensure-anchor EBUSY was pinned down).
