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

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Using a Public AS Number Internally

We have BGP between our network and our customers networks and so far each connection uses private AS numbers (on our end we use a different AS number for each connection) We recently got a public AS ...
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1answer
33 views

how to select the most optimized BGP Anycast combination with BGP as-path prepending

The question as following: Suppose I have 3 POP (Points of Presence) points, they have the same IP address and located at different countries, such as: USA, Japan, England. The three countries serve ...
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35 views

BGP new subnet announcement

I have above scenario where I got public IP subnet got from ISP 74.100.100.0/23 and i have configured eBGP and iBGP as you can see in diagram, I have configured those Public IP in HSRP my LAN side. ...
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0answers
30 views

mp_reach_nlri bgp Update with 4-byte Community ASN?

I am BGP peering with a Juniper OS router. When starting the connection, my system advertises 4-byte ASN capability, which is accepted by the Juniper router: Jul 28 00:33:00.664202 BGP RECV 4 Byte ...
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1answer
103 views

Max AS path to accept from peer?

I heard that once AS receives a BGP update that is longer than 50, it will be dropped. Is this true or just happens with some ISPs specifying that policy? I cannot find any evidence or official ...
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1answer
70 views

ISP lab GNS3 - BGP route exchange

I'm trying to develop an understanding of the WAN/ISPs. Eventually I'll build up to MPLS, but for now I'm trying to lab up a notional, basic ISP: R1, R2, and R4 are PE routers. They've successfully ...
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1answer
66 views

Thousands of open BGP ports at some organisations - Is there a reason for this?

I hope this is the right place to ask this, but I've been browsing Shodan in the hope of gaining some insight as to how many services my organisation has that are externally accessible so I can work ...
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2answers
84 views

BGP source base routing question

This question is little convoluted to explain but i will try my best, I have following scenario. I have one ISP and i am getting 2x40G drops which you can see in diagram Link-A and Link-B (Both ...
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1answer
93 views

How to announce network to specific neighbor peer in BGP

I have following scenario where i already have 10G (A - BLUE Link) connectivity from ISP on SW1 and SW2 for redendency and i have configured eBGP and iBGP, Everything is good at this point, Now my ...
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1answer
130 views

AWS direct connect BGP issue

This is out current setup and everything working great!!! here, now i want backup link for AWS so i have request for one more secondary link and terminated on Cisco ASA on Port-channel1.8 interface. ...
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1answer
42 views

Why Connected Routes are not shown as RIB failure in BGP Table?

I know that “RIB failure” in a “show ip bgp” output indicates that a route offered to the RIB by BGP has not been accepted. But why then the connected Routes that are being advertised by the BGP ...
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1answer
46 views

Redundant internet connection with multiple lte modems

Hy i wan't to build a Redundant Internet Gateway to use multiple usb LTE Modems with diffrent SIM Cards. The goal of this is to install it on a Boat in a medium sized lake. The boat route is along the ...
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1answer
27 views

Edit BGP on IOS XE3

i need to edit my BGP Running , and add more Neighbor but when try this FiberISP-Cisco(config)#router bgp 203725 BGP is already running; AS is 203735 FiberISP-Cisco(config)# how to edit and add ...
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1answer
55 views

Why does source RTBH need uRPF

I'm trying to understand why source-address RTBH needs to be coupled with configuring uRPF on the edge ports. I've read RFC5635 and other vendor papers on this topics but I can't figure out the ...
2
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1answer
35 views

Traffic Destined to X Should Bypass a Certain AS Y

Let's say you do not want the traffic destined to your /8 prefix to traverse AS Y. How would you modify your BGP configuration to do that? Thank you for your time
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1answer
52 views

In what conditions an AS is triggered to broadcast BGP withdrawal message?

