I would like to know how eigrp and rip used address-family. My understand of the utilisation of address-family in BGP is that the routing control plane used BGP communitiies to indicate traffic classes and update associated topologies. I think that this means the BGP carries the RD or RT (do not know which one) to identify to which VRF belongs the announce route. Please correct me if I am wrong.
I would like to understand if eigrp or RIP carries similar information with their route of VRF is only provides local significance on the router.
Finally, I would like to know if the address-family concept applies to OSPF.
a BGP VPNv4 prefix is made by RD:IPv4 with extended community RT (at least one but multiple are possible)
so both are present with RD being part of 96 bit VPNv4 address
EIGRP and RIP uses address-family in order to provide support for VRF PE-CE protocol: the idea is that of creating a small sub database that is VRF specific. The routing messages sent out and received on PE-CE link are regular IPv4 updates and only PE node is aware of the VRF existance.
In order to make the routes known in the backbone (export phase) you need to redistribute the PE-CE IGP into BGP in the appropriate address family (address family ipv4 vrf )
Without doing this the VPNv4 routes are not created and the routes learned by CE are not available on remote PE nodes.
In the same way to pass remote VRF sites routes to the local CE using EIGRP/RIP/OSPF you need to redistribute BGP ( implies same address family ipv4 vrf into the PE-CE IGP routing protocol or if the design allows this, to generate a default route.
First implementantions of OSPF as PE-CE required a dedicated OSPF process for each VRF meaning a clear scalabilty limit.
later implementations have been able to avoid to count these processes under the box limit but I think they still use process + vrf name in process creation they just remove that limit.
the reason for the missing of address family in OSPF comes from its specifications that provide closed data structures, it is the same reason a new version of OSPF ( OSPFv3) has been introduced for IPv6
RIP and EIGRP probably allows for an internal tag to be added to type length value data structures so the capability to introduce address families.
Can you please tell me if BGP running only ipv4 only is like RIP/EIGRP where the vrf is only used locally to separate route belonging to different VRF.Does these BGP packets carries something different than regular BGP.
I have taken the address-family ipv4 configuration from the following link:
BGP is used to transport the OSPF customer VRF route from CE-1 (AS-800) to PE (AS-100). The example does not show how router are transport from PE to CE-2. I assume it is done by running another BGP session from PE (AS-100) to CE-2 (AS-400) but I am not sure. If this configuration is like any standard BGP with a local VRF context, I would assume that BGP could been replaced by EIGRP or RIP.
The fact is that you cant replace BGP with any other routing protocol because its a Multi Protocol BGP. The Multi Protocol BGP allows to carry Labeled IPv4 packets , Labeled IPv6 Packets, VRF, Multicast and Unicast. The Labeled Packets cant be carried out by other routing protocol, Its Only BGP have this capability.
The RT (Route-target) which is extended BGP community attribute is carried out through VPNv4 or vpnv6 sessions and it cant be also carried out by another routing protocol.
If I have correctly understand these answers. The BGP define under address-family ipv4 uses Network Layer Reachability (NLRI) composed of a standard IPv4 address associated with it`s mask. It can exchange route with another BGP peer on a different router that is not defined under an address-family ipv4.
BGP define under address-family vpn4 are using a Network Layer Reachability (NLRI) composed of VPNv4 prefix(RD +IPv4) address,Route Target that carried by the Extended Communities (enabled with neighbor X.X.X.X send community both) and MPLS mux label.
In addition (this is the part where I am not sure), every routes that belongs to the routing procol defined under the address-familly will be redistributed to the neighbor defined under address-family vpn using VPNv4 prefix.
If I have
correctly understand these answers. The BGP define under address-family
ipv4 uses Network Layer Reachability (NLRI) composed of a standard IPv4
address associated with it`s mask. It can exchange route with another
BGP peer on a different router that is not defined under an
Correct. BGP defined within address-family ipv4 is the usual BGP. In fact, this way of configuring BGP is called the AFI model (Address Family Identifier), see this document:
Having some configuration placed in address-family ipv4 is just having a nice "box" for the configuration that was usually placed at the global level of BGP configuration without any address families.
BGP define under
address-family vpn4 are using a Network Layer Reachability (NLRI)
composed of VPNv4 prefix(RD +IPv4) address,Route Target that carried by
the Extended Communities (enabled with neighbor X.X.X.X send community
both) and MPLS mux label.
Correct. As a side remark, note that the BGP is actually the only protocol that runs over and above VRFs. All IGPs run confined inside VRFs and do not see beyond the VRF. The BGP is the only protocol that keeps the overview of all VRFs at once as it is able to preserve their isolation when carrying the routes from the various VRFs.
In addition (this is the part where I am not sure), every routes that
belongs to the routing procol defined under the address-familly will be
redistributed to the neighbor defined under address-family vpn using
Correct. The redistribution from a particular VRF into BGP will be configured in the BGP's address-family ipv4 vrf NAME configuration section and the redistributed routes will be subsequently advertised to neighbors activated under the address-family vpnv4 context.
Introduction: The "external-out enable" command is available for
configuration under the "router ospf process" in case of the IOS-XR
operating system. This command basically enables advertisement of
intra-area routes on the device as external routes in th...
IntroductionIn this article we'll discuss how to troubleshoot packet
loss in the asr9000 and specifically understanding the NP drop counters,
what they mean and what you can do to mitigate them. This document will
be an ongoing effort to improve troublesh...