sFlow Phase 2: ifIndex translation platform/vpp changes

[ritvikiscool9]

Changes to platform/vpp:

• rules/vpp.mk — bumped VPP_VERSION (…-0.3 → …-0.4) so the build pulls the locally-patched VPP instead of the prebuilt upstream deb.
• vppbld/patches/series — registered the new patch in the apply list.
• vppbld/patches/0010-sflow-report-linux-ifindex.patch — the actual feature: adds the report-linux-ifindex mode to the VPP sFlow plugin (helper that maps VPP hw_if_index → Linux netdev ifindex via linux-cp, applied to PSAMPLE flow samples and NET_DM drop alerts) plus the new CLI/API to toggle it.

[mssonicbld]

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[mssonicbld]

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[ritvikiscool9]

To verify sFlow, I enabled it on Ethernet0 (VPP port bobm0) on the collector switch, set the sampling rate and send traffic from the other switch. I then captured a sampled packet with VPP packet trace (trace add dpdk-input).

Trace of a sample packet:

dpdk-input        → packet arrives on bobm0 (Ethernet0)
sflow             → sampled here  (SFLOW: sw_if_index 1)
ethernet-input    → normal L2 parse
ip4-input ... ip4-icmp-input ... ip4-punt → tap4096-tx  → delivered to Linux

When sFlow is enabled on a port, VPP adds an sFlow node to that port's ingress path. Every incoming packet passes through this node, and 1 in N packets (sampling rate) are copied. The orignal packet continues forwarding untouched, the copy is exported out-of-band via PSAMPLE -> hsflowd -> UDP:6343 to the sFlow collector.

A full trace for a packet:

                                                                                   
Packet 50                                                                          
                                                                                   
00:37:46:618831: dpdk-input                                                        
  bobm0 rx queue 0                                                                 
  buffer 0x2e316: current data 0, length 98, buffer-pool 0, ref-count 1, trace hand
le 0x1000031                                                                       
                  ext-hdr-valid                                                    
  PKT MBUF: port 0, nb_segs 1, pkt_len 98                                          
    buf_len 2176, data_len 98, ol_flags 0x0, data_off 128, phys_addr 0x3478c600    
    packet_type 0x0 l2_len 0 l3_len 0 outer_l2_len 0 outer_l3_len 0                
    rss 0x0 fdir.hi 0x0 fdir.lo 0x0                                                
  IP4: 22:b0:a3:50:fa:3a -> 22:34:47:51:c0:a8                                      
  ICMP: 10.0.0.1 -> 10.0.0.2                                                       
    tos 0x00, ttl 64, length 84, checksum 0x3e6d dscp CS0 ecn NON_ECN              
    fragment id 0xe839, flags DONT_FRAGMENT                                        
  ICMP echo_request checksum 0x6d24 id 2                                           
00:37:46:618832: sflow                                                             
  SFLOW: sw_if_index 1, next index 0                                               
  src 22:b0:a3:50:fa:3a -> dst 22:34:47:51:c0:a8                                   
00:37:46:618836: ethernet-input                                                    
  IP4: 22:b0:a3:50:fa:3a -> 22:34:47:51:c0:a8                                      
00:37:46:618837: ip4-input                                                         
  ICMP: 10.0.0.1 -> 10.0.0.2                                                       
    tos 0x00, ttl 64, length 84, checksum 0x3e6d dscp CS0 ecn NON_ECN              
    fragment id 0xe839, flags DONT_FRAGMENT                                        
  ICMP echo_request checksum 0x6d24 id 2                                           
00:37:46:618837: ip4-validate                                                      
  IP4-VALIDATE: sw_if_index 1 next 1 src 10.0.0.1 dst 10.0.0.2                     
00:37:46:618837: ip4-lookup                                                        
  fib 0 dpo-idx 10 flow hash: 0x00000000                                           
  ICMP: 10.0.0.1 -> 10.0.0.2                                                       
    tos 0x00, ttl 64, length 84, checksum 0x3e6d dscp CS0 ecn NON_ECN              
    fragment id 0xe839, flags DONT_FRAGMENT                                        
  ICMP echo_request checksum 0x6d24 id 2                                           
00:37:46:618837: ip4-receive                                                       
    fib:0 adj:10 flow:0x00000000                                                   
  ICMP: 10.0.0.1 -> 10.0.0.2                                                       
    tos 0x00, ttl 64, length 84, checksum 0x3e6d dscp CS0 ecn NON_ECN              
    fragment id 0xe839, flags DONT_FRAGMENT                                        
  ICMP echo_request checksum 0x6d24 id 2                                           
00:37:46:618837: ip4-icmp-input                                                    
  ICMP: 10.0.0.1 -> 10.0.0.2                                                       
    tos 0x00, ttl 64, length 84, checksum 0x3e6d dscp CS0 ecn NON_ECN              
    fragment id 0xe839, flags DONT_FRAGMENT                                        
  ICMP echo_request checksum 0x6d24 id 2                                           
00:37:46:618838: ip4-punt-redirect
  via redirect:0
00:37:46:618838: ip4-dvr-dpo
     sw_if_index:4
00:37:46:618838: ip4-dvr-reinject
     sw_if_index:4
00:37:46:618838: tap4096-output
  tap4096 flags 0x0319000d
  IP4: 22:b0:a3:50:fa:3a -> 22:34:47:51:c0:a8
  ICMP: 10.0.0.1 -> 10.0.0.2
    tos 0x00, ttl 64, length 84, checksum 0x3e6d dscp CS0 ecn NON_ECN
    fragment id 0xe839, flags DONT_FRAGMENT
  ICMP echo_request checksum 0x6d24 id 2
00:37:46:618838: tap4096-tx
    buffer 0x2e316: current data 0, length 98, buffer-pool 0, ref-count 1, trace ha
ndle 0x1000031
                    ext-hdr-valid 
                    local ip4 dvr l2-hdr-offset 0 l3-hdr-offset 14 
  ipv4 hdr-sz 34 l2-hdr-offset 0 l3-hdr-offset 14 l4-hdr-offset 34 l4-hdr-sz 0
  IP4: 22:b0:a3:50:fa:3a -> 22:34:47:51:c0:a8
  ICMP: 10.0.0.1 -> 10.0.0.2
    tos 0x00, ttl 64, length 84, checksum 0x3e6d dscp CS0 ecn NON_ECN
    fragment id 0xe839, flags DONT_FRAGMENT
  ICMP echo_request checksum 0x6d24 id 2

[mssonicbld]

/azp run

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