learning vpp:dhcp relay功能（2）

dpdk-vpp源码解读

发布于 2024-11-23 08:30:55

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代码可运行

在上一篇中，我们介绍了 DHCP Relay 的一些基本概念及 VPP DHCP Relay 的实现方法。最初在搭建测试环境时，我们使用了 dnsmasq 作为 DHCP 服务器，测试一切正常。然而，在客户环境中，客户端无法分配到 IP 地址。客户环境中使用的是 Windows Server 2012 版本搭建的 DHCP 服务器。促使我必须深入研究dhcp中继代理实现逻辑及查阅各个dhcp服务器处理逻辑。

为了复现客户环境，我在 VM 虚拟机中安装了 Windows Server 2012 镜像，并部署了 DHCP 服务器。将DHCP 服务器与VPP其中一个接口设置在同一个网段互联，这样可以使用dhcp relay功能了。关于如何在 Windows Server 2012 上部署 DHCP 服务器，网上有很多教程，也可以参考这些教程进行部署。如果需要，也可以使用 Windows Server 2016 进行搭建，步骤类似。

在 VPP 命令行中添加 DHCP 中继服务器地址时，同一个 VRF 下只能指定一个 src-address，但可以配置多个 DHCP 服务器地址。当 DHCP Relay 服务器收到 DHCP DISCOVER 报文后，会将其转换为单播报文，并在 Option 选项中追加 Option 82 的 Sub-option 1 和 Sub-option 5。然后，DHCP Relay 服务器会为每个配置的 DHCP 服务器地址复制一份报文并发送出去。

set dhcp proxy [del] server <ip-addr> src-address <ip-addr> [server-fib-id <n>] [rx-fib-id <n>]

在DHCP 中继代理逻辑中新增了两个node节点，一是dhcp-proxy-to-client 主要处理dhcp 服务器回应给DHCP中继agent的dhcp报文，经过处理之后转发给DHCP 请求终端。另外一个是dhcp-proxy-to-server节点主要是接收到DHCP请求终端发送给DHCP中继agent的dhcp报文，转换成单播报文发送给DHCP server服务器。

这里有疑问报文如何被送两个节点的？通过注册UDP 端口号 67和68，当中继代理服务器收到报文目的端口是68时，表示报文是dhcp 服务器回应的DHCP报文需送到节点dhcp-proxy-to-client 去处理。当中继服务器收到报文的目的端口是67时，表示终端发送给DHCP服务器的报文需送到dhcp-proxy-to-server节点去处理。默认情况下DHCP DISCOVE和DHCP request都是广播报文，目的IP是255.255.255.255，这样就需要设置255.255.255.255路由为local路由，这样就可以送到ip4-udp-loopup节点去解析端口号，将报文送到端口号对应的node节点。在配置前dhcp 中继代理配置命令行前，我们查询了查询路由255.255.255.255 forwarding状态是drop。如下：

dpdk-vpp源码分析: show ip fib 255.255.255.255
ipv4-VRF:0, fib_index:0, flow hash:[src dst sport dport proto flowlabel ] epoch:0 flags:none locks:[adjacency:1, default-route:1, ]
255.255.255.255/32 fib:0 index:4 locks:2
  default-route refs:1 entry-flags:drop, src-flags:added,contributing,active,
    path-list:[4] locks:2 flags:drop, uPRF-list:4 len:0 itfs:[]
      path:[4] pl-index:4 ip4 weight=1 pref=0 special:  cfg-flags:drop,
        [@0]: dpo-drop ip4

 forwarding:   unicast-ip4-chain
  [@0]: dpo-load-balance: [proto:ip4 index:5 buckets:1 uRPF:4 to:[0:0]]
    [0] [@0]: dpo-drop ip4

