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I need to set up 2 VLANs, but I have this issue even with only one configured (.2) but when I set up the other VLANc (.1) it seems to work ok.

The issue is that ARP doesnt seem to work which sort of hurts all the rest of networking pretty bad. As I looked into it more - I see that a ping to the gateway on the network for instance induces an ARP request (which seems to make sense since the GW isnt already in the table) I see the request go out on the correct VLAN tag in Tcpdump. I further see the response come back from the gateway telling the MAC address, but the arp table stays stuck with a "(incomplete)" in the arp table. I experience the exact same thing with another end point on the same subnet besides the GW.

Im currently just creating the VLAN with ifconfig eth0.2 172.16.110.240 netmask 255.255.255.192

/var # ping 172.16.110.241 PING 172.16.110.241 (172.16.110.241): 56 data bytes

--- 172.16.110.241 ping statistics --- 2 packets transmitted, 0 packets received, 100% packet loss /var # arp Address HWtype HWaddress Flags Mask Iface 172.16.110.241 (incomplete) eth0.2 /var # /var # /var # ifconfig eth0 Link encap:Ethernet HWaddr 00:1A:E7:FF:D5:E5
inet addr:10.255.213.229 Bcast:10.255.255.255 Mask:255.0.0.0 inet6 addr: fe80::21a:e7ff:feff:d5e5/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:30421 errors:0 dropped:0 overruns:0 frame:0 TX packets:2645 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:2956061 (2.8 MiB) TX bytes:1351612 (1.2 MiB)

eth0.2 Link encap:Ethernet HWaddr 00:1A:E7:FF:D5:E5
inet addr:172.16.110.240 Bcast:172.16.110.255 Mask:255.255.255.192 inet6 addr: fe80::21a:e7ff:feff:d5e5/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3369 errors:0 dropped:0 overruns:0 frame:0 TX packets:1563 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:180561 (176.3 KiB) TX bytes:72348 (70.6 KiB)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:784 errors:0 dropped:0 overruns:0 frame:0 TX packets:784 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:274294 (267.8 KiB) TX bytes:274294 (267.8 KiB)

lightman
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  • Ive gone in and manually added an entry for the GW and then networking seems to work fine for a bit and then something changes and it breaks again until I delete and re-add that arp entry. – lightman Sep 29 '22 at 19:16
  • Starting to wonder if there is something special about .1 - I read that I shouldnt be using it as its sometimes reserved for the system - so maybe if I use .2 and .3 they would both be broken. – lightman Sep 29 '22 at 21:33

1 Answers1

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Well - it turns out for me this was a land mine someone left in a configured arptables which was dropping everything which didnt go to one of my several IP addresses.

lightman
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