mplsvpn技術(shù)(編輯修改稿)
2025-08-18 09:45 本頁面
【文章內(nèi)容簡介】 ss to make it globally unique ? The resulting 96bit address is called VPNv4 address ? VPNv4 addresses are only exchanged via BGP between PE routers ? BGP supporting other address families than IPv4 addresses is called multiprotocol BGP 169。 2022, Cisco Systems, Inc. Page21 Route Distinguisher Usage in MPLS VPN Pwork PE1 PE2 CustomerA CustomerB CustomerA CustomerB CErouter sends an IPv4 routing update to the PErouter 64bit Route Distinguisher is prepended to the customer IPv4 prefix to make it globally unique, resulting in 96bit VPNv4 prefix 96bit VPNv4 prefix is propagated via BGP to the other PE router 169。 2022, Cisco Systems, Inc. Page22 Route Distinguisher Usage in MPLS VPN Pwork PE1 PE2 CustomerA CustomerB CustomerA CustomerB PE router sends the resulting IPv4 prefix to the CE router Route Distinguisher is removed from the VPNv4 prefix, resulting in 32bit IPv4 prefix 169。 2022, Cisco Systems, Inc. Page23 Route Distinguisher Usage in MPLS VPN ? RD has no special meaning— it is only used to make potentially overlapping IPv4 addresses globally unique ? Simple VPN topologies require one RD per customer ? RD could serve as VPN identifier for simple VPN topologies, but this design could not support all topologies required by the customers 169。 2022, Cisco Systems, Inc. Page24 Route Targets ? Some sites have to participate in more than one VPN— route distinguisher cannot identify participation in VPN ? A different method is needed where a set of identifiers can be attached to a route ? Route Targets were introduced in the MPLS VPN architecture to support plex VPN topologies 169。 2022, Cisco Systems, Inc. Page25 What are Route Targets? ? Route Targets are additional attributes attached to VPNv4 BGP routes to indicate VPN membership ? Extended BGP munities are used to encode these attributes ? Extended munities carry the meaning of the attribute together with its value ? Any number of route targets can be attached to a single route 169。 2022, Cisco Systems, Inc. Page26 How do Route Targets Work? ? Export route targets identifying VPN membership are appended to customer route when it is converted into VPNv4 route ? Each virtual routing table has a set of associated import route targets that select routes to be inserted into the virtual routing table ? Route targets usually identify VPN membership, but can also be used in more plex scenarios 169。 2022, Cisco Systems, Inc. Page27 Impact of Complex VPN Topologies on Virtual Routing Tables ? A virtual routing table in a PE router can only be used for sites with identical connectivity requirements ? Complex VPN topologies require more than one virtual routing table per VPN ? As each virtual routing table requires a distinct RD value, the number of RDs in the MPLS VPN work increases 169。 2022, Cisco Systems, Inc. Page28 MPLS VPN Routing CERouter Perspective ? Customer routers run standard IP routing software and exchange routing updates with the PErouter ?EBGP, OSPF, RIPv2 or static routes are supported ? PErouter appears as another router in the customer’s work MPLS VPN Backbone PErouter CErouter CErouter 169。 2022, Cisco Systems, Inc. Page29 MPLS VPN Routing Overall Customer Perspective ? PErouters appear as core routers connected via a BGP backbone to the customer ? Usual BGP/IGP design rules apply ? Prouters are hidden from the customer Site IGP BGP backbone CErouter PErouter Site IGP Site IGP PErouter 169。 2022, Cisco Systems, Inc. Page30 MPLS VPN Routing PRouter Perspective ? Prouters do not participate in MPLS VPN routing and do not carry VPN routes ? Prouters run backbone IGP with the PErouters and exchange information about global subs (core links and loopbacks) MPLS VPN Backbone Prouter PErouter PErouter 169。 2022, Cisco Syst
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