当我们配置完DHCP 中继代理配置之后，再此查询255.255.255.255路由指向了本地local0路由如下：

dpdk-vpp源码分析: set dhcp proxy server 192.168.1.1 src-address 192.168.10.1
dpdk-vpp源码分析: show ip fib 255.255.255.255
ipv4-VRF:0, fib_index:0, flow hash:[src dst sport dport proto flowlabel ] epoch:0 flags:none locks:[DHCP:2, adjacency:1, default-route:1, ]
255.255.255.255/32 fib:0 index:4 locks:3
  DHCP refs:1 entry-flags:local, src-flags:added,contributing,active,
    path-list:[19] locks:2 flags:local, uPRF-list:14 len:0 itfs:[]
      path:[21] pl-index:19 ip4 weight=1 pref=0 receive:  oper-flags:resolved, cfg-flags:local,
        [@0]: dpo-receive: 0.0.0.0 on local0

  default-route refs:1 entry-flags:drop, src-flags:added,
    path-list:[4] locks:1 flags:drop, uPRF-list:4 len:0 itfs:[]
      path:[4] pl-index:4 ip4 weight=1 pref=0 special:  cfg-flags:drop,
        [@0]: dpo-drop ip4

 forwarding:   unicast-ip4-chain
  [@0]: dpo-load-balance: [proto:ip4 index:5 buckets:1 uRPF:14 to:[0:0]]
    [0] [@12]: dpo-receive: 0.0.0.0 on local0

接下来，搭建环境学习一下基本转发流程，组网图如下：我们创建2个命名空间tap1和tap2，tap1模拟PC客户端，tap2模拟远程dhcp 服务器。vpp作为DHCP中继代理。

相关配置如下：首先在linux系统上创建2个命名空间:

ip netns add tap1
ip netns add tap2

启动vpp程序，然后在vpp命令行视图中通过exec 命令加载上述组网配置：

creat tap id 1 host-ns tap1 host-if-name tap1

creat tap id 2 host-ns tap2 host-ip4-addr 192.168.1.2/24 host-if-name tap2 host-ip4-gw 192.168.1.1

set interface state tap1 up
set interface ip addr tap1 192.168.2.1/24
set interface state tap2 up
set interface ip addr tap2 192.168.1.1/24


set dhcp proxy server 192.168.3.2 src-address 192.168.10.1
set dhcp proxy server 192.168.1.2 src-address 192.168.10.1

在netns tap2中配置dnsmaq相关配置/etc/dnsmasq.conf,如下：

log-queries
log-facility=/var/log/dnsmasq.log
log-dhcp
dhcp-range=set:tap2,192.168.2.10,192.168.2.200,255.255.255.0,5m

#设置网关地址
dhcp-option=tag:tap2,option:router,192.168.2.1

#设置DNS server地址
dhcp-option=tag:tap2,option:dns-server,114.114.114.114

启动dnsmasq进程：

ip netns exec tap2 dnsmasq -C /etc/dnsmasq.conf

我们可以查询dnsmasq日志，确定dhcp 服务器运行正常

Nov 16 00:16:58 dnsmasq[242831]: started, version 2.90 DNS disabled
Nov 16 00:16:58 dnsmasq[242831]: compile time options: IPv6 GNU-getopt DBus no-UBus i18n IDN2 DHCP DHCPv6 no-Lua TFTP conntrack ipset no-nftset auth cryptohash DNSSEC loop-detect inotify dumpfile
Nov 16 00:16:58 dnsmasq-dhcp[242831]: DHCP, IP range 192.168.2.10 -- 192.168.2.200, lease time 5m
Nov 16 00:17:30 dnsmasq-dhcp[242831]: 1788928788 available DHCP range: 192.168.2.10 -- 192.168.2.200

接下来我们可以启动dhcp 客户端程序。并在vpp中设置trace抓取流程。

ip netns exec tap1 dhclient tap1 &

vpp代码中，设置trace抓包，抓取dhcp交互流程的处理逻辑如下：

#dhcp discover
00:03:29:414728: virtio-input
  virtio: hw_if_index 2 next-index 4 vring 0 len 42
    hdr: flags 0x00 gso_type 0x00 hdr_len 0 gso_size 0 csum_start 0 csum_offset 0 num_buffers 1
00:03:29:414731: ethernet-input
  frame: flags 0x1, hw-if-index 2, sw-if-index 2
  ARP: 02:fe:ef:b8:d3:3a -> 02:fe:cd:a0:69:8e
00:03:29:414736: arp-input
  reply, type ethernet/IP4, address size 6/4
00:03:29:415393: error-drop

