draftamanteisisreversemetric 01 Authors Shane Amante Tony Li Naiming Shen Mikael Abrahamsson Proposed Status Standards Track Background Operational reqmt to gracefully bidirectionally ID: 583419
Download Presentation The PPT/PDF document "Reverse Metric TLV" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Reverse Metric TLVdraft-amante-isis-reverse-metric-01
Authors:Shane AmanteTony LiNaiming ShenMikael Abrahamsson
Proposed Status: Standards TrackSlide2
Background
Operational reqm’t to gracefully bi-directionally remove both p2p links and multi-access LAN’s from the ISIS topology, except as a link of last-resortDO NOT need or want to isolate the entire router with IS-IS overload-bit – potentially affecting Tbps of ‘innocent’ trafficLogin to CLI of both (p2p) or all (LAN) devices and increase the existing IS-IS metric(s) to temporarily remove it from the topologyService Providers don’t, can’t and/or won’t use NMS to ‘automate’ this
2
draft-amante-isis-reverse-metric-00Slide3
Current Link/LAN Isolation Procedures
Current procedure to isolate link/LAN:login to each router,correctly identify specific link on both routersChange existing, configured metric high to extremely high valueIS-IS domain should now consider Link/LAN as “link/LAN of last resort” To un-isolate link/LAN:(Re-)login to each router,Correctly identify specific link/LANChange metric back to originally configured value
R1
R2
R1
R2
R3
R4
R5
R6
P2P Link
Multi-access LAN
3
draft-amante-isis-reverse-metric-00Slide4
Challenges with link/LAN isolationCorrectly identify the corresponding link on two or, more routers, each with hundreds of interfaces apiece @ 3AM in the morning …
Need to temporarily change the existing, configured IS-IS metric on an interface (need to “remember” what it was to properly reset it afterward).Cannot bidirectionally isolate a single adjacency on a multi-access LAN.draft-amante-isis-reverse-metric-004Slide5
Solution: Reverse Metric TLVReverse Metric is
wholly separate from, but added to, existing configured default metric on local device and remote neighborLogin to a single node and temporarily assert an additive high metric in both:Our own IS Reachbility or Ext. IS Reachability TLV’sA Reverse Metric TLV in IIH’s xmit’ed toward your neighbor, on p2p link, or toward DIS on multi-access LANRouter receiving Reverse Metric TLV adds to his/her own existing ‘default metric’ in Pseudonode LSP, IS Reachability or Ext. IS
Reachability
TLV
draft-amante-isis-reverse-metric-00
5Slide6
Proposed Link/LAN Isolation Procedures
Read draft or see slides online for specific proposed link/LAN procedures
R1
R2
R2
R3
R4
R5
R6
P2P Link
Multi-access LAN
6
draft-amante-isis-reverse-metric-00
IIH PDU’s with
Reverse Metric TLV
R2 New LSP
R1 New LSP
R1 New LSP
R1Slide7
Current StatusLAN’s: This draft has similar concerns with persistent forwarding loops if nodes do not accumulate non-zero metric in Pseudonode
LSP, as already discussed for draft-shen-isis-oper-enhanceAddressed large # of comments on mailing list in -00 -01 versionQuestions? Comments?Interest in advancing this draft, in the future?draft-amante-isis-reverse-metric-00
7Slide8
Backup Material(Detailed Procedures)Slide9
Proposed p2p Link Isolation ProceduresR1 Procedures:
login to one router, (R1)correctly identify specific linkApply new, additive IS-IS metric with extremely high value to link – leave existing, configured metric “as is”.In no particular order:Update own IS Reachability, Ext. IS Reachability TLVFlood new LSP’sRecalculate SPF TreeAdd Reverse Metric TLV to IIH PDU’s toward neighbor(s) – R1 R2R2 Procedures:
When R2 receives Reverse Metric TLV
In no particular order:
Add “metric value” in Reverse Metric TLV
to own IS Reachability or Ext. IS Reachability TLV’s of link on which Reverse Metric TLV is recv’d
Flood new LSP’s
Recalculate SPF Tree
draft-amante-isis-reverse-metric-00
9Slide10
Proposed p2p Link Un-Isolation ProceduresR1 Procedures:
login to one router, (R1)correctly identify specific linkRemove additive IS-IS metric with extremely high value to link – leave existing, configured metric “as is”.In no particular order:Update own IS Reachability, Ext. IS Reachability TLVFlood new LSP’sRecalculate SPF TreeStop sending Reverse Metric TLV in IIH PDU’s toward neighbor(s) – R1 R2R2 Procedures:
When R2 stops receiving Reverse Metric TLV
In no particular order:
Remove additive “metric value” (from Reverse Metric TLV)
in own IS Reachability or Ext. IS Reachability TLV’s of link on which Reverse Metric TLV was formerly recv’d
Flood new LSP’s
Recalculate SPF Tree
draft-amante-isis-reverse-metric-00
10Slide11
Proposed multi-access LAN Isolation ProceduresR4 (Non-DIS) Procedures:
login to one router, (R4)correctly identify specific linkApply new, additive IS-IS metric with extremely high value to link – leave existing, configured metric “as is”.On R4 (non-DIS), in no particular order:Update own IS Reachability, Ext. IS Reachability TLVFlood new LSP’sRecalculate SPF TreeAdd Reverse Metric TLV to IIH PDU’s toward DIS – R4 R1R1 (DIS) Procedures:
When R1 receives Reverse Metric TLV
:
Update Pseudonode LSP with non-zero metric – add “metric value” in Reverse Metric TLV – to either R4 (W=0) or all nodes on LAN (W=1)
Flood new Pseudonode LSP
Recalculate SPF Tree
draft-amante-isis-reverse-metric-00
11
Other non-DIS nodes on same LAN,
(R3, R5, R6), ignore Reverse Metric TLV
from R4; however, each will receive
Updated
Psuedonode
LSP from DIS
And recalculate their SPF for otherNode(s) attached to the LAN. Slide12
Proposed multi-access LAN Un-Isolation ProceduresR4 (Non-DIS) Procedures:
login to one router, (R4)correctly identify specific linkRemove additive IS-IS metric with extremely high value to link – leave existing, configured metric “as is”.On R4 (non-DIS), in no particular order:Update own IS Reachability, Ext. IS Reachability TLVFlood new LSP’sRecalculate SPF TreeStop sending Reverse Metric TLV to IIH PDU’s toward DIS – R4 R1R1 (DIS) Procedures:
When R1 stops receiving Reverse Metric TLV
:
Update Pseudonode LSP back to original, zero metric
based on previous assertion in the Reverse Metric TLV from R4, i.e.: just R4 (W=1) or Whole LAN (W=0)
Flood new Pseudonode LSP
Recalculate SPF Tree
draft-amante-isis-reverse-metric-00
12
Other non-DIS nodes on same LAN,
(R3, R5, R6), receive new
Psuedonode
LSP
from DIS and recalculate their SPF for other
node(s) attached to the LAN.