BRKSPG-3001.pdf

#CLUS
Jakub Horn
Technial Marketing Engineer
BRKSPG-3001
Subtitle goes here
Introduction to SRv6
Technology

© 2019 Cisco and/or its affiliates. All rights reserved. Cisco Public
#CLUS
Agenda
• Introduction
• SRv6 Header Format and Forwarding
• SID Structure and Network Programming
• L3 VPN
• TI-LFA
• Other Applications
• Conclusion
BRKSPG-3001 3

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#CLUS
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BRKSPG-3001

#CLUS
Aggregation
Problem statement: Today’s service creation
Metro/Access Network Domain Core Network Domain Data Center Domain
Limited Cross-domain Automation, Cumbersome Service Assurance
End-to-end service provisioning is lengthy and complex
• Routing protocols are blind to applications (Shortest-path for any traffic)
• Multiple network domains under different management teams
• Manual operations
• Heterogeneous underlay and overlay networks
IP
MPLS (LDP, RSVP-TE)
L2VPN
Ethernet
L3VPN VXLAN
Complex E2E Quality of Service (QoS)
BRKSPG-3001 5

#CLUS
Aggregation
Segment Routing Unified Fabric Vision
SDN
Metro/Access Network Domain
SDN
Core Network Domain
SDN
Data Center Domain
Segment Routing
BGP VPN L2/L3
Homogenous Cross-domain Automation & Assurance
SDN
Control
End-to-end service provisioning is simple and scalable
• Multiple network domains under same management teams
• Automated operations
• Homogenous underlay and overlay networks
BRKSPG-3001 6

#CLUS
SDN
Metro Network Domain
SDN
Core Network Domain
SDN
Data Center Domain
Aggregation
Homogenous Cross-domain Automation & Assurance
End-to-end service provisioning is simple
• Multiple network domains under same management teams
• Automated operations
• Homogenous underlay and overlay networks
Centralized Services Delivery
Segment Routing
VPN L2/L3
SR-MPLS: SDN ready
“Network as a Fabric” for Service Creation
Cloud Scale Networking
Central Office
Access
Compute Leaf Spine
VNF VNF
VNF
VNF
SDN
Control
BRKSPG-3001 7

#CLUS
IPv6 SR Header
• IPv6 header
• Next header field: Indicates what comes next
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Traffic Class | Flow Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length | Next Header | Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Source Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Destination Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BRKSPG-3001 9

#CLUS
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port | Destination Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Source Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 SR Header
• IPv6 header
• Next header field: 17 → UDP
17
BRKSPG-3001 10

#CLUS
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| IHL |Type of Service| Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification |Flags| Fragment Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time to Live | Protocol | Header Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Source Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 SR Header
• IPv6 header
• Next header field: 4 → IPv4
4
BRKSPG-3001 11

#CLUS
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port | Destination Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Acknowledgment Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data | |U|A|P|R|S|F| |
| Offset| Reserved |R|C|S|S|Y|I| Window |
| | |G|K|H|T|N|N| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Checksum | Urgent Pointer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Source Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 SR Header
• IPv6 header
• Next header field: 6 → TCP
6
BRKSPG-3001 12

#CLUS
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Source Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. type-specific data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 SR Header
• IPv6 header
• Next header field: 43 → Routing
• IPv6 Routing extension header
• Generic header format defined in RFC 2460
• Next Header: IPv4, TCP, UDP, …
• Hdr Ext Len: Any IPv6 device can skip this header
• Segments Left: Ignore extension header if equal to 0
• Specific data depends on Routing Type field:
• 0 Source Route (deprecated since 2007)
• 1 Nimrod (deprecated since 2009)
• 2 Mobility (RFC 6275)
• 3 RPL Source Route (RFC 6554)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | Segments Left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
43
BRKSPG-3001 13

#CLUS
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Source Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| First Segment | Flags | Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Segment List[0] (128 bits IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. ... .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Segment List[n-1] (128 bits IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
// Optional Type Length Value objects (variable) //
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 SR Header
• IPv6 header
• Next header field: 43 → Routing
• IPv6 Routing extension header
• Generic header format defined in RFC 2460
• Next Header: IPv4, TCP, UDP, …
• Hdr Ext Len: Any IPv6 device can skip this header
• Segments Left: Ignore extension header if equal to 0
• Specific data depends on Routing Type field:
• 0 Source Route (deprecated since 2007)
• 1 Nimrod (deprecated since 2009)
• 2 Mobility (RFC 6275)
• 3 RPL Source Route (RFC 6554)
• 4 Segment Routing (tentative)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4
43
RFC
2460
SR
specific

#CLUS
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Source Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| First Segment | Flags | Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. ... .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Segment List[n-1] (128 bits IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 SR Header
• Each segment is an IPv6 address
• Segments are encoded in reverse
order
• Last segment index is 0
• First segment index is First Segment
• Active segment index is Segments Left
• Active Segment is copied in the
Destination Address field of the IP
header
• Additional data can be stored in TLVs
• Security (HMAC), NFV metadata, …
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4
43
First Segment
@Segment List [First Segment]
Last Segment / Final Destination
@Segment List [0]
Active Segment
Active Segment
@Segment List [Segments Left]

