Medium In VPP>=21.01 ping command no longer seems to work with non-neighbor destinations (i.e. destinations which are routed according to the FIB table).
To reproduce, one may use the VPP CLI and the ip command in the Linux.
VPP side:
vpp$ make run
WARNING: STARTUP_CONF not defined or file doesn't exist.
Running with minimal startup config: unix { interactive cli-listen /run/vpp/cli.sock gid 1000 } dpdk { no-pci }
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DBGvpp# create tap
tap0
DBGvpp# set interface state tap0 up
DBGvpp# set interface ip address tap0 192.168.11.1/24
DBGvpp# show int addr
local0 (dn):
tap0 (up):
L3 192.168.11.1/24
DBGvpp# ip route add 192.168.20.0/24 via 192.168.11.2
DBGvpp# show ip fib
ipv4-VRF:0, fib_index:0, flow hash:[src dst sport dport proto ] epoch:0 flags:none locks:[recursive-resolution:1, default-route:1, ]
...
192.168.20.0/24
unicast-ip4-chain
[@0]: dpo-load-balance: [proto:ip4 index:14 buckets:1 uRPF:14 to:[0:0]]
[0] [@12]: dpo-load-balance: [proto:ip4 index:13 buckets:1 uRPF:12 to:[0:0]]
[0] [@3]: arp-ipv4: via 192.168.11.2 tap0
...
Linux side:
linux$ sudo ip addr add 192.168.20.1/24 dev lo
linux$ sudo ip link set tap0 up
linux$ sudo ip addr add 192.168.11.2/24 dev tap0
linux$ ip addr
...
533: tap0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UNKNOWN group default qlen 1000
link/ether 02:fe:b6:7d:7c:b2 brd ff:ff:ff:ff:ff:ff
inet 192.168.11.2/24 scope global tap0
valid_lft forever preferred_lft forever
inet6 fe80::fe:b6ff:fe7d:7cb2/64 scope link
valid_lft forever preferred_lft forever
...
Then try to run ping from VPP:
DBGvpp# ping 192.168.20.1 Failed: no source address for egress interface Failed: no source address for egress interface Failed: no source address for egress interface Failed: no source address for egress interface Failed: no source address for egress interface
In Linux I noticed that only ICMP6 packet arrived, suggesting that ping incorrectly opted for IPv6 instead of IPv4:
linux$ sudo tcpdump -i tap0
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on tap0, link-type EN10MB (Ethernet), capture size 262144 bytes
14:49:09.486242 IP6 mlenco-nuc > ip6-allrouters: ICMP6, router solicitation, length 16
^C
1 packet captured
1 packet received by filter
0 packets dropped by kernel
