Y'all made me curious, and as Steve mentioned, this "tag" and "tag2" option apparently, with BGP, is locally significant only. I'm wondering if Juniper allows it to some how propagate outside of the router when used in an OSPF or IS-IS policy as I read that it sets something in External LSA's or TLV's (respectively)... but of course your topic is bgp-related.
I read here that it is in fact, used with BGP on import policy direction only, and is a 2^32 number... I'm thinking, when tags are set, they are then later used as influencers into what the local bgp table decides.
https://www.juniper.net/documentation/partners/ibm/junos11.4-oemlitedocs/config-guide-routing-policy.pdf
p.s. i could see where the confusion may come with bgp community "tags" since when searching through docs the word "tag" is used to describe a bgp community... so I wish they would've simple called it just that.... a bgp community attribute, so as not to confuse one with the other :)
------------------------------
Aaron Gould
Senior Network Engineer
aaron@gvtc.comhttps://www.linkedin.com/in/agould123/------------------------------
Original Message:
Sent: 05-18-2021 17:12
From: STEVE PULUKA
Subject: question about bgp route tag
I don't use tags but believe they are local use only.
We use communities to add an attribute to a route that will then be shared to other neighbors that we send that route to.
------------------------------
Steve Puluka BSEET - Juniper Ambassador
IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
http://puluka.com/home
Original Message:
Sent: 05-18-2021 14:24
From: Unknown User
Subject: question about bgp route tag
I have the following topology
I have the following configuration on vMX2 to tag 1.1.1.1 learnt from vMX1
vMX2set policy-options policy-statement AddTag term 1 from protocol bgpset policy-options policy-statement AddTag term 1 from externalset policy-options policy-statement AddTag term 1 from route-filter 1.1.1.1/32 exactset policy-options policy-statement AddTag term 1 then tag 510set policy-options policy-statement AddTag term 1 then acceptset protocols bgp group TovMX1 import AddTagroot@vMX2# run show route 1.1.1.1 extensive | match Tag Tag: 510
Is this tag supposed to be carried to vMX3 and vMX4 ?
I could not see the tag on vMX3 and vMX4.
Did I miss something here ?
thanks !!