Specifications

OmniAccess 5510 USG - Release Notes
September 2010
OSPF
OSPF is an IGP (Interior Gateway Protocol) developed by the OSPF working group of the IETF
(Internet Engineering Task Force). OSPF was designed expressly for the IP networks. OSPF supports
IP subnetting and tagging of externally derived routing information. Packet authentication and
sending and receiving packets using IP multicast are also supported in OSPF.
Using OSPF, a host that obtains a change to a routing table or detects a change in the network
immediately multicasts the information to all other hosts in the network so that all will have the same
routing table information. The host using OSPF sends only the part that has changed. OSPF multicasts
the updated information only when a change has taken place.
Instead of counting the number of hops, OSPF bases its path descriptions on "link states" that take
into account additional network information. OSPF also lets the user assign cost metrics to a given
host router so that some paths are given preference. OSPF supports a variable network subnet mask so
that a network can be subdivided.
BGP
BGP is an inter-Autonomous System routing protocol. The primary function for a BGP speaking
system is to exchange network reachability information (NLRI) with other BGP systems. This
network reachability information includes information on the list of Autonomous Systems (ASs). This
is sufficient to construct a graph of AS connectivity from which routing loops may be pruned and
some policy decisions at the AS level may be enforced.
BGP neighbors form a TCP connection between one another. They exchange messages to open and
confirm the connection parameters.
Policy Based Routing
Branch offices need the freedom to implement packet forwarding and routing according to their own
defined policies in a way that goes beyond traditional forwarding and routing algorithms. PBR is
useful in deployments, where administrative issues dictate that traffic be routed through specific
paths. By using PBR, customers can implement policies that selectively cause packets to take
different paths.
PBR provides the ability to route traffic based on attributes other than the destination IP address.
Attributes like source IP address, protocol type can be used to define policies and apply them to an
interface.
VRRP
VRRP allows routers on a LAN to back up a static default route with a virtual router. VRRP
dynamically assigns responsibility for a virtual router to a physical router (VRRP router) on the LAN.
The virtual router is associated with an IP address (or set of IP addresses) on the LAN. A virtual
router master is elected to forward packets for the virtual router’s IP address. If the master router
becomes unavailable, the highest priority backup router will transition to the master state.
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