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33Joint-techs Boulder © 2002, Cisco Systems, Inc. All rights reserved. 3 Problem review: “This old fish…” R8 R2 R6 R3 R4 R7 R5 R1 Flows from R8 and R1 Merge at R2 and Become Indistinguishable From R2, Traffic to R3, R4, R5 Use Upper Route Alternate Path may be required “by policy” for R1
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1Joint-techs Boulder © 2002, Cisco Systems, Inc. All rights reserved.
Explicit Routing: the fish at 4+yrs
Larry DunnManager, Advanced Architecture
22Joint-techs Boulder © 2002, Cisco Systems, Inc. All rights reserved. 2
Agenda
• Problem review• Requirements• Example topology• General architecture/solution classes• Example: Early binding• Example: Late binding• Invitation: routing working group
33Joint-techs Boulder © 2002, Cisco Systems, Inc. All rights reserved. 3
Problem review: “This old fish…”
R8
R2
R6
R3R4
R7
R5
R1
Flows from R8 and R1 Merge at R2 and Become IndistinguishableFlows from R8 and R1 Merge at R2 and Become IndistinguishableFrom R2, Traffic to R3, R4, R5 Use Upper RouteFrom R2, Traffic to R3, R4, R5 Use Upper Route
Alternate Path may be required “by policy” for R1Alternate Path may be required “by policy” for R1
44Joint-techs Boulder © 2002, Cisco Systems, Inc. All rights reserved. 4
Requirements
• Accommodate >1 class of traffic (e.g., Abilene-eligible, vs. not-eligible). Some have more classes (e.g., carrier selection).
• Amounts to overriding “normal IP routing” somewhere in the network
• Evaluation metrics: robustness/fragility, performance, complexity(for humans and routers), scalability, $$
55Joint-techs Boulder © 2002, Cisco Systems, Inc. All rights reserved. 5
Example topology
School-D-eligible
School-B-ineligible
DestinationSchool-E
Abilene
School-A-eligible
Commodity ISP1
School-C-ineligible
GigapopCommodity ISP2
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General Architecture Classes
• “Early binding”Decision made close(r) to the sourceDecision must be conveyed to the gigapop (VC, Label, DLCI, tunnel, TOS-overload, etc.)
• “Late binding”Gigapop router does multi-field classification (typically source-prefix)Everybody else just does “regular forwarding”
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Example: Early binding #1: MPLS/VPNs
School-A-eligible
Commodity ISP1
School-C-ineligible
Abilene
GigapopCommodity ISP2
School-D-eligible
School-B-ineligible
(tunnel FIB)
(eligible, non-tunnel FIB,includes Abilene)
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Ex: Early binding #2: generalized tunnels
School-A-eligibleCommodity ISP1
School-C-ineligible
Abilene
GigapopCommodity ISP2
School-D-eligible
School-B-ineligible
(normal FIBfor ineligible)
(three trivial entries,one per ISP)
Route server
BGP to dist. routes; schools choosew/in policy, use tunnel(GRE, FR, MPLS,whatever) to deliver pkts to trivial FIBs.Ineligible schools just do “normal routing”.
99Joint-techs Boulder © 2002, Cisco Systems, Inc. All rights reserved. 9
Example: Late binding (at gigapop)
School-A-eligible
Commodity ISP1
School-C-ineligible
Abilene
GigapopCommodity ISP2
School-D-eligible
School-B-ineligible
(ineligible FIB)
(eligible FIB,includes Abilene)
Schools do “normal routing”, gigapop router uses multi-fieldclassification (typ. Src-prefix) to choose routing table
1010Joint-techs Boulder © 2002, Cisco Systems, Inc. All rights reserved. 10
Invitation: routing working group
• Today, 5:00pm..7:45p(max), at conf. hotel• Merit folks’ routing registry discussion• Deeper discussion of architectural options• Your thoughts/ideas (see yourself here?)• More detailed presos from {Juniper,Cisco}
(implementation, customer feedback, etc.)
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Summary
• Fish problem: been around a long time• Early solutions: multiple boxes, ATM• Today: better understanding of possible
architectures; getting field experience• Advice: use the least complicated
mechanism that will work for your environment ;-)
12© 2001, Cisco Systems, Inc. All rights reserved.QoS Update
1313Joint-techs Boulder © 2002, Cisco Systems, Inc. All rights reserved. 13
Routing w.g. Architecture follow-up
• Taxonomy/solution families• Early binding: policy,security, other facets• Late binding: policy, security• Open discussion
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Taxonomy/solution_families
Generalized tunnelsMPLS/VPNs
TOS_overload
Port-based
Src-addr/5-tuple/else
Early bindingLate binding
Notes: 1. Single-box, multiple-box decision is orthogonal2. Combinations are possible/expected3. Often, the “early-binding” solutions look like a distributed version of late-binding
(Normal IP routing)
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Early binding (gen. tunnels): policy, security, other facets
School-A-eligibleCommodity ISP1
School-C-ineligible
Abilene
GigapopCommodity ISP2
School-D-eligible
School-B-ineligible
(normal FIBfor ineligible)
(three trivial entries,one per ISP)
Route server
BGP to dist. routes; schools choosew/in policy, use tunnel(GRE, FR, MPLS,whatever) to deliver pkts to trivial FIBs.Ineligible schools just do “normal routing”.
Note: carried to extreme, gigapop starts to feel like an (indirect)L2-exchange
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Late binding: policy, security
School-A-eligible
Commodity ISP1
School-C-ineligible
Abilene
GigapopCommodity ISP2
School-D-eligible
School-B-ineligible
(ineligible FIB)
(eligible FIB,includes Abilene)
Schools do “normal routing”, gigapop router uses multi-fieldclassification (typ. Src-prefix) to choose routing table
1717Joint-techs Boulder © 2002, Cisco Systems, Inc. All rights reserved. 17
Open discussion
• Is issue significant to you? • Timeframe?• Implementation stories?• Your topology/complexity?• Other useful models/hybrids?
