Explaining the source code of VPP SRv6/GTP-U translation developed in IETF 104 Hackathon. (Partially in Japanese)

1. VPP Prototyping for
Stateless SRv6/GTP-U Translation
FD.io / VPP ユーザ有志の会 #1
2019/05/28 ＠東京ミッドタウン
Kentaro Ebisawa | Twitter: @ebiken
IETF 104 Hackathon Implementation
VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン

2. VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
SRv6 on VPP (Vector Packet Processing)
https://fd.io/technology/
• Input as Packet Vector
• Process based on graph of nodes
(ethernet, mpls, ip6, arp …)
• New functionality could be added by
customizing node or creating plugin
SRv6 node: sr_localsid_node, sr_policy_*_node
DPDK (User Land)

3. VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
SRv6 on VPP (by FD.io project)
Supported functions as of 2019/05/27
http://www.segment-routing.net/open-software/vpp/

4. VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
IETF 104 Hackathon @Prague, Czech
https://trac.ietf.org/trac/ietf/meeting/wiki/104hackathon

5. VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
IETF 104 Hackathon @Prague, Czech
Target Function Description
End.MAP Forwards the receiving IPv6 packet and update the IPv6 DA
with mapped SID.
End.M.GTP6.D Decap the receiving GTP/UDP/IPv6 packet and encap with
IPv6 header, or IPv6 header with SRH based on the
address/ID mapping rule and binding SR-Policy
End.M.GTP6.E Decap the receiving IPv6+SRH packet and encap with
IPv6/UDP/GTP-U header based on the address/ID mapping
rule.
End.M.GTP4.E
(SRv6 -> GTP-U)
Decap the receiving IPv6+SRH packet and encap with
IPv4/UDP/GTP-U header base on the address/ID mapping
rule.
T.M.Tmap
(GTP-U -> SRv6)
Decap the receiving GTP/UDP/IPv4 packet and encap with
IPv6 header, or IPv6 header with SRH based on the
address/ID mapping rule and binding SR-Policy.
End.Limit Limit the throughput of the packet flow with mapped SID.
**NEW** Translate GTP-U Echo Request to ICMP Echo Request and vice
versa
**NEW** Translate GTP-U Echo Reply to ICMP Echo Request and vice
versa

6. VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
Hackathon Topology and CLI (ConfigCommands)
Hack target
VPP1
VPP4
D4::
IPv4 over GTP/UDP/IPv4 IPv4 over SRH/IPv6
VPP2
D2::
IPv4 over IPv6 IPv4 over GTP/UDP/IPv4
T.M.Tmap End.M.GTP4.E
VPP3
D3::
scapy scapy
T.M.Tmap
sr policy add bsid <bsid> next A1:: next B1:: next C1:: (weight 5) (fib-table 3) gtp4_removal
sr-prefix <ipv6_prefix_interworking>/<mask> local-prefix <src_prefix>/<mask>
sr steer l3 <IPv4 dst addr of GTP-U>/<mask> via bsid <bsid>
End.M.GTP4.E
sr localsid (del) address <IPv6 address of SRGW>/<mask> behavior end.m.gtp4.e

7. • https://wiki.fd.io/view/VPP/Software_Architecture
• VLIB
• Vnet
• https://wiki.fd.io/view/VPP/Feature_Arcs
• https://wiki.fd.io/view/VPP/DPOs_and_Feature_Arcs
VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
VPP Architecture Reference (Wiki Pages)

8. POC SRv6 Implementations
VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
Extending SRv6 functions
https://docs.fd.io/vpp/19.04/srv6_plugin_doc.html
$ git clone https://gerrit.fd.io/r/vpp
~/vpp/src/examples/srv6-sample-localsid$ ls
node.c srv6_localsid_sample.h
srv6_localsid_sample.c
srv6_sample_localsid_doc.md

9. VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
SRv6 on VPP (Vector Packet Processing)
src/vnet/srv6$ grep VLIB_REGISTER_NODE *
sr_localsid.c:VLIB_REGISTER_NODE (sr_localsid_d_node) = {
sr_localsid.c:VLIB_REGISTER_NODE (sr_localsid_node) = {
sr_policy_rewrite.c:VLIB_REGISTER_NODE (sr_policy_rewrite_encaps_node) = {
sr_policy_rewrite.c:VLIB_REGISTER_NODE (sr_policy_rewrite_encaps_v4_node) = {
sr_policy_rewrite.c:VLIB_REGISTER_NODE (sr_policy_rewrite_encaps_l2_node) = {
sr_policy_rewrite.c:VLIB_REGISTER_NODE (sr_policy_rewrite_insert_node) = {
sr_policy_rewrite.c:VLIB_REGISTER_NODE (sr_policy_rewrite_b_insert_node) = {
sr_policy_rewrite.c:VLIB_REGISTER_NODE (sr_policy_rewrite_b_encaps_node) = {

10. VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
SRv6 on VPP (Vector Packet Processing)
src/plugins$ grep -r VLIB_REGISTER_NODE | grep srv6
srv6-gtp/node.c:VLIB_REGISTER_NODE (srv6_gtp_node) = {
srv6-end/node.c:VLIB_REGISTER_NODE (srv6_end_m_gtp4_e) = {
srv6-ad/node.c:VLIB_REGISTER_NODE (srv6_ad_localsid_node) = {
srv6-ad/node.c:VLIB_REGISTER_NODE (srv6_ad2_rewrite_node) = {
srv6-ad/node.c:VLIB_REGISTER_NODE (srv6_ad4_rewrite_node) = {
srv6-ad/node.c:VLIB_REGISTER_NODE (srv6_ad6_rewrite_node) = {
srv6-am/node.c:VLIB_REGISTER_NODE (srv6_am_localsid_node) = {
srv6-am/node.c:VLIB_REGISTER_NODE (srv6_am_rewrite_node) = {
srv6-as/node.c:VLIB_REGISTER_NODE (srv6_as_localsid_node) = {
srv6-as/node.c:VLIB_REGISTER_NODE (srv6_as2_rewrite_node) = {
srv6-as/node.c:VLIB_REGISTER_NODE (srv6_as4_rewrite_node) = {
srv6-as/node.c:VLIB_REGISTER_NODE (srv6_as6_rewrite_node) = {

11. VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
https://github.com/filvarga/srv6-mobile
https://github.com/filvarga/srv6-mobile/tree/ietf104-hackathon/extras/ietf104

12. VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
Finding modified source code
Last commit before IETF Hackathon
1d85b1eef299bcdaa4df193fa70b7c90e9b2809f
Pablo Test Implementation
srv6-gtp

13. VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
Finding modified source code
ebiken@lab:~/20190527-vppug/srv6-mobile$ git diff --name-only 1d85b1eef299bcdaa4df193fa70b7c90e9b2809f
extras/ietf104/Dockerfile.j2
extras/ietf104/README.md
extras/ietf104/requirements.txt
extras/ietf104/runner.py
extras/ietf104/startup.conf.j2
src/plugins/srv6-ad/ad.c
src/plugins/srv6-ad/node.c
src/plugins/srv6-end/CMakeLists.txt
src/plugins/srv6-end/node.c
src/plugins/srv6-end/srv6_end.c
src/plugins/srv6-end/srv6_end.h
src/vnet/dpo/dpo.c
src/vnet/srv6/sr.h
src/vnet/srv6/sr_api.c
src/vnet/srv6/sr_policy_rewrite.c
test/test_srv6_end.py
ebiken@lab:~/20190527-vppug/srv6-mobile$ git branch -a
* ietf104-hackathon
remotes/origin/HEAD -> origin/ietf104-hackathon
remotes/origin/ietf104-hackathon
remotes/origin/master
remotes/origin/satoru
Generic Code.
CLI/Configuration.
T.M.Tmap のコード
End.M.GTP4.E : src/plugins/srv6-end/

14. diff 調査メモ
VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
add plugins
src/plugins/srv6-end/CMakeLists.txt src/plugins/srv6_gtp.am
srv6-endがhackathonで実装したコード

15. • src/vnet/srv6/sr.h
• GTPU Header 構造体（ip4_gtpu_header_t）の定義
• T.M.TmapのFlagやlocal_prefixの追加（line 94,95）
• sr_policy_add のプロトタイプ宣言
VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
diff 調査メモ

16. • src/vnet/srv6/sr_policy_rewrite.c
• T.M.Tmap の実装
• Registration
• VLIB_REGISTER_NODE (sr_policy_rewrite_encaps_v4_node) = {
$ diff --git a/src/vnet/srv6/sr_policy_rewrite.c b/src/vnet/srv6/sr_policy_rewrite.c
sr_policy_rewrite_encaps_v4 (vlib_main_t * vm, vlib_node_runtime_t * node,
VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
diff 調査メモ

17. • src/plugins/srv6-end$
• End.M.GTP4.Eの実装
• Registration
• VLIB_REGISTER_NODE (srv6_end_m_gtp4_e) = {
VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
diff 調査メモ

18. > src/plugins/srv6-end/node.c
211 VLIB_REGISTER_NODE (srv6_end_m_gtp4_e) = {
212 .name = "srv6-end-m-gtp4-e",
213 .vector_size = sizeof (u32),
214 .format_trace = format_srv6_end_rewrite_trace,
215 .type = VLIB_NODE_TYPE_INTERNAL,
217 .n_errors = ARRAY_LEN (srv6_end_error_strings),
218 .error_strings = srv6_end_error_strings,
VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
diff 調査メモ
220 .n_next_nodes = SRV6_END_M_GTP4_E_N_NEXT,
221 .next_nodes = {
222 [SRV6_END_M_GTP4_E_NEXT_DROP] = "error-drop",
223 [SRV6_END_M_GTP4_E_NEXT_LOOKUP] = "ip4-lookup",
224 },
225 };

19. Appendix
VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン

20. POC SRv6 Implementations
VPP Prototyping for Stateless SRv6/GTP-U Translation | FD.io / VPP ユーザ有志の会 #1 | 2019/05/28 ＠東京ミッドタウン
Extending SRv6 functions
https://docs.fd.io/vpp/19.04/srv6_plugin_doc.html $ git clone https://gerrit.fd.io/r/vpp
~/vpp/src/examples/srv6-sample-localsid$ ls
node.c srv6_localsid_sample.h
srv6_localsid_sample.c srv6_sample_localsid_doc.md