Hi Team,
I need some advice on using the LB in OVN as a distributed/decentralized
Load Balancer.
I have a simple infrastructure on a single HV:
1 LR with 3 LS:
172.31.0.0/24 - for LB VIPs
172.31.1.0/24 - for LB Backends
172.31.2.0/24 - for the source client making requests to the LB
The LB is added to the LR, and the LR doesn't have any DGW ports.
Addresses:
LB: 172.31.0.100:200 (tcp)
Client: 172.31.2.4 (vm)
Backend: 172.31.1.4:10880 (vm)
When I tried to request the LB, I observed the following behavior at the
client interface:
16:09:37.771981 IP 172.31.2.4.57820 > 172.31.0.100.200: Flags [S], seq
719162884, win 29200, options [mss 1460,sackOK,TS val 8275435 ecr
0,nop,wscale 7], length 0
16:09:37.775229 IP 172.31.1.4.10880 > 172.31.2.4.57820: Flags [S.], seq
4108291295, ack 719162885, win 28960, options [mss 1460,sackOK,TS val
8332101 ecr 8275435,nop,wscale 7], length 0
16:09:37.776244 IP 172.31.2.4.57820 > 172.31.1.4.10880: Flags [R], seq
719162885, win 0, length 0
The SYNACK is coming from 172.31.1.4:10880, which is the original
backend address, and it hasn't been unDNATed. As expected, the client
sends an RST to the backend because it is waiting for traffic with the
source address 172.31.0.100, the Load Balancer VIP address.
I also observed different, where is zone 31 it's dnat_zone of LR and
zone 52 it's client interface. I guess, it could be a problem:
1st event:
[NEW] tcp 6 120 SYN_SENT src=172.31.2.4 dst=172.31.0.100
sport=57776 dport=200 [UNREPLIED] src=172.31.1.4 dst=172.31.2.4
sport=10880 dport=57776 zone=31
2nd event:
[NEW] tcp 6 120 SYN_SENT src=172.31.2.4 dst=172.31.0.100
sport=57776 dport=200 [UNREPLIED] src=172.31.0.100 dst=172.31.2.4
sport=200 dport=57776 zone=52
So, in my view it should be work from "box" with single HV, but for
distributed LB it should be also work at source client HV, I mean
backend return origin traffic without unDNAT to HV where is located
client and after that check that is traffic as load balancing and make
unDNAT on client HV.
The main question - is it possible to configure a scheme for
decentralized LB based on LR, or is it only possible if an accurate
chassis is set?
--
Best regards,
Evgenii Kovalev
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