I'm not very familiar with the mechanism of withdrawing BGP announcements so welcome any comment. Assuming AS1 broadcasted to AS2 an AS path to its prefix and AS2 forwarded that announcement to the ...
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1answer
86 views

Question about BGP peering with your ISP

In you case you want to get rid of the static default route and you want to peer with your single ISP, do you need to announce any routes for your side ? I have the below config, is it enough for ...
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1answer
60 views

What is the preferred way to prevent a particular subnet from being sent to one ASN

I have the following network. I want to prevent Subnet 2, S2, from being routed outbound of ISPA (preferring ISPC is also acceptable). None of my ISPs use BGP communities. Given that this is a live ...
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3answers
71 views

Can SDN controllers inject or delete routes in a router?

I have seen that some SDN controllers implement a BGP plugin in their architecture (for instance, Opendaylight). But, since controllers do not sent or route packets, I wonder how and if they can ...
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1answer
64 views

Router BGP Next Hop

Why is the first Route preferred? IS there a logical reason?
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2answers
74 views

Hot Potato, algorithm of selecting route in router

I want to understand a "hot potato" principle. Given a router with 5 interfaces. The first interface gets a packet and has to decide to which interface this packet should be forwarded. I think the ...
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2answers
86 views

How does a route-map applied as outbound on a neighbor sees the redistributed ospf routes into bgp? Local or external?

Here's my scenario: Redistribute ospf routes into bgp Create a route-map that matches on route-type=local and modifies the nexthop (to 4.4.4.4 for example) Assign this route-map as outbound routemap (...
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1answer
43 views

range of AS numbers which are given out by RIRs

I need to have a range of AS numbers which are allocated by RIRs/NIRs. I guess it is every number from 0 to 2^32 except those below: 0 - reserved ASN 23456 - ...
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1answer
91 views

BGP route dampening

Does BGP dampening need to be configured on both ends of neighbor ships? Will it work if I only enable it on my end and not on the ISP end?
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2answers
65 views

VLans on small sites with no core switch

I have several small sites that are part of an MPLS network. Most of the sites have Cisco 1921 routers that are handing out DHCP for about 6 machines. Looking to add VOIP at these sites and thought ...
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2answers
85 views

can we do bgp route in cisco 2821 router?

I have a cisco2821 router and it has connected to one Internet service provider. Now i need to buy another one router so that i can have another Internet provider which can help me when one primary ...
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1answer
47 views

One AS, Multiple Site with different physical location and ISP, different prefix

I am looking to implement few servers at different location with own ASN having prefix of PI resources of /22 going to divide into 2 x /23. I am unaware of what challenges I can face. As the 2 sites ...
2
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1answer
123 views

BGP with OSPF configuration question

ISP - Sending default route to sw1/2 via eBGP sw1 - config router ospf 100 network 0.0.0.0 255.255.255.255 area 0 default-information originate always ! router bgp 100 bgp log-neighbor-...
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1answer
53 views

Regarding Infrastructure and Hardware

I am completely new to network engineering. So, I need some help to understand the things. I want to colocate my server with the datacenter with my own IP and ASN, do I have to have a router or a ...
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1answer
60 views

Routing the same prefix to different destinations on the same router

I have a Cisco Nexus 7000 and have configured static routes to reach my internal networks on the Nexus 7000. During a DDOS attack, the Nexus 7000 receives a more specific route via IBGP to re-route ...
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2answers
1k views

Difference between default route, partial and full routing table for a BGP session

What is the difference between default route, partial and full routing table for a BGP session? Does it affect the routes bird (or another BGP client connected to the session) sees?
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1answer
79 views

Regarding as-path-access-list

On the given router, my objective is to configure as-path-access-list so it doesn’t accept any prefixes originated by AS 1. Below are the command outputs: Coarse#sho ip bgp BGP table version is 7, ...
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1answer
34 views

Redistribution VLSM networks to BGP neighbour with summarized 24 bit mask network

I received public BGP AS with network with 24 bit mask. Is it possible, to advertise on BGP router VLSM networks summarized to 24-bit mask (not for class membership)? Example: I receive 112.112.112....
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2answers
257 views

Learned eBGP routes are advertised to iBGP neighbors but can't ping the loopback who's IP is configrued

