MP BGP Redistribute

[SajeshB]

Need help to understand what does Redistribute static and redistribute connected do under address-family ipv4 vrf Vrf_name

Does Redistribute static will leak the route from global routing table into vrf routing table and Redistribute connected can do Intervlan routing between SVI Vrf Vlan and non SVI vrf vlan or 2 different Vrf Vlan can communicate with each other.

[paul driver]

Hello
No it wont.
By default  It will only redistribute static routes and connected routes to others that exist under that particular vrf.

[SajeshB]

If it will Redistribute the statc and connected route of that particular vrf. But this my device will learn anyway this route without Redistributing it because they are on same vrf correct me if im wrong.

Like if i i have 2 Vlan : Vlan 10 and Vlan 20 having different subnets but in same vrf without Redistribute connected i can ping Vlan 10 and 20 as they are in same vrf so why this is required and for static route i didnt get it what you written but for this vrf there will be a single routing table so using Redistribute static where it will do redistribute ?? in which vrf??

Is there any cisco doc's you can help me with pls.

[Jon Marshall]

A VRF is just another routing table so if those connected and static routes are on one device and you want another device in the same VRF to know about them then you would need to redistribute those routes. 

If you don't redistribute them only the device those routes are on will know about them. 

Jon

[Giuseppe Larosa]

Hello Sajesh,

the purpose of redistrubution of connected routes and static routes in address-family ipv4 vrf <vrf-name> is to create the corresponding VPNv4 prefixes by:

prepending the 64 bit Route Distinguisher configured in the VRF to the 32 bit IPv4 prefix, setting the next-hop attribute = local PE backbone loopback address and adding as extended comunity the route target(s) ( one or more then one).

(Also an MPLS label is associated to the VPNv4 prefix and it is called the VPN label it is used in the forwarding plane)

This is called exporting to the backbone

In this way remote PE routers can receive the VPNv4 prefixes created by source PE and they can import the corresponding IPv4 prefixes in one or more locally defined VRFs if they can import one of the route-targets values associated to each VPNv4 prefix.

This phase is called importing from the backbone.

The same applies if an IGP in use in the VRF with a CE node  like OSPF or EIGRP with some addtional possible features that may allow emulation of an OSPF domain or an EIGRP domain.

Communication between PE nodes happen in AF VPNv4 , address family ipv4 vrf <vrf-name> is directed to CE node(s) and it is used to receive local routes either by eBGP or by simple redistribute connecte and redistribute static. In the other direction the local PE will send to a CE either a default route or the details of all the routes of all the sites that take part in the same VPN.

An MPLS L3 VPN is a collection of VRF sites that share the same route-targets values.

Hope to help

Giuseppe

[balaji.bandi]

Redistribute connected   - It will redistribute the connected physical and/or logical interfaces for that specific router you are doing the redistribution.

Redistribute static - it will redistribute static routes or default routes to the routing protocol.

example  guide :

https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/8606-redist.html

If you looking to route leak on VRF environment

you need to route VRF based static router to GTR. and vice versa, by default it will not.

in MP BGP you need to configure same in address-family config to redistribute.

[SajeshB]

I know how both the Redistribute work but in MPBGP im just confused

[MHM Cisco World]

Friend 

mp-bgp is used to connect to CE,

the protocol between CE-PE can be 

ospf ebgp ...

or 

we use Static route to all prefix behind the CE and here “redistribute Static”

now this Static route have next hop which is direct connect to PE vrf and here we need “redistribute connected”