  frame: flags 0x1, hw-if-index 1, sw-if-index 1
  IP4: 02:fe:57:94:02:cc -> ff:ff:ff:ff:ff:ff
00:03:32:086295: ip4-input
  UDP: 0.0.0.0 -> 255.255.255.255
    tos 0x10, ttl 128, length 328, checksum 0x3996 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 308, checksum 0x9485
00:03:32:086303: ip4-lookup
    tos 0x10, ttl 128, length 328, checksum 0x3996 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    fib:0 adj:6 flow:0x00000000
  UDP: 0.0.0.0 -> 255.255.255.255
    tos 0x10, ttl 128, length 328, checksum 0x3996 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 308, checksum 0x9485
00:03:32:086318: ip4-udp-lookup
  UDP: src-port 68 dst-port 67
00:03:32:086321: dhcp-proxy-to-server
  DHCP proxy: sent to server 192.168.1.2
  original_sw_if_index: 1, sw_if_index: 1
  DHCP proxy: sent to server 192.168.3.2
  original_sw_if_index: 1, sw_if_index: 1
00:03:32:086338: ip4-lookup
  fib 0 dpo-idx 4 flow hash: 0x00000000
  UDP: 192.168.2.1 -> 192.168.1.2
    tos 0x10, ttl 128, length 342, checksum 0xb533 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 322, checksum 0x0000
  fib 0 dpo-idx 0 flow hash: 0x00000000
  UDP: 192.168.2.1 -> 192.168.3.2
    tos 0x10, ttl 128, length 342, checksum 0xb333 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 322, checksum 0x0000
00:03:32:086343: ip4-rewrite
  tx_sw_if_index 2 dpo-idx 4 : ipv4 via 192.168.1.2 tap2: mtu:9000 next:3 flags:[] 02feefb8d33a02fecda0698e0800 flow hash: 0x00000000
  00000000: 02feefb8d33a02fecda0698e080045100156000000007f11b633c0a80201c0a8
  00000020: 01020044004301420000010106006aa0e31400030000000000000000
00:03:32:086354: ip4-drop
    fib:0 adj:0 flow:0x00000000
  UDP: 192.168.2.1 -> 192.168.3.2
    tos 0x10, ttl 128, length 342, checksum 0xb333 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 322, checksum 0x0000
00:03:32:086357: tap2-output
  tap2 flags 0xc0180005
  IP4: 02:fe:cd:a0:69:8e -> 02:fe:ef:b8:d3:3a
  UDP: 192.168.2.1 -> 192.168.1.2
    tos 0x10, ttl 127, length 342, checksum 0xb633 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 322, checksum 0x0000
00:03:32:086362: error-drop
  rx:tap1
00:03:32:086365: tap2-tx
    buffer 0x9d0ac: current data 0, length 356, buffer-pool 0, ref-count 1, trace handle 0x6
                    l4-cksum-computed l4-cksum-correct l2-hdr-offset 0 l3-hdr-offset 14
  hdr-sz 0 l2-hdr-offset 0 l3-hdr-offset 14 l4-hdr-offset 0 l4-hdr-sz 0
  IP4: 02:fe:cd:a0:69:8e -> 02:fe:ef:b8:d3:3a
  UDP: 192.168.2.1 -> 192.168.1.2
    tos 0x10, ttl 127, length 342, checksum 0xb633 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 322, checksum 0x0000
00:03:32:086384: drop
  ip4-udp-lookup: No error
  