I have a setup in my GNS3 where I am trying to understand some basic iBGP and eBGP concepts. Please refer to the diagram (I only took a screenshot of the part which is really required). I have ...
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1answer
182 views

Struggling inbound and outbound traffic engineering to/from iBGP peers at different POPs

We are a managed service provider running a small sized network in a single datacentre in Sydney. We've recently deployed a new POP inter-state in Melbourne (both are on the east coast of Australia), ...
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2answers
51 views

BGP update source basics

I have the following test lab: The configuration of 'King' is: King#sho ip int bri Interface IP-Address OK? Method Status Protocol FastEthernet0/0 192....
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4answers
1k views

Using IP subnet at multiple datacenters

We control IPv4 and IPv6 subnets. Now we'd like to use a part of a /24 IPv4 subnet at one datacenter and another part at another datacenter. I know that announcing the subnet on the internet at ...
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2answers
86 views

BGP: Route congestion

Using a BGP Multihoming design, is it possible redirect or modify any metric to determinate destination? Example: I detected that the most of users are having problem to access a webserver: high ...
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0answers
235 views

Internal BGP routing issue BIRD

I am trying to setup BGP using BIRD and to announce routes learned from eBGP to router 2 through Router1. The routes show up in the routing table of Router2, however I cannot ping any of them.. (From ...
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2answers
31 views

BGP - reaching routers from my Autonomous System through another AS

Assuming a link between routers in my AS fails and now I have two groups of routers not connected with each other. Each group is connected to a different AS through one of the routers. Will BGP find a ...
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1answer
178 views

Communication between BGP and OSPF routers

I will start with a scenario. Please excuse me if its a low-level question. Lets say there are 2 AS, AS 100 and AS 200. *In AS 100 there are 3 routers R1,R2 and R3 running OSPF and RB1 and RB2 running ...
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1answer
184 views

PC cannot ping each other when using BGP

I am confused about why PC-A cannot ping PC-B. When pinging PC-B from PC-A, it is always time out, according to tracert, the packet stops at R3 g0/1. But I think according to the route table, PC-A ...
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1answer
60 views

show IP BGP summary size in bytes per column

Given the image below: It says that it only has 1 peer and it is using 4568 bytes of memory. Does anybody knows how? how many bytes are each column on the table? As far as I know neighbor is 4 bytes,...
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2answers
55 views

Is s-bgp deployed and used?

Is s-bgp actually deployed/present on routers, or is it just an accademic protocol? Where is bgp security moving to (if it is moving in any particular way)?
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2answers
633 views

Why is ospf to bgp redistribution and simultaneous bgp to ospf redistribution dangerous?

I am referring to this question, where OP apparently fixed his issue by redistributing ospf in bgp and vice-versa on the same router. The user Sebastian warns that this is a dangerous practice. We ...
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1answer
77 views

Cisco BGP Prefix Lists

One of the benefits to Cisco's prefix lists is less CPU consumption over standard ACL`s. However I'm unable to find any further details. So my questions is - why are prefix lists more efficient in ...
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2answers
240 views

BGP Inbound Route Filtering

I would like know if it's possible to block access to a particular site eg: facebook.com, using BGP prefix filtering. For example, can I apply a filter to prefixes received from my ISP that drops ...
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1answer
275 views

Juniper SRX BGP based ECMP not working as expected

Overview I am trying to setup BGP based ECMP to two end servers that sit on separate subnets/VLANs and advertise out the same IP address to a SRX firewall. The end nodes are linux boxes running BIRD ...
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2answers
64 views

How does a ping to a public IP work in my same AS?

I am an ISP, I have a BGP session established with a larger provider. The question is, when from my network I ping a public IP, also inside my AS, Does the ping go to my provider and then come back, ...
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0answers
172 views

iBGP test setup with FRR/Quagga/Cumulus: got routing loop

I'm new to BGP and have set up a test environment with four virtual routers using Cumulus VX. swp1+---------+swp2 +----| leaf 1 |----+ / +---------+ \ / ...