Questions tagged [bgp]

BGP is Border Gateway Protocol, used on the internet both inside of and in between networks.

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Use ECMP to distribute traffic between two paths, one learned by eBGP and one learned by iBGP on a Cisco NX-OS switch

I maintain two cross-connected switches, R1 and R2, which both have a link to an external switch, R3. R1 and R2 both use eBGP to receive routes to various subnets behind R3. Additionally, R1 and R2 ...
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BGP - Active\Passive Setup, except one AS

I have two transit providers, A and B. The business has chosen to make provider A more attractive due to billing concerns (we get attractive bulk pricing from this global provider). This was done by ...
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EVPN/VxLAN border-leaf question

I have couple of question in above design where i have typical clos network design and my leafs are configured for Cisco vPC for redendency and anycast gateway and running OSPF for underlay and BGP ...
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Two Datacenter location with same BGP AS number

Currently we have DC-1 running eBGP with my ISP using AS:1111 and i have prefix 1.1.1.0/24 and using BGP Default route because we have only single ISP. Now we are opening new Datacenter in remote ...
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Can a leaf (mc-lag switch pair) connect to an uplink (spine : a single switch) using lag (not a route-only-port)?

By 'lag', I mean one port from each mc-lag peer connects to a port each on the uplink switch (consider this a single switch spine). The mc-lag is an active-active forwarding pair for L2 traffic (aruba'...
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BGP influence outbound traffic based on prefix

I have two router core1 and core2 connected with ISP router border1 and border2 using eBGP peer and i have 5 public subnect (/24). My ISP sending me default route instead of full BGP table. Question:...
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BGP Community Policy to only allow single Community tagged routes

I have a requirement to do a Cisco IOS-XR Route-policy to allow only routes that have a single community tagged and not allow routes with multiple community tags. I built a lab that has two routes: ...
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Advertising your prefix out of another ASN

We own a few blocks of IP addresses. At several distinct sites we currently advertise our own prefixes on our routers to our upstream transit provider. We are not anycasting. One /24 is originated ...
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Can people with an ISP access your network if it is on the Default Free Zone?

Let's say you have a router on the DFZ (despite costing an absurd ammount of money). Would your network work the same as if you have an ISP in terms of web hosting, etc? Can people still access your ...
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exabgp heathcheck session bgp

I've been trying to use exabgp. I know how to to issue command to the exabgp however i struggle to find whole list of commands the application accepts. With that I can't find a way to receive ...
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Brocade L2VPN Route Reflector

I am trying to create an MPLS VPLS network where the VPLS instances are auto-discovered via BGP L2VPN. The issue I'm currently facing is that the routes are not reflected and there seems to be no ...
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How can I tell which prefixes are being advertised?

Forgive me if this is a dumb question but I'm relatively new to the carrier networking world. We own a block of IP addresses, say a /18 and we advertise various /20s, /24s, /23s, etc all over the ...
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BGP Route Reflector

In the following configuration, INTERNAL1 and INTERNAL4 are RR and INTERNAL2 and INTERNAL3 are clients. I am not able to see the routes 20.1.1.0 and 10.1.1.0 on INTERNAL3 and 30.1.1.0 and 40.1.1.0 on ...
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In Bgp TTL security all control packets will have configured hop value?

Topology: loop(2.1.1.1) - routerA (192.168.1.2)--------- (192.168.1.1) routerB - loop(1.1.1.1) I have eBGP peering configured with a Multihop of 2 on both sides and static routes to reach loopbacks. ...
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isis redistribute bgp not working

I am having trouble getting route redistribution into ISIS working. It works from ISIS to BGP, but I can't get the opposite to show up. I am using IOS-XR Network has 3 routers: A----B----C A and B ...
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Extract upstream/downstream ASNs from BGP table path

I want to extract upstream and downstream ASN for any given ASN, for example: https://www.cidr-report.org/cgi-bin/as-report?as=AS4826&view=2.0 My goal at the end is to generate ASN route graphic ...
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eBGP failover without packet drops

