Implementing IPv6 Segment Routing David Lebrun - - PowerPoint PPT Presentation

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Implementing IPv6 Segment Routing David Lebrun - - PowerPoint PPT Presentation

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Implementing IPv6 Segment Routing David Lebrun <david.lebrun@uclouvain.be> UCLouvain Netdev 1.2, Tokyo, October 2016 1/35 Table of Contents Segment Routing Implementation Network Function Virtualization Conclusion 2/35 Table of

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Implementing IPv6 Segment Routing

David Lebrun <david.lebrun@uclouvain.be>

UCLouvain

Netdev 1.2, Tokyo, October 2016

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Table of Contents

Segment Routing Implementation Network Function Virtualization Conclusion

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Table of Contents

Segment Routing Implementation Network Function Virtualization Conclusion

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Segment Routing

  • Source routing paradigm
  • State embedded in packet (segments)
  • Segments: node, adjacency, service
  • IETF draft-spring-segment-routing-09
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Segment Routing: illustration (1)

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Segment Routing: illustration (2)

  • Abstract SR Header
  • Segments = SD, SB, SS, SF, SE
  • Ptr = Segments[0] (SD)
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Segment Routing: illustration (3)

  • Abstract SR Header
  • Segments = SD, SB, SS, SF, SE
  • Ptr = Segments[0] (SD)
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Segment Routing: illustration (4)

  • Abstract SR Header
  • Segments = SD, SB, SS, SF, SE
  • Ptr = Segments[1] (SB)
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Segment Routing: illustration (5)

  • Abstract SR Header
  • Segments = SD, SB, SS, SF, SE
  • Ptr = Segments[2] (SS)
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Segment Routing: illustration (6)

  • Abstract SR Header
  • Segments = SD, SB, SS, SF, SE
  • Ptr = Segments[3] (SF)
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Segment Routing: illustration (7)

  • Abstract SR Header
  • Segments = SD, SB, SS, SF, SE
  • Ptr = Segments[4] (SE)
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SR flavors

  • SR-MPLS (segment: 20-bit label)
  • SR-IPv6 (segment: 128-bit IPv6 addr)
  • IPv6 Routing Header extension
  • HMAC TLV for authenticity & integrity
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SR-IPv6

1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Header | Hdr Ext Len | Routing Type | Segments Left | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | First Segment | Flags | RESERVED | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Segment List[0] (128 bits IPv6 address) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | ... | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Segment List[n] (128 bits IPv6 address) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // // // Optional Type Length Value objects (variable) // // // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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HMAC TLV

1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | RESERVED | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | HMAC Key ID (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // // // HMAC (32 octets) // // // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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SR-IPv6 operations (1)

  • Origin SR host: push SRH in packet build
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SR-IPv6 operations (2)

  • SR ingress: encapsulate with outer IPv6 header + SRH
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SR-IPv6 operations (3)

  • Segment endpoint: route packet to next segment
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SR-IPv6 operations (4)

  • SR egress: decapsulate packet and route inner packet to DA
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Segment Routing Implementation Network Function Virtualization Conclusion

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Features

  • SR-enabled packet processing (data plane)
  • SRH insertion/encapsulation (control plane)
  • HMAC support (control + data plane)
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Data plane part (1)

  • net/ipv6/exthdrs.c
  • Processing of Routing Header type 4
  • Decrement segments_left index
  • Update ipv6_hdr(skb)->daddr with next segment
  • Call ip6_route_input(skb)
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Data plane part (2)

  • SRH decapsulation (egress)
  • pull, reset headers, netif_rx
  • tcpdump shows the packet twice
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Control plane part (1)

  • net/ipv6/seg6.c net/ipv6/seg6_iptunnel.c
  • SRH encapsulation (ingress)
  • Lightweight tunnels support
  • ip -6 route add prefix via gw encap seg6 mode

encap segs seg1,seg2,seg3

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Control plane part (2)

  • net/ipv6/ipv6_sockglue.c net/ipv6/exthdrs.c
  • Per-socket SRH insertion (endhost)
  • Pushed by ipv6_push_nfrag_opts
  • Set with setsockopt(fd, IPPROTO_IPV6, IPV6_RTHDR,

...);

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Insertion vs encapsulation

  • Missing support for IPv6 extension headers in drivers
  • ixgbe 0000:0b:00.1:

partial checksum but l4 proto=2b!

  • IPv6 encapsulation works well incl. w/ GRO
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HMAC part (1)

  • net/ipv6/seg6_hmac.c
  • Calls in net/ipv6/exthdrs.c and

net/ipv6/seg6_iptunnel.c

  • Validate SR-enabled packets with HMAC signature
  • Generate valid signature for locally imposed SRHs
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HMAC part (2)

  • HMACKeyID ⇒< algo, secret >
  • Controlled through genetlink interface
  • Interface sysctl seg6_require_hmac
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Table of Contents

Segment Routing Implementation Network Function Virtualization Conclusion

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NFV with SR

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NFV-SR requirements

  • Fast, generic kernel-to-app packet transfer
  • Packet modifiable by app
  • App-to-kernel packet transfer
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NFV-SR attempted solution

  • mmap-ed netlink tx/rx rings
  • Buffering, reordering issues
  • Not GRO-friendly
  • Very specific
  • Removed from mainline
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NFV-SR possible solutions

  • nfqueue w/ NF_REPEAT ?
  • GRO-friendliness issue
  • Interface-based solution ?
  • Suggestions welcome
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Table of Contents

Segment Routing Implementation Network Function Virtualization Conclusion

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Conclusion

  • Draft fully implemented
  • Need driver support for IPv6 extension headers
  • Need packet transfer mechanism for NFV support
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Conclusion

  • Thanks to Cisco and ARC-SDN grant from Fédération

Wallonie-Bruxelles for funding

  • Patch submission by end of October
  • Contact: david.lebrun@uclouvain.be