HP 6125G HP 6125G & 6125G/XG Blade Switches Layer 3 - IP Routing Confi - Page 282
Static routes, RIP, OSPF, IBGP, Route exchange between an MCE and a PE
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Static routes An MCE can communicate with a site through static routes. As static routes configured for traditional CEs take effect globally, address overlapping between multiple VPNs remains a problem until the emergence of MCE. MCE allows static-route-to-VPN-instance binding, which isolates the static routes of different VPNs. RIP The switch can bind RIP processes to VPN instances. With these bindings on the MCE, private network routes of different VPNs can be exchanged between MCE and sites through different RIP processes, isolating and securing VPN routes. OSPF The switch can bind OSPF processes to VPN instances and isolate the routes of different VPNs. For an OSPF process bound to a VPN instance, the router ID of the public network configured in system view is invalid. You must specify the router ID when creating an OSPF process. An OSPF process can be bound to only one VPN instance. However, a VPN instance can use multiple OSPF processes for private network route transmission. To make sure routes can be advertised properly, configure the same domain ID for all OSPF processes bound to the same VPN instance. Routes redistributed from OSPF to BGP on the MCE have their OSPF attributes removed. To enable BGP to distinguish routes redistributed from different OSPF domains, you must enable the redistributed routes to carry the OSPF domain ID by configuring the domain-id command in OSPF view. The domain ID is added to BGP VPN routes as an extended community attribute. In cases where a VPN has multiple MCE devices attached to it and when an MCE device advertises the routes learned from BGP within the VPN, the routes may be learned by other MCE devices, generating route loops. To prevent route loops, configure route tags for different VPN instances on each MCE. HP recommends that you assign the same route tag to the same VPN on all MCEs. IBGP To use IBGP to exchange private routes between an MCE and a site, configure IBGP peers for VPN instances on the MCE and redistribute IGP routing information from corresponding VPNs. If the MCE is connected with multiple sites in the same VPN, you can configure the MCE as a route reflector (RR) and configure the egress routers of the sites as clients, making the MCE reflect routing information between the sites. This eliminates the necessity for BGP connections between sites, reducing the number of BGP connections and simplifying network configuration. EBGP To use EBGP for exchanging routing information between an MCE and VPN sites, you must configure a BGP peer for each VPN instance on the MCE, and redistribute the IGP routes of each VPN instance on the VPN sites. You also can configure filtering policies to filter the received routes and the routes to be advertised. Route exchange between an MCE and a PE Routing information entries are bound to specific VPN instances on an MCE device, and packets of each VPN instance are forwarded between MCE and PE according to interface. As a result, VPN routing information can be transmitted by performing relatively simple configurations between MCE and PE, such as importing the VPN routing entries on MCE devices to the routing table of the routing protocol running between MCE and PEs. 272