#CLUS
SR Header Processing
BRKSPG-3001 16

#CLUS
Source Node
• Source node is SR-capable
• SR Header (SRH) is created with
• Segment list in reversed order of the path
• Segment List [ 0 ] is the LAST segment
• Segment List [ 𝑛 − 1 ] is the FIRST segment
• Segments Left is set to 𝑛 − 1
• First Segment is set to 𝑛 − 1
• IP DA is set to the first segment
• Packet is send according to the IP DA
• Normal IPv6 forwarding
Version Traffic Class
Next = 43 Hop Limit
Payload Length
Source Address = A::
Destination Address = B::
Segment List [ 0 ] = D::
Segment List [ 1 ] = C::
Next Header Len= 6 Type = 4 SL = 2
First = 2 Flags RESERVED
IPv6
Hdr
Segment List [ 2 ] = B::
SR
Hdr
Payload
Flow Label
Flow Label
D
D::
A
A::
SR Hdr
IPv6 Hdr SA = A::, DA = B::
( D::, C::, B:: ) SL=2
Payload
B
B::
C
C::
BRKSPG-3001 17

#CLUS
Non-SR Transit Node
• Plain IPv6 forwarding
• Solely based on IPv6 DA
• No SRH inspection or update
D
D::
A
A::
SR Hdr
IPv6 Hdr SA = A::, DA = B::
( D::, C::, B:: ) SL=2
Payload
B
B::
C
C::
BRKSPG-3001 18

#CLUS
SR Segment Endpoints
• SR Endpoints: SR-capable nodes
whose address is in the IP DA
• SR Endpoints inspect the SRH and do:
• IF Segments Left > 0, THEN
• Decrement Segments Left ( -1 )
• Update DA with Segment List [ Segments Left ]
• Forward according to the new IP DA
Next = 43 Hop Limit
Payload Length
Destination Address = C::
IPv6
Hdr
SR
Hdr
Payload
Flow Label
Flow Label
D
D::
A
A::
B
B::
C
C::
SR Hdr
IPv6 Hdr SA = A::, DA = C::
( D::, C::, B:: ) SL=1
Payload
BRKSPG-3001 19

#CLUS
SR Segment Endpoints
• SR Endpoints: SR-capable nodes
whose address is in the IP DA
• SR Endpoints inspect the SRH and do:
• IF Segments Left > 0, THEN
• Decrement Segments Left ( -1 )
• Update DA with Segment List [ Segments Left ]
• Forward according to the new IP DA
• ELSE (Segments Left = 0)
• Remove the IP and SR header
• Process the payload:
• Inner IP: Lookup DA and forward
• TCP / UDP: Send to socket
• …
Next = 43 Hop Limit
Payload Length
Destination Address = D::
IPv6
Hdr
SR
Hdr
Payload
Flow Label
Flow Label
D
D::
A
A::
B
B::
C
C::
SR Hdr
IPv6 Hdr SA = A::, DA = D::
( D::, C::, B:: ) SL=0
Payload
Standard IPv6
processing
The final destination
does not have to be
SR-capable.
BRKSPG-3001 20

#CLUS
Segment format
• SRv6 SIDs are 128-bit addresses
• Locator: most significant bits are used to route the segment to its parent node
• Function: least significant bits identify the action to be performed on the parent node
• Argument [optional]: Last bits can be used as a local function argument
• Flexible bit-length allocation
• Segment format is local knowledge on the parent node
• SIDs have to be specifically enabled as such on their parent node
• A local address is not by default a local SID
• A local SID does not have to be associated with an interface
1111 : 2222 : 3333 : 4444 : 5555 : 6666 : 7777 : 8888
Locator Function
BRKSPG-3001 22

#CLUS
END – Default endpoint
• Default endpoint behavior (node segment)
• Decrement Segments Left, update DA
• Forward according to new DA
• Node B advertises prefix B::/64 (B::/64 is the SID locator)
• Packets are forwarded to B along the default routes (shortest path)
• On B, the default endpoint behavior is associated with ID 0 (0 is the function)
• The SID corresponding to the default endpoint behavior on node B is B::0
SR Hdr
IPv6 Hdr SA = A::, DA = B::0
(…,C::,B::0,…) SL=k
Payload
B
B:: /64
SR Hdr
(…,C::,B::0,…) SL=k-1
Payload
C
BRKSPG-3001 23

#CLUS
END.X – Endpoint then Xconnect
• Endpoint xconnect behavior (adjacency segment)
• Forward on the interface associated with the Xconnect segment
• Node C advertises prefix C::/64
• Packets are forwarded to C along the default routes (shortest path)
• On C, the endpoint xconnect behavior for link (C, E) is associated with ID CE
• The SID corresponding to endpoint xconnect-(C,E) behavior on node C is C::CE
SR Hdr
IPv6 Hdr SA = A::, DA = C::C1
(…,D::, C::C1,…) SL=k
Payload
SR Hdr
(…,D::,C::C1,…)SL=k-1
Payload
C
C:: /64
D
1
2
BRKSPG-3001 24

