Differential D28559
netgraph/ng_bridge: move MACs via control message Authored by donner on Feb 9 2021, 8:08 PM. Tags None Referenced Files
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Details Use the new control message to move ethernet addresses from a link to This decouples the read-only activity from the modification under a Depend on D28516 Build a looped bridge + mkpeer bridge b link0
+ name b b
+ mkpeer b: tee link1 left
+ connect b link1 link2 right
+ shutdown b.link1
+ rmhook b
+ mkpeer b: eiface link0 ether
+ mkpeer b: eiface link3 ether
+ msg b: setconfig { debugLevel=3 loopTimeout=60 maxStaleness=900 minStableAge=1 }Now we have a bridge where link1 and link2 are directly connected. Sniff on the seondary interface: # ifconfig ngeth1 up # tcpdump -eni ngeth1 & Check state: # ( ngctl msg b: gettable ; ngctl msg b: getstats 0 ; ngctl msg b: getstats 1 ; ngctl msg b: getstats 2 ; ngctl msg b: getstats 3 ) | fgrep -v response
Args: {}
Args: {}
Args: {}
Args: {}
Args: {}Now send a packet to the bridge: # ifconfig ngeth0 up # ifconfig ngeth0 inet 192.168.234.123/28 alias 18:22:15.869790 58:9c:fc:10:ff:93 > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Request who-has 192.168.234.123 tell 192.168.234.123, length 28 Only a single packet was forwarded, despite of the loop. Check the state of the bridge again: # ( ngctl msg b: gettable ; ngctl msg b: getstats 0 ; ngctl msg b: getstats 1 ; ngctl msg b: getstats 2 ; ngctl msg b: getstats 3 ) | fgrep -v response
Args: { numHosts=1 hosts=[ { addr=58:9c:fc:10:ff:93 hook="link0" age=27 staleness=27 } ] }
Args: { recvOctets=42 recvPackets=1 recvBroadcast=1 }
Args: { recvOctets=42 recvPackets=1 recvBroadcast=1 xmitOctets=42 xmitPackets=1 xmitBroadcasts=1 loopDrops=1 loopDetects=1 }
Args: { recvOctets=42 recvPackets=1 recvBroadcast=1 xmitOctets=42 xmitPackets=1 xmitBroadcasts=1 loopDrops=1 loopDetects=1 }
Args: { xmitOctets=42 xmitPackets=1 xmitBroadcasts=1 }Learning MAC still works. # dmesg | tail ngeth0: Ethernet address: 58:9c:fc:10:ff:93 ngeth0: link state changed to UP ngeth1: Ethernet address: 58:9c:fc:10:ff:c3 ngeth1: link state changed to UP ngeth1: promiscuous mode enabled ng_bridge: b: loopback detected on link1 ng_bridge: b: loopback detected on link2 Debug information is still valid in the kernel log. Waiting for expiry if the loop timeout and staleness timeout # ( ngctl msg b: gettable ; ngctl msg b: getstats 0 ; ngctl msg b: getstats 1 ; ngctl msg b: getstats 2 ; ngctl msg b: getstats 3 ) | fgrep -v response
Args: {}
Args: { recvOctets=42 recvPackets=1 recvBroadcast=1 }
Args: { recvOctets=42 recvPackets=1 recvBroadcast=1 xmitOctets=42 xmitPackets=1 xmitBroadcasts=1 loopDrops=1 loopDetects=1 }
Args: { recvOctets=42 recvPackets=1 recvBroadcast=1 xmitOctets=42 xmitPackets=1 xmitBroadcasts=1 loopDrops=1 loopDetects=1 }
Args: { xmitOctets=42 xmitPackets=1 xmitBroadcasts=1 }Bridge is clean now (beside link stats). So bring a new packet in again: # ifconfig ngeth0 inet 192.168.234.123/28 -alias
# ifconfig ngeth0 inet 192.168.234.123/28 alias
18:29:09.820185 58:9c:fc:10:ff:93 > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Request who-has 192.168.234.123 tell 192.168.234.123, length 28
# ( ngctl msg b: gettable ; ngctl msg b: getstats 0 ; ngctl msg b: getstats 1 ; ngctl msg b: getstats 2 ; ngctl msg b: getstats 3 ) | fgrep -v response
Args: { numHosts=1 hosts=[ { addr=58:9c:fc:10:ff:93 hook="link0" age=2 staleness=2 } ] }
Args: { recvOctets=84 recvPackets=2 recvBroadcast=2 }
Args: { recvOctets=84 recvPackets=2 recvBroadcast=2 xmitOctets=84 xmitPackets=2 xmitBroadcasts=2 loopDrops=2 loopDetects=2 }
Args: { recvOctets=84 recvPackets=2 recvBroadcast=2 xmitOctets=84 xmitPackets=2 xmitBroadcasts=2 loopDrops=2 loopDetects=2 }
Args: { xmitOctets=84 xmitPackets=2 xmitBroadcasts=2 }Now we have the second loop detected and avoided. Try once again, while the loop condition still holds. # ifconfig ngeth0 inet 192.168.234.123/28 -alias
# ifconfig ngeth0 inet 192.168.234.123/28 alias
18:29:20.724345 58:9c:fc:10:ff:93 > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: Request who-has 192.168.234.123 tell 192.168.234.123, length 28
# ( ngctl msg b: gettable ; ngctl msg b: getstats 0 ; ngctl msg b: getstats 1 ; ngctl msg b: getstats 2 ; ngctl msg b: getstats 3 ) | fgrep -v response
Args: { numHosts=1 hosts=[ { addr=58:9c:fc:10:ff:93 hook="link0" age=14 staleness=3 } ] }
Args: { recvOctets=126 recvPackets=3 recvBroadcast=3 }
Args: { recvOctets=84 recvPackets=2 recvBroadcast=2 xmitOctets=126 xmitPackets=3 xmitBroadcasts=3 loopDrops=3 loopDetects=2 }
Args: { recvOctets=84 recvPackets=2 recvBroadcast=2 xmitOctets=126 xmitPackets=3 xmitBroadcasts=3 loopDrops=3 loopDetects=2 }
Args: { xmitOctets=126 xmitPackets=3 xmitBroadcasts=3 }Now the packets are dropped without increasing the loopDetect counter (loop is still in place) Once again the kernel output: # dmesg | tail ng_bridge: b: restoring looped back link2 ng_bridge: b: restoring looped back link1 ng_bridge: b: loopback detected on link1 ng_bridge: b: loopback detected on link2
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