  #dhcp offer
  
00:03:35:090272: virtio-input
  virtio: hw_if_index 2 next-index 4 vring 0 len 354
    hdr: flags 0x00 gso_type 0x00 hdr_len 0 gso_size 0 csum_start 0 csum_offset 0 num_buffers 1
00:03:35:090283: ethernet-input
  frame: flags 0x1, hw-if-index 2, sw-if-index 2
  IP4: 02:fe:ef:b8:d3:3a -> 02:fe:cd:a0:69:8e
00:03:35:090295: ip4-input
  UDP: 192.168.1.2 -> 192.168.2.1
    tos 0xc0, ttl 64, length 340, checksum 0xefc6 dscp CS6 ecn NON_ECN
    fragment id 0x04bf
  UDP: 67 -> 67
    length 320, checksum 0x5678
00:03:35:090303: ip4-lookup
  fib 0 dpo-idx 7 flow hash: 0x00000000
  UDP: 192.168.1.2 -> 192.168.2.1
    tos 0xc0, ttl 64, length 340, checksum 0xefc6 dscp CS6 ecn NON_ECN
    fragment id 0x04bf
  UDP: 67 -> 67
    length 320, checksum 0x5678
00:03:35:090309: ip4-receive
    fib:0 adj:7 flow:0x00000000
  UDP: 192.168.1.2 -> 192.168.2.1
    tos 0xc0, ttl 64, length 340, checksum 0xefc6 dscp CS6 ecn NON_ECN
    fragment id 0x04bf
  UDP: 67 -> 67
    length 320, checksum 0x5678
00:03:35:090317: ip4-udp-lookup
  UDP: src-port 67 dst-port 67
00:03:35:090326: dhcp-proxy-to-client
  DHCP proxy: broadcast to client from 192.168.2.1
  original_sw_if_index: 1, sw_if_index: 1
  opcode:reply hw[type:1 addr-len:6 addr:02fe579402cc] hops0 transaction-ID:0x14e3a06a seconds:768 flags:0x0 client:0.0.0.0 your:192.168.2.155 server:192.168.1.2 gateway:192.168.2.1 cookie:99.130.83.99, option-53: type:offer, option-54: server:192.168.1.2 option-51: skipped option-118: skipped, option-58: renewal:150 option-59: skipped, option-1: subnet-mask:-256 option-28: skipped, option-6: domian-server:72727272, option-3: router:192.168.2.1 option-82: skipped
00:03:35:090353: tap1-output
  tap1 flags 0xc0180005
  IP4: 02:fe:7d:93:bb:6d -> ff:ff:ff:ff:ff:ff
  UDP: 192.168.2.1 -> 255.255.255.255
    tos 0xc0, ttl 64, length 340, checksum 0xb171 dscp CS6 ecn NON_ECN
    fragment id 0x04bf
  UDP: 67 -> 68
    length 320, checksum 0x0000
00:03:35:090356: tap1-tx
    buffer 0x9d0fa: current data 0, length 354, buffer-pool 0, ref-count 1, trace handle 0x8
                    l4-cksum-computed l4-cksum-correct l2-hdr-offset 0 l3-hdr-offset 14
  hdr-sz 0 l2-hdr-offset 0 l3-hdr-offset 14 l4-hdr-offset 0 l4-hdr-sz 0
  IP4: 02:fe:7d:93:bb:6d -> ff:ff:ff:ff:ff:ff
  UDP: 192.168.2.1 -> 255.255.255.255
    tos 0xc0, ttl 64, length 340, checksum 0xb171 dscp CS6 ecn NON_ECN
    fragment id 0x04bf
  UDP: 67 -> 68
    length 320, checksum 0x0000
    #dhcp request
    00:03:35:090597: virtio-input
00:03:35:090600: ethernet-input
