In VPC A, routes to 10.0.0.0/8 are directed to the Transit Gateway
[ec2-user@ip-192-168-0-40 ~]$ traceroute 10.99.99.99
traceroute to 10.99.99.99 (10.99.99.99), 30 hops max, 60 byte packets
1 * * *
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 * * *
8 * * *
9 * * *
10 * * *
11 * * *
12 * * *
13 * * *
14 * * *
15 * * *
16 * * *
17 * * *
18 * * *
19 * * *
20 * * *
21 * * *
22 * * *
23 * * *
24 * * *
25 * * *
26 * * *
27 * * *
28 * * *
29 * * *
30 * * *
In VPC B, where routes to 10.0.0.0/8 are sent
[ec2-user@ip-192-168-128-105 ~]$ sudo tcpdump -i eth0 src host 192.168.0.40
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
09:19:30.781115 IP 192.168.0.40.38311 > 10.99.99.99.33440: UDP, length 32
09:19:30.781129 IP 192.168.0.40.54693 > 10.99.99.99.33438: UDP, length 32
09:19:30.781149 IP 192.168.0.40.59916 > 10.99.99.99.33441: UDP, length 32
09:19:30.781218 IP 192.168.0.40.57387 > 10.99.99.99.33437: UDP, length 32
09:19:30.781221 IP 192.168.0.40.52615 > 10.99.99.99.33439: UDP, length 32
09:19:30.781502 IP 192.168.0.40.34492 > 10.99.99.99.33443: UDP, length 32
09:19:30.781506 IP 192.168.0.40.38332 > 10.99.99.99.33442: UDP, length 32
09:19:30.781507 IP 192.168.0.40.35326 > 10.99.99.99.33444: UDP, length 32
09:19:30.781509 IP 192.168.0.40.44051 > 10.99.99.99.33445: UDP, length 32
09:19:30.781510 IP 192.168.0.40.55744 > 10.99.99.99.33446: UDP, length 32
09:19:30.781512 IP 192.168.0.40.40774 > 10.99.99.99.33448: UDP, length 32
09:19:30.781513 IP 192.168.0.40.39172 > 10.99.99.99.33447: UDP, length 32
09:19:30.781808 IP 192.168.0.40.54484 > 10.99.99.99.33449: UDP, length 32
09:19:35.788060 IP 192.168.0.40.59689 > 10.99.99.99.33451: UDP, length 32
09:19:35.788142 IP 192.168.0.40.57552 > 10.99.99.99.33450: UDP, length 32
09:19:35.788179 IP 192.168.0.40.53264 > 10.99.99.99.33452: UDP, length 32
09:19:35.788222 IP 192.168.0.40.39280 > 10.99.99.99.33462: UDP, length 32
09:19:35.788303 IP 192.168.0.40.51369 > 10.99.99.99.33455: UDP, length 32
09:19:35.788306 IP 192.168.0.40.53104 > 10.99.99.99.33456: UDP, length 32
09:19:35.788430 IP 192.168.0.40.60540 > 10.99.99.99.33461: UDP, length 32
09:19:35.788555 IP 192.168.0.40.51091 > 10.99.99.99.33453: UDP, length 32
09:19:35.788559 IP 192.168.0.40.52623 > 10.99.99.99.33454: UDP, length 32
09:19:35.788561 IP 192.168.0.40.46468 > 10.99.99.99.33463: UDP, length 32
09:19:35.788645 IP 192.168.0.40.51467 > 10.99.99.99.33457: UDP, length 32
09:19:35.788650 IP 192.168.0.40.43052 > 10.99.99.99.33459: UDP, length 32
09:19:35.788652 IP 192.168.0.40.54315 > 10.99.99.99.33460: UDP, length 32
09:19:35.788761 IP 192.168.0.40.56382 > 10.99.99.99.33458: UDP, length 32
09:19:35.788887 IP 192.168.0.40.40745 > 10.99.99.99.33464: UDP, length 32
09:19:35.788891 IP 192.168.0.40.36916 > 10.99.99.99.33465: UDP, length 32