I have core1 and core2 router peer with same ISP but distinct hardware and they are sending us default route. currently all in/out traffic going over to core1 and core2 is idle (standby), I have iBGP ...
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Get ASN Upstreams/Downstreams/Peers

I'm trying to gather the Upstreams/Downstreams/Peers of an ASN. Lets take for example AS8866, I run this query on the ripe API https://stat.ripe.net/data/asn-neighbours/data.json?resource=AS8866 ...
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Routing daemon vs router configuration

Which is the difference between a routing daemon and a router configuration? For example using BIRD you can set up a BPG session, but you can always set up a BGP session for example using a CISCO ...
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Active\Passive Routers w\ BGP

What I'm trying to do is take two routers, "A" and "B" where 'A' is the primary router. Just like with active\passive firewalls and HSRP I want to "float" the default gateway between either Router A ...
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Can BGP-LS provide an ip address as a node attribute when distributing IS-IS

I have an IS-IS network (all cisco) with a BGP router (cisco) that I am using to distribute the network link-state for monitoring / analysis. one thing I would like is to receive an IP address for ...
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Junos: how to change BGP MED for secondary node?

I have vSRX cluster, which announce some protected addresses over IBGP. Each node has two sessions with two routers. (I use ge-0/0/1 and ge-7/0/1 for that). I found that if fail-over happens, and ...
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Why isn't iBGP peer announcing external route it learned to its only peer?

I'm using VyOS to create a BGP lab. It has 6 routers, each in an iBGP pair, and 3 autonomous systems. Routers 1 & 2 - AS1111 Routers 3 & 4 - AS2222 Routers 5 & 6 - AS3333 All routers are ...
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Differences between BGP(routing protocols) and vpn mpls?

I am new to networking, so bear with me, 1-I wanted to clear my query: why do we need BGP or any routing protocols if we have vpn or wan technologies like mpls ? 2-Can't we just run bgp between two ...
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How can I use standard communities for route leaking?

I have a network something like this: R1_____Edge1____BB____Edge2_____R2 \____R3 R1: VRF BLUE (10:10) R2: VRF BLUE (10:10) R3: VRF RED (10:20) Edge1 and Edge2 has both ...
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Is it possible to determine the origin of a BGP withdraw message?

is it possible for an ASN in the BGP path to determine what ASN has been the originator and the cause of withdraw message?
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Why doesn't BGP come up when no hold-time is defined? [closed]

Why doesn't BGP come up when no hold-time is defined? if defined, the BGP protocol comes up without any problem.
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Unexpected bytes in AS_PATH BGP attribute

I am parsing out the ASNs from several AS_PATHS. A majority of the attributes I encounter look like this one: [64, 1, 1, 0, 64, 2, 10, 2, 2, 0, 0, 23, 169, 0, 0, 50, 156, 64, 3, 4, 200, 40, 162, 202]...
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How is the MD5 hash calculated in BGP?

The RFC is very superficial on the implementation details. What is the injective function being used? https://tools.ietf.org/html/rfc2385 MD5 digest is produced by applying the MD5 algorithm to ...
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Difference between step 3 and step 5 of BGP route selection process?

Step 3: Locally injected routes (Locally injected is better than iBGP/ eBGP learned) Step 5: Origin Prefer I over E. Prefer E over ? I went through lot of articles on the internet but not able ...
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Traveling Salesman Problem (TSP) applied to network routing protocols? [closed]

Is this very common for larger enterprises that have many thousands of servers to use something like ant colony or similar algorithms to work together with network routing protocols like BGP to solve ...
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EIGRP to BGP to EIGRP

I would like to ask if it is possible to implement eigrp routing sent through bgp? I wanted to route from PC-1 to PC-2 using EIGRP. The connection between all of the three routers are through BGP ...
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Static routes use redistribute command or network command? [duplicate]