  frame: flags 0x1, hw-if-index 1, sw-if-index 1
  IP4: 02:fe:57:94:02:cc -> ff:ff:ff:ff:ff:ff
    tos 0x10, ttl 128, length 328, checksum 0x3996 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 308, checksum 0xe38d
00:03:35:090606: ip4-lookup
  fib 0 dpo-idx 6 flow hash: 0x00000000
  UDP: 0.0.0.0 -> 255.255.255.255
    tos 0x10, ttl 128, length 328, checksum 0x3996 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 308, checksum 0xe38d
00:03:35:090608: ip4-receive
    fib:0 adj:6 flow:0x00000000
  UDP: 0.0.0.0 -> 255.255.255.255
    tos 0x10, ttl 128, length 328, checksum 0x3996 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 308, checksum 0xe38d
00:03:35:090611: ip4-udp-lookup
  UDP: src-port 68 dst-port 67
00:03:35:090612: dhcp-proxy-to-server
  DHCP proxy: sent to server 192.168.3.2
  original_sw_if_index: 1, sw_if_index: 1
  opcode:request hw[type:1 addr-len:6 addr:02fe579402cc] hops0 transaction-ID:0x14e3a06a seconds:768 flags:0x0 client:0.0.0.0 your:0.0.0.0 server:0.0.0.0 gateway:192.168.2.1 cookie:99.130.83.99, option-53: type:request, option-54: server:192.168.1.2 option-50: skipped, option-12: hostname:6c6561726e696e672d767070 option-55: skipped option-82: skipped
00:03:35:090616: ip4-lookup
  fib 0 dpo-idx 4 flow hash: 0x00000000
  UDP: 192.168.2.1 -> 192.168.1.2
    tos 0x10, ttl 128, length 342, checksum 0xb533 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 322, checksum 0x0000
00:03:35:090618: ip4-rewrite
  tx_sw_if_index 2 dpo-idx 4 : ipv4 via 192.168.1.2 tap2: mtu:9000 next:3 flags:[] 02feefb8d33a02fecda0698e0800 flow hash: 0x00000000
  00000000: 02feefb8d33a02fecda0698e080045100156000000007f11b633c0a80201c0a8
  00000020: 01020044004301420000010106006aa0e31400030000000000000000
00:03:35:090621: tap2-output
  tap2 flags 0xc0180005
  IP4: 02:fe:cd:a0:69:8e -> 02:fe:ef:b8:d3:3a
  UDP: 192.168.2.1 -> 192.168.1.2
    tos 0x10, ttl 127, length 342, checksum 0xb633 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 322, checksum 0x0000
00:03:35:090624: tap2-tx
    buffer 0x9f7fa: current data 0, length 356, buffer-pool 0, ref-count 1, trace handle 0x9
                    l4-cksum-computed l4-cksum-correct l2-hdr-offset 0 l3-hdr-offset 14
  hdr-sz 0 l2-hdr-offset 0 l3-hdr-offset 14 l4-hdr-offset 0 l4-hdr-sz 0
  IP4: 02:fe:cd:a0:69:8e -> 02:fe:ef:b8:d3:3a
  UDP: 192.168.2.1 -> 192.168.1.2
    tos 0x10, ttl 127, length 342, checksum 0xb633 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 322, checksum 0x0000
    #dhcp ack
    