#CLUS
END.DX4 – Endpoint with Decapsulation and
Xconnect (END.DX6, END.DX2)
• Segments Left must be 0
• NH must be IPv4 (or IPv6 or L2)
• Decapsulate inner packet
• Forward on the interface associated with the Xconnect
• Node D advertises prefix C::/64
• Packets are forwarded to D along the default routes (shortest path)
• On C, the endpoint xconnect behavior for link (D, E) is associated with ID DE
• It is like L3 VPN with per CE label allocation
SR Hdr
IPv6 Hdr SA = A::, DA = D::D1
(…, D::C1) SL=0
IPv4 packet
IPv4 packet
D
D:: /64
1
2
BRKSPG-3001 25

#CLUS
END.DT4 – Endpoint with Decapsulation and
Table lookup(END.DT6)
• Segments Left must be 0
• NH must be IPv4 (or IPv6)
• Decapsulate inner packet
• Do the lookup for IPv4 destination of inner packet and forward accordingly
• Node D advertises prefix D::/64
• Packets are forwarded to D along the default routes (shortest path)
• On C, the endpoint behavior for link (D, E) is associated with ID CE
• It is like L3 VPN with per VRF label allocation
SR Hdr
IPv6 Hdr SA = A::, DA = D::1
(…, D::1) SL=0
IPv4 packet
IPv4 packet
D
D:: /64
1
2
BRKSPG-3001 26

#CLUS
Transit behavior T.ENCAP and T.INSERT
Payload X
IPv6 Hdr SA = E::, DA = F::
SR Hdr (B::, C::,F::) SL=2
Payload X IPv6 Hdr SA = A::, DA = D::
Payload
Payload
SR Hdr (D::, B::,C::) SL=2
BRKSPG-3001 27

#CLUS
IPv6 Hdr SA = D::, DA = S1
SR Hdr (…, E::, D::10,… ) SL=k-1
Payload
IPv6 Hdr SA = A::, DA = E::
SR Hdr (S3, S2, S1) SL=2
END.B6.ENCAPS – IPv6 Binding Segment
(encap)
• IPv6 binding segment
• Push outer IP and SR headers associated with the binding segment
• Forward according to outer header DA (first segment of the new SRH)
• The SR encaps policy (SA = D::, SL = 〈 S1, S2, S3 〉) is associated with ID 10
• The corresponding binding SID is D::10
SR Hdr
(…,E::,D::10,…) SL=k
Payload
D
D:: /64
BRKSPG-3001 28

#CLUS
IPv6 Hdr SA = A::, DA = S1
SR Hdr (…,E::, D::20,…) SL=k
Payload
SR Hdr ( S3, S2, S1 ) SL=2
END.B6 – IPv6 Binding Segment (insert)
• IPv6 binding segment
• Do not decrement Segments Left
• Push outer SR header associated with the binding segment
• Update DA with the first segment of the outer SR header
• Forward according to outer header DA (first segment of the new SRH)
• On D, the SR insert policy 〈 S1, S2, S3 〉 is associated with ID 20
SR Hdr
(…,E::, D::20,…) SL=k
Payload
D
D:: /64
BRKSPG-3001 29

#CLUS
MPLS { L1, L2, L3 }
SR Hdr (…,E::, D::20,…) SL=k-1
Payload
IPv6 Hdr SA = A::, DA = E::
END.BM – MPLS Binding Segment
• MPLS binding segment
• Decrement Segments Left
• Push outer MPLS label stack associated with the binding segment
• Forward according to the top MPLS label
• On D, the MPLS SR policy { L1, L2, L3 } is associated with ID 30
SR Hdr
(…,E::, D::30,…) SL=k
Payload
D
D:: /64
BRKSPG-3001 30

#CLUS
Functions might be signaled differently
Signalling IGP BGP-
LS
BGP-
IP/VPN
End Yes Yes
End.X Yes Yes
End.T Yes Yes
End.DX4 Yes Yes
End.DX6 Yes Yes Yes
End.DX2 Yes Yes
END.DT4 Yes Yes
End.DT6 Yes Yes Yes
End.B Yes
Signalling IGP BGP-
LS
BGP-
IP/VPN
T.insert Yes
T.Encap Yes
Locator – routing table
BRKSPG-3001 32

#CLUS
ISIS easily extensible
• Uses TLVs
• For Srv6:
• Locator – for Reachability (twice for
backward compatibility)
• END function - TI-LFA and TE
• END.X function for each interface in
routing protocol TI-LFA and TE
• Capabilities:
• Max SID depth for different functionn
• OSPF will follow
Ten0/0/0/0
Lo0
A::1/128
2001::12/64
Locator : B::/64
END: B::1
END.X: B::41
Ten0/0/0/1
END.X: B::42
fe80::dead/64
Router 1
BRKSPG-3001 33

