F1000-AK1115(V7) sip视频会议异常

现场同时开启了nat alg h323和nat alg sip，h323业务正常，但sip业务不正常。

防火墙上做了nat。由内发起的报文源为10.129.Y.Y, 目的为2.32.Z.Z，源IP过防火墙被转成2.32.X.X。

interface Vlan-interface1197

 nat outbound 3000 port-preserved

 nat server protocol udp global 2.32.X.X 5060 inside 10.129.Y.Y 5060 rule ServerRule_8

通过在防火墙上debug看 报文上墙后正常转发：

*Dec  5 16:35:57:304 2024 视频专网防火墙 IPFW/7/IPFW_PACKET: 

Receiving, interface = Route-Aggregation28

version = 4, headlen = 20, tos = 16

pktlen = 61, pktid = 13158, offset = 0, ttl = 63, protocol = 17

checksum = 32034, s = 10.129.Y.Y, d = 2.32.Z.Z

channelID = 0, vpn-InstanceIn = 0, vpn-InstanceOut = 0.

VsysID = 1

prompt: Receiving IP packet from interface Route-Aggregation28.

Payload: UDP

  source port = 5060, destination port = 5060

  checksum = 0x5746, length = 41.

*Dec  5 16:35:57:304 2024 视频专网防火墙 IPFW/7/IPFW_INFO: 

MBUF was intercepted! Phase Num is 3(post routing), Service ID is 7(rir), Bitmap is 100000000000000, return 0(0:continue, 1:dropped, 2:consumed, 3:enqueued, 4:relay)! Interface is Route-Aggregation28,……

*Dec  5 16:35:57:304 2024 视频专网防火墙 SESSION/7/TABLE: 

 Tuple5(EVENT): 10.129.Y.Y/5060-->2.32.X.X/5060(UDP(17))

 Session entry was created.

*Dec  5 16:35:57:304 2024 视频专网防火墙 FILTER/7/PACKET: The packet is permitted. ……

看NAT源IP有转换，且应用层也有过ALG转换：

*Dec  5 16:35:57:304 2024 视频专网防火墙 NAT/7/COMMON: 

 PACKET: (Vlan-interface1197-out-config) Protocol: UDP

      10.129.X.X:5060 -    2.32.Z.Z:5060(VPN:    0)(vsys:    1) ------>

    2.32.X.X:21144 -    2.32.Z.Z:5060(VPN:    0)(vsys:    1)

*Dec  5 16:36:01:107 2024 视频专网防火墙 NAT/7/ALG: 

 PACKET: (Vlan-interface1197) ALG payload was translated according to session table(Src):

    10.129.Y.Y/5060(VPN: 0) ---> 2.32.X.X/5060(VPN: 0)

*Dec  5 16:36:01:107 2024 视频专网防火墙 NAT/7/ALG: 

 PACKET: (ifIndex:0) ALG payload was translated according to session table(Dst-by-L3Head):

    2.32.Z.Z/5060(VPN: 0) ---> 2.32.Z.Z/5060(VPN: 0)

看抓包也是正常的：

尝试在防火墙上加上session alg fragment sip后正常。

后续现场询问SIP业务服务器侧确实有分片需求。