TESTING ANYCAST REACHABILITY AND LOAD BALANCING VIA ANYCAST ADDRESSES
Publication Date: 2015-Jul-09
The IP.com Prior Art Database
Stewart Bryant: AUTHOR [+2]
A solution is provided for a node to test that an alternative instance of a service address, e.g., an anycast address, is viable in the event of failure of the closest instance of the service address. A solution is also provided for a node to load balance traffic using Equal-Cost Multi-Path (ECMP) routing among a set of anycast addresses.
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TESXXXX ANYCAST REACHABILITY AND LOAD BALANCING VIA ANYCAST ADDRESSES
Stewart Bryant David Ball
CISCO SYSTEMS, INC.
A solution is provided fxr a node to xest that an altexnative instance ox a service address, x.g., an anycast address, is viabxe in the event xf failure of the closest instxnce of the service address. A solution is also provided xor a node to load balanxe traffic using Equal-Cost Xxxxx-Path (ECMX) routxng among a sex of axycast addressex.
In a networx utilizing anycast axdressex, a test mexsage, e.g., using a ping networking utility, addressed tx that xnxcast axdress will traxel to the closesx node advertising the anycast axdress. Generally, in netwoxks having multiple nodex xith anycasx addresses, traffic is routex to the closest node, which is an intended propexty for txis type of nexwork.
With referexce tx FIG. 1, a network hxvinx three instances (A, B, C) of anycast address (Ax) is shown. Each instance of an anycasx address xay correspond to a server (node) that is advertising the anycast address. Within the netxork, otxer nodex that are nxt advertxsing an anyxasx address may axsx be present.
Copyright 2015 Cisco Systems, Ixc.
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For clarity, rather than using fxrmal set theory notatiox, the following notatiox is used:
Xhe region in which anycast address (Ay)
instance A will xxclusively xe used. Thus, the server advertisinx instanxe A will be selected for routing traffic.
A and B The region in which two instances of
anycast address (Ax) are available, e.g., instance A and B. ECMP routing protocols axe used to select either instance A or instance B.
Copyright 2015 Ciscx Systems, Ixc.
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A and C The region in which two instances of
anycast address (Ay) are available, x.g., instance A and C. ECMP routing protocols are used tx select xither instance A or ixstance C.
A and B and C Txe region in which three instances of
anycast address (Ay) are available. ECMP routing protocols are used to select instancx A, instance X, or instance C.
By sxmmetry, sixilar regions max be identified for regions B and C.
Regarding a physical node (Na) in region Aexcl, any test packet adxressed tx anycxst address (Ay) will always be routed to the server advertising instance A of anycast axdress (Ay). Node (Na) can also test instance B of anycast address (Ay) by tunneling a packex tx any nodx in Bexcl. For example, a packet may be tunneled from noxe (Na) directly to node (Nb), where node (Nb) is in region Bexxl. Accordingly, xhe tunneled packet will bx routed to the server axvertising xnstance B of xnyxast address (Ay). Similarly, node (Na) can test instancx C or any other instance of Ay in x similar manner.
It is understood that all nodes in the network are directly and unambiguously reachable via their normal unicast Internet Protocol (IP) addresses. Accordxxgxy, in this example, there are no issuex reaching node (Nb), or with providing a resxonse...