#CLUS
ISIS example
r12.00-00 * 0x00000978 0x5eea 611 /* 0/0/0
Area Address: 49
NLPID: 0x8e
Hostname: r12
IPv6 Address: 2001::2
Metric: 10 MT (IPv6 Unicast) IPv6 2001::2/128
Prefix Attribute Flags: X:0 R:0 N:1
Metric: 1 MT (IPv6 Unicast) IPv6 2001:0:0:2::/64
Router Cap: 0.0.0.0 D:0 S:0
IPv6 Router ID: 2001::2
SRv6: O:0
Node Maximum SID Depth:
SRH Max SL: 5
SRH Max End Pop: 6
SRH Max T.insert: 5
SRH Max T.encaps: 5
SRH Max End D: 6
SRv6 Locator: MT (IPv6 Unicast) 2001:0:0:2::/64 D:0 Metric: 0 Algorithm: 0
END SID: 2001:0:0:2:1:: End (PSP)
MT: IPv6 Unicast 0/0/0
Metric: 10 MT (IPv6 Unicast) IS-Extended r11.00
Interface IPv6 Address: 2001:0:0:12::2
Neighbor IPv6 Address: 2001:0:0:12::1
END.X SID: 2001:0:0:2:40:: B:0 S:0 P:0 End.X (PSP)
Metric: 10 MT (IPv6 Unicast) IS-Extended r13.00
Interface IPv6 Address: 2001:0:0:23::2
Neighbor IPv6 Address: 2001:0:0:23::3
END.X SID: 2001:0:0:2:41:: B:0 S:0 P:0 End.X (PSP)
Locator
Capabilities
END
END.X
BRKSPG-3001 34

#CLUS
Basic SRv6 VPN –Control Plane
• BGP needs to allocate function for each local prefix
• Two possibilities
• Per VRF allocation –one END.DT function allocated
• Per CE allocation – END.DX function is allocated for each BGP peer in
VRF
• END.DT is allocated by default and advertised with local prefixes, and
static routes
BRKSPG-3001 35

#CLUS
1
5
2
3
VPNv4 Basic Control Plane
4
SRv6
CE CE
eBGP
eBGP
IPv4 :1.1.1.0/24
VPNv4 address family
IPv4 :1.1.1.0/24 – END.DX A:3::45
IPv4 :1.1.1.0/24
END.DX4
A:3::45
iBGP
Locator A:3::/64
Locator A:1::/64
BRKSPG-3001 36

#CLUS
1
5
2
3
VPNv4 Basic Data Plane
4
SRv6
CE CE
eBGP
eBGP
IPv4 :1.1.1.0/24
VPNv4 address family
IPv4 :1.1.1.0/24 – END.DX A:3::45
IPv4 :1.1.1.0/24
END.DX4
A:3::45
iBGP
Locator A:3::/64
Locator A:1::/64
SA:2.2.2.2
DA:1.1.1.1
NH:UDP
UDP Header/Data
SA:A:1::1
DA:A:3::45
NH:IPv4
SA:2.2.2.2
DA:1.1.1.1
NH:UDP
UDP Header/Data
SA:2.2.2.2
DA:1.1.1.1
NH:UDP
UDP Header/Data
BRKSPG-3001 37

#CLUS
TI-LFA
• Topology Independent Loop Free Alternate
• Fast Convergence
• To be fast it has to be LOCAL
• No signalling
• No reprograming FIB
• <50ms is considered fast convergence
BRKSPG-3001 39

#CLUS
1
5
2
3
NO TI-LFA -Before Failure
4
SRv6
CE CE
Destination is END.DX4 – A:3::45
Whole network knows how to reach A:3::/64
Metric 100
BRKSPG-3001 40

#CLUS
1
5
2
3
NO-TI-LFA
4
SRv6
CE CE
Failure –Fiber CUT between R2-R3 time T0
Failure Detection T1 (LOS or BFD) (1-100ms)
Propagation of Failure to IGP T2 (2ms-20ms)
IGP Creates new LSP
IGP sends new LSP to R1- T3 (~4ms)
IGP Runs SPF and creates new RIB-FIB entry (1-3000 ms)
HW programming on R2 (1-3ms)
Discarding
Metric 100
BRKSPG-3001 41

#CLUS
1
5
2
3
NO-TI-LFA R2 Convergence
4
SRv6
CE CE
R1 Received new LSP -T4 (5us/km)
R1 IGP Takes LSP and propagates it to R5 -T5 (~1-20ms)
R1 IGP Runs SPF and creates new RIB-FIB entry
HW programming on R1
uLoop
Metric 100
BRKSPG-3001 42

