BGP VPLS Auto Site ID
Bhupesh Kothari ([email protected])
Kireeti Kompella ([email protected])
Thomas Spencer ([email protected])
VPLS Site ID Requirements
• Site IDs configured on each VPLS PE
must be unique per VPLS domain.
– Exception is multi-homing.
• Site IDs must be dense per VPLS
domain.
– Good allocation: 10,11,12,13,50,51,52,53
VPLS Auto Site ID Goals
• Eliminate the need to provision site IDs
• Distributed approach with no central device
(like PE, RR) allocating site IDs for better
scaling and fault tolerance properties
• No extra state on PEs beyond what already
exist today
• Backwards compatibility with current explicit
site ID allocation approach
• Procedures should work when VPLS domain
span multiple AS
VPLS Auto Site ID Approach
• Each PE keeps track of site IDs already in
use and claims an unused ID when it needs
one
• If two PEs claim the same site ID, then they
run a collision resolution algorithm to resolve
the collision in favor of one of the claimants
• Algorithm guarantees convergence: all sites
will ultimately pick unique site IDs
• Simple optimizations make the chance of a
collision extremely small in real life
• Explicitly configured site IDs always win over
dynamically generated ones
Auto Site ID Negotiation
2
4 Real
Claim
5
1
3 Real
5
8
0
1
0
E
8
8
Claim 1
8
0
0
D
a)
b)
c)
d)
Wait to receive NLRIs
Send a claim adv.
Wait for collision
No collision=>send a
real adv.
e) Withdraw claim adv.
A
C
1
1
8
B
6
2
1
8
VE ID
1
Offset
8
Range
BGP VPLS NLRI
VPLS Auto Site Restrictions
• Site IDs need to be explicitly configured
with multi-homing
– PEs cannot tell that they are connected to
the same site and coordinate site ID
allocation
VPLS Auto Site ID
• Details are in:
draft-kothari-l2vpn-auto-site-id-00.txt
• Questions?