Transcript OSPF Link Overload

OSPF Link Overload
draft-hegde-ospf-link-overload
Shraddha Hegde
Hannes Gredler
Pushpasis Sarkar
Agenda
• Problem
• Motivation
• Solution
• OSPF protocol details
• Conclusion
Overlay networks
CE
Blue2
PE1
PE3
PE2
PE4
CE
Blue
1
CE
Red2
CE
Red1
Overlay network
Problems
• Traffic needs to be diverted away from the overlay
links when the underlying network devices go for
maintenance.
• It’s difficult to manually configure every remote
end to divert the traffic when PEs go for
maintenance/upgradation
Overlay Broadcast networks
CE
Red4
PE1
PE3
PE2
PE4
CE
Red3
CE
Red2
CE
Red1
Overlay network over IRB
interface
Motivation
• Ease of maintenance
• Automated upgradation
• Minimized traffic loss
Solution
P2P links
• Advertise a link overload TLV in Extended Link
Opaque LSA
• Remote end identifies connecting link
• Increases metric to MAX-METRIC
• Re-floods Router LSA
• Traffic is diverted away from overloaded link
• Overlay Link is ready for maintenance
Solution
Broadcast links
• Advertise a link overload TLV in Extended Link
Opaque LSA
• DR for the link recognizes the new TLV
• Removes the TLV Originating router from list of
connected neighbors in Network LSA
• Re-floods Network LSA
• Traffic is diverted away from overloaded link
• Overlay Link is ready for maintenance
TLV details
0
1
2
3
01234567890123456789012345678901
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Type
|
Length
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Remote IP address
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Remote IP address distinguishes the link when there are two parallel links
between the nodes. Remote-IP address is zero in case of broadcast links.
Questions?
THANKS