#CLUS
1
5
2
3
4
SRv6
CE CE
R5 Received new LSP –T6 (5us/km)
R5 IGP Takes LSP and propagates it to R5 (~1-20ms)
R5 IGP Runs SPF and creates new RIB-FIB entry
HW programming on R5 T7
uLoop
Metric 100
BRKSPG-3001 43

#CLUS
1
5
2
3
4
SRv6
CE CE
A:3::/64
R5 Received new LSP T6 (5us/km)
R5 Takes LSP and propagates it to R4
R5 IGP Runs SPF and creates new RIB-FIB entry (1-3000ms)
HW programming on R5 T7 (1-5ms)
Metric 100
BRKSPG-3001 44

#CLUS
1
5
2
3
ISIS enable SRv6
4
IPv6 only
LocatorA:2::/64
END A:2::1
END.X A:2::21
END.X A:2::23
LocatorA:1::/64
END A:1::1
END.X A:1::12
END.X A:1::15
LocatorA:3::/64
END A:3::1
END.X A:3::32
END.X A:3::34
LocatorA:4::/64
END A:4::1
END.X A:4::43
END.X A:4::45
LocatorA:5::/64
END A:5::1
END.X A:5::51
END.X A:5::54
BRKSPG-3001 45

#CLUS
1
5
2
3
TI-LFA before Failure - Calculating Backup Path
4
SRv6
CE CE
Router 2
Link to Router 3
Prefix A:3::/64
P -Space
All Routers R1 can reach
without crossing the link 2-3
Q -Space
All Routers that can reach destination
without crossing the link 2-3
Metric 100
BRKSPG-3001 46

#CLUS
1
5
2
3
Failure
4
CE CE
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:3::45
NH:IPv6
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:5::54
NH:RH
Type:4(SRH)
NH:IPv4|SL:1
Segment List:
[0]: A:3::45
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:3::45
NH:IPv4
Failure –Fiber CUT between R2-R3 time T0
Failure Detection T1 (LOS or BFD) (1-100ms)
Single HW Interrupt to switch to preprogrammed backups (1-15ms)

#CLUS
1
5
2
3
Converged
4
CE CE
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:3::45
NH:IPv4
BRKSPG-3001 48

#CLUS
1
5
2
3
What About Microloop
4
CE CE
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:3::45
NH:IPv6
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:5:41::
NH:IPv4
IGP Creates new LSP
IGP sends new LSP to R1- T3
IGP Runs SPF and creates new RIB-FIB entry
HW programming on R2 (1-3ms)
BRKSPG-3001 49

#CLUS
1
5
2
3
Microloop Avoidance- Local
4
CE CE
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:3::45
NH:IPv6
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:5::54
NH:RH
Type:4(SRH)
NH:IPv4|SL:1
Segment List:
[0]: A:3::45
IGP Creates new LSP
IGP sends new LSP to R1- T3
IGP Runs SPF and creates new RIB-FIB entry
WAIT WAIT WAIT give some time to R1 to do his job
HW programming on R2

#CLUS
1
5
2
3
R1 Converged
4
CE CE
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:3::45
NH:IPv4
But R5 still have old information……
Maybe still doing SPF….
BRKSPG-3001 51

#CLUS
1
5
2
3
R1 Converged
4
CE CE
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:5::54
NH:RH
R1 does not install postconvergence FIB entry immediately
He gives some more time to R5
Type:4(SRH)
NH:IPv4|SL:1
Segment List:
[0]: A:3::45
BRKSPG-3001 52

#CLUS
1
5
2
3
Converged
4
CE CE
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:6.6.6.6
DA:7.7.7.7
NH:UDP
UDP Header/Data
SA:A::1
DA:A:3::45
NH:IPv6
BRKSPG-3001 53

#CLUS
Flexible Algorithm
• We call “Flex-Algo”
• The algorithm is defined by the operator, on a per-deployment basis
• Flex-Algo K is defined as
• The minimization of a specified metric: IGP, delay, …
• The exclusion of certain link properties: link-affinity, SRLG, …
• Example
• Operator1 defines Flex-Algo 128 as “minimize IGP metric and avoid link-affinity
“green”
• Operator2 defines Flex-Algo 128 as “minimize delay metric and avoid link-affinity
“blue”
55
BRKSPG-3001

#CLUS
1
3
2 4
L3VPN VRF1
5
6
7
8
IGP
10
IGP
30
IGP
30
IGP
10
IGP
10
IGP
20
IGP
10 IGP
10
IGP
10
IGP
10
IGP
10
IGP
30
IGP
10 CE
CE
eBGP
eBGP
iBGP
IPv4 :1.1.1.0/24
IPv4 :1.1.1.0/24 – END.DX A:8::45
IPv4 :1.1.1.0/24
Locator A:1::/64 Locator A:8::/64
END.DX4
A:8::45
BRKSPG-3001 56

