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Check 1+1 SP Comms

Apr 2021

Introduction

The 1+1 SPs communicate with each other over the Management network using various ports, these are:

15771 for Mux comms

15772 for Simulcrypt

15778 for stat Mux

We can use tcpdump to monitor the traffic between the Muxes by specifying the relevant port.

  tcpdump -i mngt port 15778 -Q out

This will show Stat Mux traffic (as in the stat mux control messages).

The active Mux will show something like below:

tcpdump -i eth0 port 15778 -Q out

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
15:49:22.309719 IP sp01.15778 > 235.2.127.254.15778: UDP, length 61
15:49:22.851978 IP sp01.15778 > 235.2.127.254.15778: UDP, length 61
15:49:23.394021 IP sp01.15778 > 235.2.127.254.15778: UDP, length 61
15:49:23.936007 IP sp01.15778 > 235.2.127.254.15778: UDP, length 61
15:49:24.478037 IP sp01.15778 > 235.2.127.254.15778: UDP, length 61
15:49:25.019993 IP sp01.15778 > 235.2.127.254.15778: UDP, length 61
15:49:25.562039 IP sp01.15778 > 235.2.127.254.15778: UDP, length 61
15:49:26.104193 IP sp01.15778 > 235.2.127.254.15778: UDP, length 61
15:49:26.646276 IP sp01.15778 > 235.2.127.254.15778: UDP, length 61
15:49:27.188263 IP sp01.15778 > 235.2.127.254.15778: UDP, length 61

Where as the inactive mux will have no tcpdump output

tcpdump -i eth0 port 15778 -Q out

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes

If we look at the Mux Comms on 15771 then we see activity from BOTH Muxes:

On the Main Mux

tcpdump -i eth0 port 15771 -Q out

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
15:58:10.290160 IP sp01.15771 > 235.2.127.254.15771: UDP, length 207
15:58:10.790638 IP sp01.15771 > 235.2.127.254.15771: UDP, length 207
15:58:11.290752 IP sp01.15771 > 235.2.127.254.15771: UDP, length 207
15:58:11.791356 IP sp01.15771 > 235.2.127.254.15771: UDP, length 207
15:58:12.291375 IP sp01.15771 > 235.2.127.254.15771: UDP, length 207
15:58:12.791417 IP sp01.15771 > 235.2.127.254.15771: UDP, length 207
15:58:13.291816 IP sp01.15771 > 235.2.127.254.15771: UDP, length 207
15:58:13.792613 IP sp01.15771 > 235.2.127.254.15771: UDP, length 207
15:58:14.293486 IP sp01.15771 > 235.2.127.254.15771: UDP, length 207
15:58:14.793887 IP sp01.15771 > 235.2.127.254.15771: UDP, length 207

On the Backup Mux

tcpdump -i eth0 port 15771 -Q out

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
15:58:10.255915 IP sp02.15771 > 235.2.127.254.15771: UDP, length 209
15:58:10.756223 IP sp02.15771 > 235.2.127.254.15771: UDP, length 209
15:58:11.256603 IP sp02.15771 > 235.2.127.254.15771: UDP, length 209
15:58:11.756856 IP sp02.15771 > 235.2.127.254.15771: UDP, length 209
15:58:12.257007 IP sp02.15771 > 235.2.127.254.15771: UDP, length 209
15:58:12.757740 IP sp02.15771 > 235.2.127.254.15771: UDP, length 209
15:58:13.258254 IP sp02.15771 > 235.2.127.254.15771: UDP, length 209
15:58:13.758822 IP sp02.15771 > 235.2.127.254.15771: UDP, length 209
15:58:14.259383 IP sp02.15771 > 235.2.127.254.15771: UDP, length 209
15:58:14.760368 IP sp02.15771 > 235.2.127.254.15771: UDP, length 209