In RHV is there is any communication between ethernet ports in different bridges within same hypervisor?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 6.x
  • Red Hat Enterprise Linux 7.x
  • Red Hat Virtualization

Issue

  • Is there is any communication between ethernet ports in different bridges within the same physical box in hypervisor environment?

Resolution

Short answer: no communication, they are isolated by default in RHEV Hypervisors.

Long answer: since the ethernet ports are in different bridges, there is no communication by default, unless:
1) IP routing was manually enabled and rules that could mix traffic exist - default is disabled (0 = disabled, 1 = enabled)

# cat /proc/sys/net/ipv4/ip_forward
0

2) NAT has some rules that might affect the traffic - default is empty/no rules, as shown below

# iptables -nvL -t nat
Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain POSTROUTING (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination 

3) Some common device connecting the bridges was manually configured - not by default, very unlikely.
Some more exotic configs like a macvlan pair based on common dummy interface might to that.

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