Filtering Tagged E2 Routes

[bn1st]

Hi guys,Im currently implementing an ospf network with cisco and fortinet. I tagged the e2 routes coming from redistributed eigrp routes from cisco. In fortinet, i already created a route-map with set match-tag. However Im having difficulties finding ways on how to apply the route-map in the ospf process. Both "set distribute-list" and "config distribute-list-in" only give me acl and prefix list options. Hope someone can shed some light. Thanks in advance.

[emnoc]

This comes up like a thousand times, some claim you can't drop E2 prefixes but that's 100% incorrectly. I will show you;

I want to drop one prefix so I craft a prefix-list.

i guess you can use an acl list but I like prefix-list and they are so much easier for ipv4 and ipv6

config router prefix-list     edit "dropit"             config rule                 edit 1                     set action deny                     set prefix 10.212.134.0 255.255.255.0                     unset ge                     unset le                 next                 edit 2                     set prefix 0.0.0.0 0.0.0.0                     unset ge                     set le 32                 next             end     next end

Now we apply this into the router ospf general. The rule #1 match will talke place b4  rule #2 which is basically an "any" prefix

    set router-id 192.0.2.2     set distribute-list-in "dropit"         config area             edit 0.0.0.0             next         end         config ospf-interface             edit "root2custA1"                 set interface "root2custA1"                 set network-type point-to-point             next         end         config network             edit 1                 set prefix 192.168.10.0 255.255.255.252             next         end         config redistribute "connected"         end         config redistribute "static"         end         config redistribute "rip"         end         config redistribute "bgp"         end         config redistribute "isis"         end end

Keep in mind the ospf database will still have the LSA for the network. Here's a screenshot of the before after and ospf database

I hope this helps .

ken

[bn1st]

Hi Ken, Thanks for the input. However, im trying to filter by matching the tags and not by prefix. The prefixes im trying to filter are coming from 2 different sources, (the topology i have is quite complicated) but for simplicity let's just say prefixes are coming from router A and B. I know that filtering is done in the RIB while LSAs are still retained in the ospf database. Please do note that my current ospf database has the LSAs both from router A and B. Prefixes from router B are already tagged. Doing a prefix list, like what you have demonstarted, will drop the RIB entries both from A and B.

[emnoc]

hmm, You can look a  route-map but that's typically used on the source(s)   "route distribution or redistribution" If you need to filter on let's router-id rtr1and not rtrb, can't you have the router 1.0.0.1 manipulate the E2 metrics directly to accomplish what you want ?

Other action could be a summary from that routerA and use the more specific route from routerB.

Bottom line, you should control the route create and distribution at the source. It would make it way much easier.

[bn1st]

Yeah, that's the only place I see where I can apply the route map. I'm trying to filter in the downstream router though.