All-Path Bridging Update
Jun Tanaka (Fujitsu Labs. Ld.)
Guillermo Ibanez (UAH)
Vinod Kumar (Tejas Networks)
IEEE Plenary meeting San Francisco 17-21 July
All-Path : Basic Idea
x
Blocking
x
MAC=a
Flooding
MAC=b
• Modified learning, filtering and forwarding
• Addressed to small and medium size networks
• Objectives: overcome RSTP limitations and obtain good
latency paths without configuration
Scope of All-Path
Both support, loop free, shortest path
Manageability
SPB, ECMP
TRILL
Enterprise, Campus,
Small datacenter etc.
LAN
ALL-PATH
 Simple
 Less operation
 Natural load balance
Large area, provider network
Large datacenter etc.
MAN/WAN
Scalability
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Issue1. Path Recovery
• Mechanism: When unknown unicast frame arriving at bridge with
failed link, path fail message is generated per MAC entry towards
source bridge, that generates corresponding ARP to re-establish tree.
• Question: If 10K MAC entries are existed in FDB, 10K path fail frames
should be generated, is it feasible processing for local CPU,
especially in high-speed link (ex. 10GE)?
• It can be applicable for small or medium networks if we are targeting
the enterprise, campus and small datacenter etc.
• Moreover, a solution is proposed that minimize the frame generation.
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Path recovery (cont’d)
a
a
2
1
1 SW3
2
SW5
flush message is terminated
because “b” is not binded to port1
MAC=a
3
3
a
1
a
1
b
2
SW1
flush “b”
b
2
SW2
Delete entry “b” from FDB and re-sends
the flush message to SW1.
a
1
flush “b”
b
2
SW4
a
1
b
2
SW6
MAC=b
May includes two or more…ex. 100s of
MAC addresses to be flushed as a list.
 When link failure is detected, MAC flush lists (187 MAC / 1500B
frame) are flooded. 54 frames by a day for 10K MAC entry.
 Avoid unnecessary flooding, MAC list is deleted to shorten.
 Issues: How to prevent flush frame loss.
May require CPU processing power.
 Experience: 15ms to flush 10K MACs in a node (1GHz MIPS Core)
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Issue2. Server Edge
• Question: If a server has two or more NICs, how to find which
port is first?
• vswitch: only vswitch to support All-Path
• VEB: both VEB and vswitch to support All-Path
• VEPA: only external switch to support All-Path
Vswitch
NIC
NIC
Vswitch
VEB
NIC
VEB
NIC
VEPA
NIC
Ext. switch
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Issue3. Load Balance
• Load balance is available in natural way because high
load link tend not to be selected with queuing delay.
• Pros: zero-configuration load balance, no extra
processing effort
• Cons: you cannot control load balance like SPB/ECMP
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Report on Proposal for AVB TG
• May 12, Thu, morning session @ AVB
• Dr. Ibanez presented the materials as used in IW session
(Singapore and Santa Fe)
• Questions and comments
–
–
–
–
Any other metric than latency e.g. bandwidth?
Path recovery time comparing with RSTP?
Any broadcast storm occurred when link failed?
What’s the status in IW session, any PAR created?
• AVB status
– They try to solve by their own way, using SRP.
– Not only latency but also bandwidth can be used as metric
– Also redundant path can be calculated
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