Apologies if this has been asked before, but quick question I have a router, actually a L3 switch that is running bgp. This switch has a bunch of static routes that are redistributed into bgp. ...
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Internet Scale Routing Table Size

In the link below, it is said that there are near one million prefixes for IPv4. https://bgp.he.net/report/netstats I want to know that it is a must for ISP routers to cache all these million IPv4 ...
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Single-homed connection to ISP without NAT feature

Is it possible to connect my private network to the ISP router without a Network Address Translator (NAT) feature enabled on my router? As I understand, in a single-homed scenario connection to ISP, ...
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Is there a way to check which routes are matched by a term in a routing map?

I have created a prefix-list and I am using it in a route-map. However, my route-map is not working as I expect it to work. ip prefix-list LIST_A seq 5 permit 10.20.20.0/22 ge 32 route-map A-B-OUT ...
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How to read a BGP table?

I have come across BGP looking glass where I can see the routing table for public routers. Please find below a public entry: BGP routing table entry for 78.97.0.0/16 Versions: Process ...
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BGP rule to avoid given ISP?

Is it possible to have a rule/policy in BGP to avoid a given ISP for the traffic? Ex.: traffic from the USA should touch middle east ISPs if the target/source is not from/to there. I am not sure ...
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What are the current security issues S-BGP has?

The question is explained in full in the title. I wish to know what the security issues are when deploying S-BGP. Thank you in advance!
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What does the BGP protocol consider when determining the best path?

What does BGP protocol consider when determining the best path? Why is it considered the slower than interior routing protocols like RIP, OSPF, etc?
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BGP best path algorithm throttling?

Let's consider a simple scenario: Router R1 in AS100, which has direct connections to routers R2 (AS200), R3 (AS300), R4 (AS400), R5 (AS500). Regular eBGP neighborships are formed over these links. ...
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How is traffic correctly routed in Site-to-Site VPNs where all sites are on the same subnet?

http://rockhoppervpn.sourceforge.net/ref_site2site_bridge_6.html The diagram on this page shows all 3 sites using the same subnet, 192.168.0.0/24. Let's say on the hub site where 192.168.0.10 is the ...
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How TCP connections between origin and node servers over a BGP Anycast gets established?

Server A and B have the same IP address with anycast. Server B connects to the origin server that is very close to server A and very far away from server B, since server A is closer, the response will ...
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Problem in cisco routing bgp routes

We have an outbound route-map on an eBGP peer that adds some communities to certain prefixes. Is there any way to prove that this is actually happening from the sender side in classic IOS? show ip ...
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BGP Collector and Vantage Point relationship

I am currently reading a paper BGPStream: A Software Framework for Live and Historical BGP Data Analysis where authors say: Normally, a BGP session with a collector is configured as a customer-...
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Same /24 IP prefix, same AS for 2 different locations, possible?

Let's say I have 2 locations: 1. the United States Datacenter 2. the Russian Federation Datacenter I have 1 /24 Subnet with 1 AS. Both sites have a different ISP. My target is to: allocate /24 for ...
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BGP and NAT Not working

I have an odd issue with BGP+NAT. I have 2 separate routers and 2 different ISP's. Topology looks like this: ISP1--BGP--> RTR1 \ \--OSPF-- Palo Alto Firewall-- Internal ...
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BGP local-as command clarification

On my network infrastructure, an Arista switch is the core switch and a pfsense server the gateway. BGP is used to advertise routes for all the internal networks. On Arista switch, I see the BGP ...
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How does the BGP UPDATE message propagation work?

I am currently reading about Routing around Congestion Defense and the non feasibility of this approach. Since to use this method a lot of BGP poisoning would be necessary and to switch paths several ...
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Route advertisement and FIB programming

Que1. Assuming bgp is running on a network device, will the route advertisement and FIB programming(basically populating entries in hardware) occur in parallel? Or does it occur sequentially, meaning, ...

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