Questions tagged [bgp]

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

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36 views

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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54 views

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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51 views

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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35 views

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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115 views

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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69 views

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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62 views

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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35 views

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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60 views

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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55 views

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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High Throughput on BGP Multihomed Network

I've One site connected to my server location via BGP over MPLS and at my server location 2 edge routers cater these WAN links, and are further connected to Servers via switches. Now, Is it possible ...
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What is the difference between connect and active states of BGP?

What is the significance of having two different states in FSM when both try to establish TCP Connection?
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What does a transition from static IP to BGP look like?

We initially got a /30 from our upstream and now we're ready to start running BGP to advertise our own /24. What does that sort of process typically look like? Does it likely require some prior ...
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163 views

How does aggregate routes behave in BGP?

If a router received two BGP updates for the same prefix and both these updates are aggregate paths how do the router decide which one to take? Let us say that it needs to decide based on AS Path ...
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How BGP guarantees same route for a forwarded packet?

In BGP all routers choose the best route to a single destination. So for Router A and destination D, A will forward the packet to the next-hop router (let us say router R) after knowing the best route ...
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Troubleshooting connectivity in BGP/Quagga/Docker lab

I have created a virtual networking lab to test BGP routing. The lab is made up of two Debian Docker images which serve as end users and two images running Alpine Linux with Quagga to serve as the ...
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Ho to implement RPKI for our Network

I would want to implement RPKI in my network. I have gone through some documents by which i cant understand the implementation process. What are the steps i should follow to implement RPKI in my ...
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150 views

How to bypass when network speed over a special number in Juniper?

I have a requirement, such as I have 113.100.15.0/24 segment IP addresses. in Juniper M480 Router I connected to BGP-A(1G) and BGP-B(10G), by default the 113.100.15.0/24 out the Router it go ...
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Why do IXPs need ASN?

Does anybody know why an IXP needs to have an ASN? Will that ASN appear in the AS-PATHs or will it be transparent?
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Method to rename the existing BGP peer group

In Cisco ASR router, do we have any method to rename the existing peer group without removing and recreating it?
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149 views

Reasons for buying ASN for organisation that are located at single place

I see here that even some organisation/universities have bought ASN which are located at single location. What benefit they will get by buying ASN ? Is it compulsory to buy ASN if I have to buy some ...
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What is benefit of allocating ASN to edge routers and not Ip addresses

What is benefit of allocating ASN to edge routers and not Ip addresses ? I mean we could have given these edge routers unique public ip addresses too ?
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Global BGP Routing only by only importing supernet prefixes

I was wondering if global IPv4 Routing can be technically achieved only by importing from the ISP Provider (providing us with a IPv4 BGP full table) a subset from the BGPv4 routes (i.e. all prefixes ...
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In case if BGP connected to two peers then how Graceful restart capability advertised in open message

As per RFC 4724 "A BGP speaker MUST NOT include more than one instance of the Graceful Restart Capability in the capability advertisement [BGP-CAP]. If more than one instance of the Graceful ...
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can some one explain BGP router graceful restart flow?

can some one please explain BGP router graceful restart flow , how the messages will exchange before restart and after session re-establish between BGP router and it's peer.
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Understanding MP-BGP IPv4 AFI

I was writing my own BGP speaker, and I am a bit confused by the IPv4 AFI of MP-BGP. I understand that to exchange IPv6 routing information peers need to agree on it by sending the MP-BGP capability ...
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Why is bgp used for AWS and gcp VPNs and not another routing protocol? [closed]

I use AWS and gcp. Both of these cloud platforms have the ability to establish a VPN connection from a VPC in the cloud to an on-premise router or another cloud VPN endpoint. They both use bgp ( and ...
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31 views

bgp filtering based on conjunction of prefix-list and as-path originator

Is there any way of having a filter that uses as-path origin and prefix-list together. For example I want to accept updates from origin of AS 5745 and prefix-list is say 189.150.20.X/24. Any other ...
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What is the use of route-target without export/import?

On my router, I can configure the following: I canont find any information regarding the use of the "route-target ASN:nn" command. I know what route-target import/export allows me to do, but what use ...
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Regarding Administrative Distance

Different vendors use different Administrative distance for the same protocol.For example, in a Cisco router, the eBGP, AD value is 20, whereas in Arista routers, it appears different(i believe, 200). ...
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971 views

Does anycast addressing add additional latency in any way?

Does anycast addressing, in itself, add any additional latency to network connections? Specifically, if you had two servers located in the same data center that had extremely similar routes/number of ...
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BGP | Advertise a summary prefix out to customer location

I don't know what I should be using for this or how I should go about it. In my lab where I am testing out the BGP configs that I've learned I want my ISP topology to have a summary prefix for the ...

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