2. The AMS-IX Topology
The AMS-IX network is built as a redundant hub & spoke topology using Glimmerglass photonic cross-connects and Foundry Networks switches. A hub & spoke topology has one core switch and multiple access switches connected to it (see figure below).
Naturally the core and each connection between access and core switch are a single point of failure. Therefore AMS-IX implemented a redundant hub & spoke topology (see figure below) which is built around two sets of core switches: one at Global Switch and one at EUNetworks. Only one set of switches is active at a time (either red or blue connections) and it allows us to swap between the topologies in case of a maintenance or failure on one of the sides.
Customers up to 1GE are directly connected to Foundry Networks edge switches, available at each location. One can connect with 100Mb via UTP or 1GE via multimode or singlemode fiber. Fiber connections are supported using SX or LX optics, and in some cases also LH-A or LH-B.
10GE customers connect to the AMS-IX platform via Glimmerglass photonic cross-connects, Layer 1 switches. Those Layer 1 switches connect the customer to one of the two available Ethernet switches, which one in particular depends on the at that time active part of the topology. The 10G Ethernet access switches are locally available at each location and one can connect with either ER or LR optics.
2.1. General 10GE Specifics
A photonic switch introduces less than 3 dB of attenuation between the AMS-IX patch panel and the Ethernet access switch. A switchover between the two topologies introduces a very short link flap (typically < 20 ms). In order to avoid BGP instability, you should configure your router to ignore such events.
Most vendors implement specific commands to ensure BGP ignores such events (see "10GE specifics" in the respective vendor sections for Cisco, Force10, Foundry and Juniper configurations). If your router platform does not support such a feature, we advise you to configure the equivalent of:
no bgp fast-external-fallover |
to ignore link flaps and wait for the BGP hold timers to expire before resetting sessions.