    00:03:35:090597: virtio-input
00:03:35:090600: ethernet-input
  frame: flags 0x1, hw-if-index 1, sw-if-index 1
  IP4: 02:fe:57:94:02:cc -> ff:ff:ff:ff:ff:ff
    tos 0x10, ttl 128, length 328, checksum 0x3996 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 308, checksum 0xe38d
00:03:35:090606: ip4-lookup
  fib 0 dpo-idx 6 flow hash: 0x00000000
  UDP: 0.0.0.0 -> 255.255.255.255
    tos 0x10, ttl 128, length 328, checksum 0x3996 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 308, checksum 0xe38d
00:03:35:090608: ip4-receive
    fib:0 adj:6 flow:0x00000000
  UDP: 0.0.0.0 -> 255.255.255.255
    tos 0x10, ttl 128, length 328, checksum 0x3996 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 308, checksum 0xe38d
00:03:35:090611: ip4-udp-lookup
  UDP: src-port 68 dst-port 67
00:03:35:090612: dhcp-proxy-to-server
  DHCP proxy: sent to server 192.168.3.2
  original_sw_if_index: 1, sw_if_index: 1
00:03:35:090616: ip4-lookup
  fib 0 dpo-idx 4 flow hash: 0x00000000
  UDP: 192.168.2.1 -> 192.168.1.2
    tos 0x10, ttl 128, length 342, checksum 0xb533 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 322, checksum 0x0000
00:03:35:090618: ip4-rewrite
  00000000: 02feefb8d33a02fecda0698e080045100156000000007f11b633c0a80201c0a8
  00000020: 01020044004301420000010106006aa0e31400030000000000000000
00:03:35:090621: tap2-output
  tap2 flags 0xc0180005
  IP4: 02:fe:cd:a0:69:8e -> 02:fe:ef:b8:d3:3a
  UDP: 192.168.2.1 -> 192.168.1.2
    tos 0x10, ttl 127, length 342, checksum 0xb633 dscp unknown ecn NON_ECN
    fragment id 0x0000
  UDP: 68 -> 67
    length 322, checksum 0x0000
00:03:35:090624: tap2-tx
    buffer 0x9f7fa: current data 0, length 356, buffer-pool 0, ref-count 1, trace handle 0x9
00:03:35:097735: virtio-input
  virtio: hw_if_index 2 next-index 4 vring 0 len 368
    hdr: flags 0x00 gso_type 0x00 hdr_len 0 gso_size 0 csum_start 0 csum_offset 0 num_buffers 1
00:03:35:097739: ethernet-input
  frame: flags 0x1, hw-if-index 2, sw-if-index 2
  IP4: 02:fe:ef:b8:d3:3a -> 02:fe:cd:a0:69:8e
00:03:35:097742: ip4-input
  UDP: 192.168.1.2 -> 192.168.2.1
    tos 0xc0, ttl 64, length 354, checksum 0xefb6 dscp CS6 ecn NON_ECN
    fragment id 0x04c1
  UDP: 67 -> 67
    length 334, checksum 0xb807
00:03:35:097745: ip4-lookup
  fib 0 dpo-idx 7 flow hash: 0x00000000
  UDP: 192.168.1.2 -> 192.168.2.1
    tos 0xc0, ttl 64, length 354, checksum 0xefb6 dscp CS6 ecn NON_ECN
    fragment id 0x04c1
  UDP: 67 -> 67
    length 334, checksum 0xb807
00:03:35:097747: ip4-receive
    fib:0 adj:7 flow:0x00000000
  UDP: 192.168.1.2 -> 192.168.2.1
    tos 0xc0, ttl 64, length 354, checksum 0xefb6 dscp CS6 ecn NON_ECN
    fragment id 0x04c1
  UDP: 67 -> 67
    length 334, checksum 0xb807
00:03:35:097751: ip4-udp-lookup
  UDP: src-port 67 dst-port 67
00:03:35:097753: dhcp-proxy-to-client
  DHCP proxy: broadcast to client from 192.168.2.1
  original_sw_if_index: 1, sw_if_index: 1
  opcode:reply hw[type:1 addr-len:6 addr:02fe579402cc] hops0 transaction-ID:0x14e3a06a seconds:768 flags:0x0 client:0.0.0.0 your:192.168.2.155 server:192.168.1.2 gateway:192.168.2.1 cookie:99.130.83.99, option-53: type:ack, option-54: server:192.168.1.2 option-51: skipped option-118: skipped, option-58: renewal:150 option-59: skipped, option-1: subnet-mask:-256 option-28: skipped, option-12: hostname:6c6561726e696e672d767070, option-6: domian-server:72727272, option-3: router:192.168.2.1 option-82: skipped
00:03:35:097759: tap1-output
  tap1 flags 0xc0180005
  IP4: 02:fe:7d:93:bb:6d -> ff:ff:ff:ff:ff:ff
  UDP: 192.168.2.1 -> 255.255.255.255
    tos 0xc0, ttl 64, length 354, checksum 0xb161 dscp CS6 ecn NON_ECN
    fragment id 0x04c1
  UDP: 67 -> 68
    length 334, checksum 0x0000
00:03:35:097761: tap1-tx
    buffer 0x9d121: current data 0, length 368, buffer-pool 0, ref-count 1, trace handle 0xa
                    l4-cksum-computed l4-cksum-correct l2-hdr-offset 0 l3-hdr-offset 14
  hdr-sz 0 l2-hdr-offset 0 l3-hdr-offset 14 l4-hdr-offset 0 l4-hdr-sz 0
  IP4: 02:fe:7d:93:bb:6d -> ff:ff:ff:ff:ff:ff
  UDP: 192.168.2.1 -> 255.255.255.255
    tos 0xc0, ttl 64, length 354, checksum 0xb161 dscp CS6 ecn NON_ECN
    fragment id 0x04c1
  UDP: 67 -> 68
    length 334, checksum 0x0000

至此，我们通过搭建环境，了解vpp dhcp中继代理的基本配置及业务转发流程。在搭建环境测试中，还遇到了一些BUG，后续整理之后将提交PR。目前看dhcp 中继代理模块距离商业化还很远。继续打补丁。

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原始发表：2024-11-16，如有侵权请联系 cloudcommunity@tencent.com 删除

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