Layer 2
Use a switch to interconnect ISPs
Layer 2
Layer 2 with router reflector
Layer 2 with route server
Layer 3
Use a router to interconnect ISPs
Selection of architecture
Layer 2 preferred
More autonomy to ISPs
No much processing in layer 2
The switch will not be bottleneck
Low cost
Simple for administration
Considered alternatives
Alternative A
Layer 2 with route reflector
Two switches for redundancy
Two route reflectors for redundancy
Alternative B
Layer 2
Two switches for redundancy
Alternative A - topology
Alternative A – some issues
The IXP is an AS( public ASN)
Public IP addresses used
BGP4 used
ISPs may/may not collocate their routers
Transit for IXP services
The IXP gets transit from one or more ISPs
Alternative A - transit using IGP
Alternative A - transit using IBGP
Alternative A - transit using private connection
Which transit method to use?
IGP
Not suitable for transit via multiple ISPs
Additional administrative overhead
IBGP
Suitable for transit via multiple ISPs
Private connection
Needs additional physical setup
Not suitable for transit via multiple ISPs
IBGP preferred
Alternative B - Topology
Alternative B
Alternative B – some issues
The IXP is one AS (public ASN)
Public IP addresses used
BGP4 used
Full mesh peering between ISPs
IXP peers with the transit ISP(s)
Alternative B - transit
Favorite topology
Favorite Topology
Equipment - selection
Switch
Should have Gigabit Ethernet ports
Should have sufficient ports
Cost
Technical support
Router
Cost
Technical Support
Ipv6 support
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