Change Uplink By community Tag

[admin@atrinnet.net]

HI Dears Customer Announce to me Prefix X.X.X.X/24 if without tag announce upnllink 1 if customer used tag 200:200

in route-map that assign bgp uplink 1 deny tag 200:200 in ASR add

ip bgp-community new-format

show ip bgp X.X.X.X/24
BGP routing table entry for 87.107.111.0/24, version 74678
Paths: (1 available, best #1, table default)
Advertised to update-groups:
2 9 13
Refresh Epoch 1
208555 208555 51026, (received & used)
172.18.22.26 from 172.18.22.26 (172.19.19.1)
Origin IGP, localpref 100, valid, external, best
Community: 13107400
rx pathid: 0, tx pathid: 0x0
Updated on Oct 22 2024 16:57:45 UTC

show ip bgp X.X.X.X/24
BGP routing table information for VRF default, address family IPv4 Unicast
BGP routing table entry for 87.107.111.0/24, version 2092
Paths: (2 available, best #1)
Flags: (0x8000001a) (high32 00000000) on xmit-list, is in urib, is best urib rou
te, is in HW

Advertised path-id 1
Path type: internal, path is valid, is best path, no labeled nexthop, in rib
AS-Path: 208555 208555 51026 , path sourced external to AS
172.18.14.254 (metric 0) from 172.18.14.254 (185.217.6.66)
Origin IGP, MED 0, localpref 800, weight 0
Community: 200:200

Path type: internal, path is valid, received only, no labeled nexthop, is extd
AS-Path: 208555 208555 51026 , path sourced external to AS
172.18.14.254 (metric 0) from 172.18.14.254 (185.217.6.66)
Origin IGP, MED 0, localpref 100, weight 0
Community: 200:200

and this community see but in nexus 9K announce to uplink1 and uplink 2

[balaji.bandi]

what are you trying to achieve with the TAG, does your provide accept that do something with that ?

if not then use normal network announcements.

[admin@atrinnet.net]

On nexus 9K define route-map on uplink1 and

route-map uplink-1 deny 1

macth community 200:200

end of rule

But

Donnot work also announe on uplink-1 prefix X.X.X.X/24 by community tag 200:200

[balaji.bandi]

Not sure any Limitation on nexus need to check the documentation : generally i do as below not send community

May be try - check before you apply the commands.

ip prefix-list MYLIST permit X.X.X.X/24

route-map MYLIST permit 10
match ip addr prefix MYLIST
set community no-export

route-map MYLIST permit 20

router bgp BBBB

neigh y.y.y.y send-community
neigh y.y.y.y route-map MYLIST out

[admin@atrinnet.net]

Donnot used deny rules if community 200:200 set bgp community no-export-only and used accept rules ????

[admin@atrinnet.net]

Used this

route-map respina, permit, sequence 6
Match clauses:
community (community-list filter): 200:200
Set clauses:
community no-export

By uplink see my prefix by community 200:200

my nexus version is

NXOS image file is: bootflash:///nxos64-cs.10.3.5.M.bin

[balaji.bandi]

not that i have tested nexus need to test in Lab, may be over weekend let me test if i get chance.

[admin@atrinnet.net]

Thanks i am waiting

[balaji.bandi]

I have made typo that should be deny and tested and it works.

On the nexus :

ip prefix-list MYLIST seq 5 permit 20.20.20.0/24
route-map MYLIST deny 10
match ip address prefix-list MYLIST
set community no-export
route-map MYLIST permit 20

router bgp 100
address-family ipv4 unicast
neighbor 10.10.5.1
remote-as 300
update-source Ethernet1/2
address-family ipv4 unicast
send-community
send-community extended
route-map MYLIST out
neighbor 10.10.6.1
remote-as 400
update-source Ethernet1/3
address-family ipv4 unicast
neighbor 10.10.10.2
remote-as 200
update-source Ethernet1/1
address-family ipv4 unicast

This works for me i can not see the routes of 20.20.20.0/24 on the neighbor 10.10.5.1

[paul driver]

Hello
TBH not so sure what your trying to achieve, however it seem your trying so send a prefix towards a bgp peer and for that peer then not to re-advertise onwards based on community attribute of NO-EXPORT if so,  then that receiving rtr MUST also send community upstream otherwise the attribute will be stripped from the prefix and advertised normally

example
ASR
router bgp xxx
neighbour <9K>  send-community

9k
router bgp xxx
neighbour <uplink1>  send-community
neighbour <uplink2>  send-community

[admin@atrinnet.net]

Enable send community in  address-family but my problem is community- Not change or prefix disacrd