VPP/NAT

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VPP NAT implementation

Introduction

The VPP SNAT is an implementation of NAT44. It is a plugin and is meant to replace the VCGN component. The target use case is a general IPv4 CPE NAT, a CGN and to act as a NAT44 in a Openstack deployment.

It is intended to be pluggable, in the sense that it should be possible to plug the NAT44 function together with the MAP-E IPv4 to IPv6 translator to create a MAP-E CE, likewise one can plug the NAT44 together with MAP-T to create a MAP-T CE or 464XLAT.

Features are tracked as they are developed in the following VPP-441.

Until code is upstreamed it is developed on gitub.

Requirements

  • Scale to millions of bindings
  • Performance goal of 10Mpps/core.
  • Configurable address and port selection algorithm.
  • User quotas for sessions.
  • Thread safe
  • Efficient port utilisation. Endpoint independent for applications requiring it, address and port filtering otherwise
  • No ALGs
  • Configurable IP address pooling behavour
  • Plugable with MAP-E/T to create MAP-E/T CE, 464XLAT
  • Stateful NAT64
  • Support for NAT on a stick (single inside / outside interface)

Work list

Task Owner Priority Status Description
1:1 NAT Matus 0 Committed VPP-339
1:1 NAT with ports Matus 0 Committed VPP-339
1:1 NAT with disabled dynamic translation Matus 0 Committed VPP-339 add "static mapping only [connection tracking]" to snat startup config.
VRF awareness Matus 0 Committed VPP-339 One tenant == One VRF. One VRF == multiple interfaces / multiple subnets, add vrf to static mapping API/CLI.
1:1 NAT delete and dump API Matus 0 Committed VPP-339
SNAT: Delete and dump addresses Matus 0 Committed VPP-453
Multiple inside interface - Multiple subnets Matus 0 Verified, works fine VPP-447 Multiple inside interfaces for the same "tenant" with non-overlapping address space.
Inside overlapping interfaces Matus 0 Committed VPP-446 Tenants on separate interfaces, separate VRFs with overlapping address space.
Thread safe Matus 0 Committed VPP-443 All traffic corresponding to a specific session to be handled by a CPU core.
SNAT: Dump API for in and out interfaces Matus 0 Committed VPP-459
SNAT: Address range overlapping Matus 0 Committed VPP-478
API (Java and Python) 0 Done HONEYCOMB-135 SNAT - Honeycomb
SNAT: make test Matus DONE
Hairpinning Matus 1 DONE VPP-444 Hosts communicating behind the same NAT using the external representation of their address. hairpinning
Logging Matus 1 WIP VPP-445 Netflow - IPFix
Configurable Port Allocation Algorithms 1 CGN. High efficiency port utilisation.
Configurable IP address pooling behaviour 1 CGN.
Performance 10Mpps/core. Linear scaling with number of cores.
Scale 10 million sessions.
Input ACL support before NAT
Multiple outside interfaces
ICMP error packet translation
MAP-E CE 1
DS-lite
NAT64
IP fragmentation

API

add S-NAT plugin address range: 

define snat_add_address_range {
 u32 client_index;
 u32 context;
 u8 is_ip4;
 u8 first_ip_address[16];
 u8 last_ip_address[16];
 u8 is_add;
};

dump S-NAT plugin addresses: 

define snat_address_dump {
 u32 client_index;
 u32 context;
};

define snat_address_details {
 u32 context;
 u8 is_ip4;
 u8 ip_address[16];
};

enable/disable S-NAT feature on the interface: 

define snat_interface_add_del_feature {
 u32 client_index;
 u32 context;
 u8 is_add;
 u8 is_inside;
 u32 sw_if_index;
};

add/del 1:1 NAT: 

define snat_add_static_mapping {
 u32 client_index;
 u32 context;
 u8 is_add;
 u8 is_ip4;
 u8 addr_only;
 u8 local_ip_address[16];
 u8 external_ip_address[16];
 u16 local_port;
 u16 external_port;
 u32 vrf_id;
};

dump 1:1 NAT: 

define snat_static_mapping_dump {
 u32 client_index;
 u32 context;
};

define snat_static_mapping_details {
 u32 context;
 u8 is_ip4;
 u8 addr_only;
 u8 local_ip_address[16];
 u8 external_ip_address[16];
 u16 local_port;
 u16 external_port;
 u32 vrf_id;
};

show S-NAT plugin config: 

define snat_show_config {
 u32 client_index;
 u32 context;
};

define snat_show_config_reply {
 u32 context;
 i32 retval;
 u8 static_mapping_only;
 u8 static_mapping_connection_tracking;
 u32 translation_buckets;
 u32 translation_memory_size;
 u32 user_buckets;
 u32 user_memory_size;
 u32 max_translations_per_user;
 u32 outside_vrf_id;
 u32 inside_vrf_id;
};

set S-NAT plugin workers: 

define snat_set_workers {
 u32 client_index;
 u32 context;
 u64 worker_mask;
};

dump S-NAT plugin workers: 

define snat_worker_dump {
 u32 client_index;
 u32 context;
};

define snat_worker_details {
 u32 context;
 u32 worker_index;
 u32 lcore_id;
 u8 name[64];
};

CLI

set interface snat in <intfc> out <intfc> [del]
snat add addresses <ip4-range-start> [- <ip4-range-end>]
snat add static mapping local <ip4-addr> [<port>] external <ip4-addr> [<port>] [vrf <table-id>] [del]
set snat workers <workers-list>
show snat [detail|verbose]

Enable S-NAT feature example

To enable NAT feature with local network interface GigabitEthernet0/8/0 and external network interface GigabitEthernet0/a/0 use: 

vpp# set interface snat in GigabitEthernet0/8/0 out GigabitEthernet0/a/0

1:1 NAT example

To create static mapping between local address 10.0.0.3 and external address 4.4.4.4 use: 

vpp# snat add static mapping local 10.0.0.3 external 4.4.4.4

1:1 NAT with ports example

If not runnig "static mapping only" S-NAT plugin mode first use: 

vpp# snat add address 4.4.4.4

To create static mapping between local host address 10.0.0.3 port 6303 and external address 4.4.4.4 port 3606 use: 

vpp# snat add static mapping local 10.0.0.3 6303 external 4.4.4.4 3606

Set S-NAT workers example

To set S-NAT workers (2 or more workers available, by default S-NAT use all available worker threads) use: 

vpp# set snat workers 0-1

Startup config

translation hash buckets <n> - default 1024
translation hash memory <n> - default 128<<20
user hash buckets <n> - default 128
user hash memory <n> - default 64<<20
max translations per user <n> - default 100
outside VRF id <table-id> - default 0
inside VRF id <table-id> - default 0
static mapping only [connection tracking] - default dynamic traslations enabled

YANG model

References

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