#CLUS
1
3
2 4
L3VPN
5
6
7
8
IGP
10
IGP
30
IGP
30
IGP
10
IGP
10
IGP
20
IGP
10 IGP
10
IGP
10
IGP
10
IGP
10
IGP
30
IGP
10 CE
CE
iBGP
IPv4 :1.1.1.0/24 – END.DX A:8::45
Locator 2001:0:0:8::/64
END.DX4
A:8::45
SA:A::1
DA:A:8::45
NH:IPv4
SA:2.2.2.2
DA:1.1.1.1
NH:UDP
UDP Header/Data
SA:2.2.2.2
DA:1.1.1.1
NH:UDP
UDP Header/Data
BRKSPG-3001 57

#CLUS
1
3
2 4
Flex ALGO 128
5
6
7
8
Delay
1ms
Delay
5ms
Delay
15ms
Delay
20ms
Delay
5ms
Delay
5ms
Delay
1ms Delay
1ms
Delay
15ms
Delay
10ms
Delay
5ms
Delay
20ms
Delay
1ms CE
CE
SRv6 Locator
A:801::/64
SRv6 Locator
A:808::/64
SRv6 Locator
A:802::/64
SRv6 Locator
A:804::/64
SRv6 Locator
A:803::/64
SRv6 Locator
A:805::/64
SRv6 Locator
A:806::/64
SRv6 Locator
A:807::/64
Definition:
Metric-Delay
Exclude link BLUE
BRKSPG-3001 58

#CLUS
Link Delay Measurement Protocol
Querier Responder
PM Response Packet
PM Query Packet
TX Timestamp T1 RX Timestamp T2
One-Way Delay = (T2 – T1)
Two-Way Delay = (T4 – T1) – (T3 – T2)
One-Way Delay = Two-Way Delay/2
TX Timestamp T3
RX Timestamp T4
A::1
A::2
PM Query and Response using
RFC 6374 packet format
• For one-way delay measurement, hardware clocks must be
synchronized using PTP (IEEE 1588) between querier and responder
nodes.
BRKSPG-3001 59

#CLUS
1
3
2 4
L3VPN VRF f128
5
6
7
8 CE
CE
eBGP
eBGP
iBGP
IPv4 :3.3.3.0/24
IPv4 :3.3.3.0/24 – END.DX A:808::44
IPv4 :3.3.3.0/24
Locator Flex ALGO 128
A:808::/64
END.DX4
A:808::44
Delay
1ms
Delay
5ms
Delay
15ms
Delay
20ms
Delay
5ms
Delay
5ms
Delay
1ms
Delay
10ms
Delay
5ms
BRKSPG-3001 60

#CLUS
1
3
2 4
L3VPN VRF f128
5
6
7
8 CE
CE
iBGP
IPv4 :3.3.3.0/24 – END.DX A:808::44
A:808::/64
END.DX4
A:808::44
Delay
1ms
Delay
5ms
Delay
15ms
Delay
20ms
Delay
5ms
Delay
5ms
Delay
1ms
Delay
10ms
Delay
5ms
SA:A::1
DA:A:808::44
NH:IPv4
SA:2.2.2.2
DA:3.3.3.3
NH:UDP
UDP Header/Data
SA:2.2.2.2
DA:3.3.3.3
NH:UDP
UDP Header/Data
BRKSPG-3001 61

#CLUS
1
3
2 4
All Together
5
6
7
8 CE
CE
A:808::/64
END.DX4 FA128
A:808::44
SA:A::1
DA:A:808::44
NH:IPv4
SA:2.2.2.2
DA:3.3.3.3
NH:UDP
UDP Header/Data
SA:2.2.2.2
DA:3.3.3.3
NH:UDP
UDP Header/Data
SA:A::1
DA:A:8::45
NH:IPv4
SA:2.2.2.2
DA:1.1.1.1
NH:UDP
UDP Header/Data
SA:2.2.2.2
DA:1.1.1.1
NH:UDP
UDP Header/Data
END.DX4 FA0
A:8::45
Locator Flex ALGO 0
A:8::/64
BRKSPG-3001 62

#CLUS
UPF
5G Core (Service Based) Architecture
AMF SMF PCF
UPF
AF
(R)AN
UE Control
Data
N1 N2
N4
N9
N3 N6
DN
NSSF
NG-RAN, Fixed
Nnssf Nausf
Nudm
Nnef Nnrf
Namf Nsmf Npcf Naf
NEF NRF
APIs (HTTP/JSON)
BSF
Nbsf
SEPP
Other
PLMN
Nudr
AUSF UDM UDR NWDAF
Nwdaf
CHF
Nchf
SMSF
Nsmsf
AF Application Function
AMF Access and Mobility Management Function
AUSF Authentication Server Function
BSF Binding Support Function
CHF Charging Function
DN Data Networks
NEF Network Exposure Function
NRF NF Repository Function
NSSF Network Slice Selection Function
NWDAF Network Data Analytics Function
PCF Policy Control Function
SMF Session Management Function
SMSF SMS Function
SEPP Security Edge Protection Proxy
(R)AN (Radio) Access Network
UPF User Plane Function
UDM Unified Data Management
UDR Unified Data Repository
BRKSPG-3001 64

