Transcript draft-wu-softwire-mesh-framework-00

A Framework for Softwire Mesh Signaling,
Routing and Encapsulation
across Backbone Networks
draft-wu-softwire-mesh-framework-00
Jianping Wu
Yong Cui
Xing Li
Tsinghua University / CERNET
Chris Metz
Gargi Nalawade
Simon Barber
Pradosh Mohapatra
Cisco Systems, Inc.
Problem to Solve
• draft-ietf-softwire-problem-statement-02.txt
– describes softwire mesh scenario and
requirements
• Basically we need a generalized, networkbased solution for supporting client IP
AF(i)-over-backbone IP AF(j) routing and
forwarding
– e.g. IPv4-over-IPv6, IPv6-over-IPv4, VPNv6over-IPv4, etc.
CERNET2 Requirements
Same as
a dual-stack
backbone
SW
IPv4 static or eBGP peering
Encapsulation and Setup
IPv4 Access
IPv4 Access
edge
IPv4 Access
edge
edge
CERNET2 Backbone
IPv6 Access
IPv4 Access
edge
IPv6 Access
Native IPv6
backbone
Reference Model of Mesh Solution
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|<------<SW Signaling>------>|
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|<---AF(i)---->|<----<BGP: AF(i)prefixes,-->|<-----AF(i)--->|
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Routing
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SW_NHOP>
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Routing
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+-------+
+-------+
+-------+
+-------+
|AF(i) |
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(Single AF(j))
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|AF(i) |
|Access |------| AFBR |===(Transit Core)===| AFBR |------|Access |
|Island |
|AF(i,j)|
|AF(i,j)|
|Island |
+-------+
+-------+
+-------+
+-------+
/|\
/|\
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[STH]
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---[SPH]---->SW Encap=======[SPH]==========>SW Decap---[SPH]--->
[payload]
[payload]
[payload]
AFBR=Address Family Border Router
SPH=Softwire Payload Header
STH=Softwire Transport Header
Softwire Signaling
BGP Update
RR
IP AF (i)
Access
Island
AFBR
2
.
.
IP AF (i)
Access
Island
IP AF (j)
Transit Core
SW Encap Set
SW Tunn ID
SW End-Point Addr
IP AF (i)
Access
Island
AFBR
1
AFBR
N
= Softwire
• AFBR 1 advertises the following to AFBR 2, …, AFBR N:
– softwire encap set, softwire tunnel ID and softwire end-point
• Now AFBR 2, … AFBR N have learned the SW encap set and SW
tunnel with end-point address to use when forwarding packets to
prefixes advertised by AFBR 1
Softwire Signaling Drafts
•
draft-nalawade-kapoortunnel-safi-05.txt
– defines a new tunnel
SAFI=64 contained in
MP_REACH_NLRI
– NLRI value contains tunnel
ID: tunnel IPv4/IPv6 address
•
draft-nalawade-softwiremesh-encap-attribute-00.txt
– defines a payload type
carried inside softwire
– TLVs for encap types (e.g.
IPnIP, GRE, etc.), encap
parameters, and
preferences
MP_REACH_NLRI
+---------------------------------------------------------+
| AFI (IPv4=1, IPv6=2)
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+---------------------------------------------------------+
| SAFI (TUNNEL=64)
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+---------------------------------------------------------+
| Length of Next Hop Network Address (1 octet)
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+---------------------------------------------------------+
| Network Address of Next Hop (variable)
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+---------------------------------------------------------+
| Reserved (1 octet)
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+---------------------------------------------------------+
| SW Tunnel ID=2 Octets: SW End-Point Address (IPv4/IPv6) |
+---------------------------------------------------------+
Softwire Routing and Tunnel
Selection
BGP Update
RR
IP AF(i) Prefix
specific SW to
use to reach that
prefix
IP AF (i)
Access
Island
AFBR
2
IP AF (j)
Transit Core
AFBR
1
IP AF (i)
Access
Island
= Softwire
• AFBR 1 advertises:
– IP AF(i) prefixes using BGP protocols
– specific softwire-to-use to reach those prefixes (via SW_NHOP)
• SW_NHOP attribute contains:
– pointer to softwire tunnel-to-use leading to AFBR1
– IP AF(j) address that overrides next-hop address contained in
MP_REACH_NLRI
• draft-nalawade-softwire-nhop-00.txt
Additional Softwire Items
• OAM/MIBs
• Security
– control plane via TCP MD5
– data plane via encryption (e.g. IPsec)
– apply L3VPN practices (RFC4111)
• Multicast
– possibilities are tunnel over unicast softwire mesh,
extend mVPN, etc.
• Inter-AS
– Options A, B and C
In summary
• Dynamic and scalable method for IP(x)-over-IP(y)
routing and forwarding needed
• BGP ideal of softwire signaling
– conveys softwire end-point addresses and sw encap sets
• BGP ideal for softwire routing and tunnel selection
– employ existing multi-AF BGP solutions
– include SW_NHOP attribute to link reachability with softwire
encap action and next_hop address
• Re-use existing IP (and MPLS) tunnel encapsulation
schemes
• Generalized for any client IP AF(x)-over-IPv4/IPv6/MPLS
backbones
Next Steps
• Request that the following become
Softwires WG documents
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draft-wu-softwire-mesh-framework-00
draft-nalawade-kapoor-tunnel-safi-05.txt
draft-nalawade-softwire-mesh-encap-attribute-00.txt
draft-nalawade-softwire-nhop-00.txt