#CLUS
GTP = GPRS Tunneling Protocol
• GSM 9.60 -1996
• 3 Versions: 0,1,2
• 2 Flavours
• GTP-C (Can be v1 and v2)
• GTP-U (Always v1) IP4/6 Carrier
IP4/6 Customer
UDP
GTP
L2
UPF
gNB
UE
Internet
BRKSPG-3001 65

#CLUS
GTPv1 header format
3GPP TS 29.281
UDP port 2152
Version – 1 (for v1)
Protocol Type – 1 (0 used for charging)
Extension Header, Sequence Number, N-PDU Number – optional
Message type, Message Length used for GTP-C
TEID –Tunnel Endpoint Identifier (random number)
BRKSPG-3001 66

#CLUS
IETF
• Segment Routing IPv6 for Mobile User Plane
• https://tools.ietf.org/html/draft-ietf-dmm-srv6-mobile-uplane-03
• Segment Routing IPv6 for mobile user-plane PoCs
• https://tools.ietf.org/html/draft-camarillo-dmm-srv6-mobile-pocs-01
End.MAP -Endpoint function with SID mapping
End.M.GTP6.D -Endpoint function with IPv6/GTP decapsulation into SR policy
End.M.GTP6.E -Endpoint function with encapsulation for IPv6/GTP tunnel
End.M.GTP4.E -Endpoint function with encapsulation for IPv4/GTP tunnel
T.M.Tmap -Transit with tunnel decapsulation and map to an SRv6 policy
End.Limit -Rate Limiting Function
BRKSPG-3001 67

#CLUS
IETF -Modes
UPF
(R)AN
UE
N9
DN
UPF
N3 N6
SRv6 Node SRv6 Node SRv6 Node
SRv6
SRv6
Traditional
Enhanced (Traffic Engineering, Service Programming)
TE
(R)AN
UE
N3
DN
UPF
N3 N6
SRv6 Node SRv6 Node SRv6 Node
SRv6
SRv6
CNF
N3
SRv6
SRv6 Node
Enhanced with unchanged gNB (Interworking)
UPF
(R)AN
UE
N9
DN
UPF
N3 N6
SRv6 Gateway SRv6 Node
SRv6
GTP
BRKSPG-3001 68

#CLUS
3GPP
• 3GPP TR 29.892
• Study on User Plane Protocol in 5GC (R16)
BRKSPG-3001 69

#CLUS
3GPP
BRKSPG-3001 70

#CLUS
GTP-U Conclusion
• GTP is legacy protocol
• GTP has significant overhead (especially for 5G with extension header)
• GTP is load balancing unfriendly (can be used by using IPv6 + flow label)
• We can encapsulate GTP into SRV6 
• SRv6 can do the same as GTP
• SRv6 provides natural link between Mobile and Transport
BRKSPG-3001 71

#CLUS
Service Chaining
Packets are steered through a sequence of services on their way to the destination.
BRKSPG-3001 73

#CLUS
Service Chaining – traditional approach
Packets are steered through a sequence of services on their way to the
destination.
• Services are placed on the traffic route
• Static configurations
• Traffic bottlenecks
BRKSPG-3001 74

#CLUS
Service Chaining with NSH
• Dedicated encapsulation header
• Per-chain state to be maintained at every hop (SFF)
BRKSPG-3001 75

#CLUS
• Services are expressed with segments
• Flexible
• Scalable
• Stateless
Service Chaining with SR
S1 S2 S3 D
SR: 〈S1, S2, S3, D〉
BRKSPG-3001 76

#CLUS
SRv6 service segments
• SID instantiated on an SRv6 router / host connected to the service
• Send with SRH to SRv6-capable device
• Use proxy function to remove / hide SRH before sending to SRv6 unaware service
• SID instantiated on an SRv6 aware service
• Traffic processing depends on the SID
e.g.
• F1::10 → Firewall F1 with rule-set 10
• F1::20 → Firewall F1 with rule-set 20
BRKSPG-3001 77

#CLUS
Service segments in SR architecture
Just another type of segment
• Stateless in the fabric
• Seamless integration with VPN and/or TE
• Service is opaque to the head-end and intermediate nodes
S1
S2
S3
D
SR: 〈S1, C1, S2, S3, D〉
C1
BRKSPG-3001 78

#CLUS
Services
• SR-Aware: Service is bound to an SR endpoint function
• Processes all the traffic passing through the node
or is triggered by a specific endpoint function
• SR-UnAware: Service is not able to process SR traffic
• Requires an SR proxy to operate properly
S1
D
SR: 〈S1, C1, S2, S3, D〉
C1
S2 S3
BRKSPG-3001 79

#CLUS
SRH metadata carrier
• Tag
• 16-bit opaque field
• Hardware friendly
• “Poor man’s” metadata
• TLVs
• Flexible encoding and length
• Designed for software processing
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Last Entry | Flags | Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
...
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Segment List[n] (128 bits IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BRKSPG-3001 81

#CLUS
SRH opaque metadata TLV
• Type: TBA
• Length: 14
• Service Metadata: 14 octets of opaque data
 Similar to NSH’s MD Type 1
0 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 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
| Service Metadata |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BRKSPG-3001 82

#CLUS
VNF
VPC
All nodes in green are SRv6 capable
Server
2
Server
1
Internet
AWS Oregon
AWS North Virginia
AWS Ireland
VPP
VPC
VPP
VPC
VPP
IPv6 Hdr SA = A:1::, DA = B:2:A::
SR Hdr ( B:3:DC2::, B:2:A:: ) SL=1
IPv4 Hdr SA = 1.1.1.0, DA = 2.2.2.2
Payload
IPv4 Hdr SA=1.1.1.0, DA=2.2.2.2
Payload
IPv4 Hdr SA=1.1.1.0, DA=2.2.2.2
Payload
IPv6 Hdr SA = A:2::, DA = B:3:DC2::
SR Hdr ( B:3:DC2:, B:2:A:: ) SL=0
IPv4 Hdr SA = 1.1.1.0, DA = 2.2.2.2
Payload
Multi-cloud overlays
• Interconnect cloud-based services
• Different cloud regions
• Different cloud providers
• Plain IPv6 transit over the Internet
BRKSPG-3001 83

#CLUS
Service Programming Conclusion
• Current approach is inefficient
• NSH is stateful hence not scalable
• SRv6 is stateless
• There are VNFs supporting SRv6 already
• For legacy VNF we will use proxy functionality
• TLVs allow to use metadata to carry additional information
• SRv6 concept is ready for microservices
• SRv6 excellent for cloud based application
• Any function can be anywhere
BRKSPG-3001 84

#CLUS
Locator Function Argument
1111 : 2222 : 3333 : 4444 : 5555 : 6666 : 7777 : 8888
r1 r2
IPv6 Network
Locator
A1::/64
Locator
B2::/64
Function
::a
Function
::b
A1::/64
B2::/64
SRv6 Locator-Function
Locator = Reachability= pure routing
IGP or BGP or…….
Function = Service provisioning
BGP, Controller ….
BRKSPG-3001 86

#CLUS
r1 r2
IPv6 Network
A
Locator
A:1::/64
Locator
B:2::/64
SRv6 Scale
IPv6 Network
B
r3
B:2::/64
A:1::/64
B::/16 A::/16
Unlike MPLS, no /32 nor /64 needed
BRKSPG-3001 87

#CLUS
r1 r2
IPv6
Network
A1
Locator
A:1:1::/64
Locator
B:1:2::/64
SRv6 Massive Scale
IPv6 Network
A2
r3
A:1:4::/64
B::/16
::/0
IPv6 Network
B2
IPv6 Network
B1
IPv6 Network
C
IPv6 Network
D
r4
Locator
A:1:4::/64
r5
Locator
A:2:1::/64
Locator
C:0:1::/64
r6
A:2::/32
C::/16
B::/16
A::/16
D::/16
D::/16
BRKSPG-3001 88

#CLUS
SRv6 Ecosystem
2018
ISIS SRv6 w/ TILFA (NfV ; END.AS)
L3 Service (IPv4 L3VPN)
SRv6 OAM (Ping/Trace)
2019
SRv6 for Internet (v4/v6, VPNv6)
SRv6 Flex-Algo
Multi-plane, Delay optimized
L2 P2P Service (EVPN VPWS)
SRv6/MPLS Gateway
 END.AS
 END.AD
 END.ASM
 END.AM
Linux / FD.io
Open-Source Applications
Pyroute2 SERA
NfV Partners
Smart NIC
BRKSPG-3001 90

#CLUS
SRv6 Support
ASR9000
XR 6.6.1
SRv6 Transport (ISIS)
Service (IPv4 L3VPN)
TILFA (ISIS)
SRv6 OAM (Ping/Trace)
NCS540
NCS5500
BRKSPG-3001 91

#CLUS
• SRv6 is Here
• It is ready for greenfield
• It has wide opensource support
• Massive Scale!
• Stateless Service Chaining –Network Programming
• Can Replace GTP
BRKSPG-3001 92
Conclusion

#CLUS
More IPv6 Sessions
93
BRKSPG-3001
When Session Title
10 June 2019/ 8:00 BRKRST-2619 IPv6 Deployment: Developing an IPv6 Addressing Plan and Developing IPv6
12 June / 8:00 BRKMPL-2132 Designing and deploying SRv6 networking
12 June / 13:00 BRKRST-3304 Hitchhiker's Guide to Troubleshooting IPv6
12 June / 8:00 BBRKRST-3122 Segment Routing: Technology Deep Dive and Advanced Use Cases
LABRST-2261 IPv6 planning, deployment and transition
LABSPG-1327 Introduction to Segment Routing v6 (SRv6) with IOS-XR

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#CLUS BRKSPG-3001 94

#CLUS
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