Questions tagged [bgp]

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

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17 views

Problem with bgp aggregate-address behavior in iOS when a large number of OSPF routes update all at once

We have a direct connect setup to AWS using BGP. We are running a ISR4451 with IOS XE 16.03.06. I have a strange situation where the AWS BGP neighbor drops our connection with the notification: ...
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Why do eBGP neighbors need to be physically connected to each other

In Halabi - Chapter 6 it states that, "External BGP neighbors have a restriction in that they must be physically connected, adjacent to one another." There are tuning knobs that lets us override this ...
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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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1answer
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Summarization on received Routes - BGP

We need to do Summarization on received Routes (as we are receiving 20K+ routes )to reduce load, saving memory, bandwidth, and CPU Cycle. Please suggest some quick and accurate methods to do. I m ...
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IGP between 2 routers with an uncooperative router in the middle

I've got two routers, A and B. A gets some routes over BGP over a VPN connection, and has a leg on 10.0.0.0/24. It also can access the whole 10.0.0.0/16 via its default gateway. B is on 192.168.0.0/...
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How to C3850 activate license to ipservices

We have Cisco C3850 running ipbase license recently we decided to run BGP protocol for that we need ipservices license. Question: Do i need to buy new license or i have already that i just need to ...
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Why use iBGP inside an Autonomous System, if IGP protocols fulfill the need for internal communication

Can anyone explain why we need iBGP for the routes when we have the IGP protocols (OSPF, RIP) for internal communication within the AS? I have read a lot of articles and books, but I could not find ...
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1answer
258 views

In practice, how are BGP Advertisement destinations determined and configured?

Say there is ISP-Alice (ISP-A) and ISP-Bob (ISP-B). They both serve neighboring areas, but they currently only peer with ISP-Charlie. They want to change that and peer directly with each other to ...
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How much RAM you actually need to keep whole global BGP routing table?

It seems that different sources claim very different RAM consumption for having whole BGP routing table information in RAM and having the router to correctly route the traffic. According to ...
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How do two clients of a route reflector learn about each other when no IGP/static-route is used?

I recently learnt that Route reflectors are an efficient alternative to full mesh IBGP peering in a large AS. Imagine a network like: D1 - AS1 <e> R_P <i> RR <i> R_Q <e> AS3 - ...
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Local pref VS prepend AS-path for two eBGP router

I have two routers, AS50 and AS100, both are under my control. Since they are using different ASN, they should be eBGP routers. These two routers are connected by internet VPN and lease line, which ...
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How a single BGP-process establishes sessions with neighbours in different VRFs?

In VRF-lite solution scenario, when BGP session is established between CE connected to a VRF in PE. The BGP process or in other words TCP server, is listening on port 179(default) for incoming BGP ...
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Cisco N9K - Down an interface in response to another interface going down?

I currently have my transit providers plugged directly into my router. I really like this arrangement because when the ISP goes down this typically downs the interfaces which results in BGP peering ...
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2answers
490 views

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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1answer
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Understanding the BGP Peer point, BGP Peer and BGP peering session

In my test case, there have 3 ASs. the connections is below: I want to use this case to understand the BGP peer , BGP peering point and BGP peering session. in my understanding: BGP peer means the ...
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Can I assign one of my publicly available IP address to my AWS instance?

I would like to be able to use one of my publicly accessible ip addresses directly with my aws cloud instance. Is there a way I can assign or transfer one of my ip address to aws? My ARIN registry ...
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314 views

BGP <-> OSPF Route Redistribution Loops

In the following topology I have a multi-point redistribution from BGP <-> OSPF and I have recently encountered a routing loop. After further reading I have understood the problematic routers ...
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What are the benefits of using MP-BGP multicast address family, under the context of inter PIM domains multicasting?

Under the context of inter PIM domains multicasting, 1 RP on each PIM domain (2 domains), attached with eBGP, with MSDP peering to exchange the actives sources, what are the benefits of using the MB-...
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What is the minimum number of IP addresses an autonomous system can have?

Is it possible to have an autonomous system with just one IP address?
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BMP Server on Cisco [closed]

I'm using router Cisco 2900 series with Cisco IOS 15.4(3) M3, and there is no BMP (BGP Monitoring Protocol) configuration. What should I do? What Cisco IOS version that provide BMP?
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1answer
548 views

Juniper "show route receive-protocol bgp" output meaning

When you show the received route from a specific neighbor in BGP with a Juniper, the output is the following : show route receive-protocol bgp X.X.X.X inet.0: V destinations, W routes (X active,...
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35 views

public ip over private lease line

I have a private cross-connection with a service provider This private connection is connected from my firewall to their router and the L3 IP range /30 for this segment is private However, i just ...
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BGP default behavior for tie breaker [duplicate]

If routes having same AS path to reach the destination, how the BGP will tie break without using any BGP attribute filter? Bandwidth also same on both sides. How its choose the best path. Please ...
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BGP Cisco best practices to filter client asn and prefixes

I have two bgp routers. OSPF as IGP and on Loopback's iBGP. Both routers have different peers, but both receive full routing table. I have to connect client through BGP and give him full table. Client ...
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Valid routes iBGP advertisements

Routers announce to their iBGP peers, the Best routes for each networks it has in its database Is it possible, to announce additionally to the Best route, also all the Valid routes to the iBGP peers ?
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iBGP Question reagrding Distribute - List from EIGRP

So, I have the following topology. A-B | | C-D A-B-C-D are Routers. It doesn't matter what are the IP's of the interfaces. What matters is that I have 2 loopbacks for each router. 1.1.1.1 and 11.11....
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BGP Traffic Engineering - Active\Passive

At my organization we historically would get T1 ISPs at our POPs and take full table + default. BGP would simply "do it's thing" and for the most part everything worked out. There are ...
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1answer
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Understanding BGP communities

Lets take this basic topology: RTR A ---- RTR B Routers A and B have an eBGP connection. At router B we can have a route map saying: match: community-list xyz action: permit/deny etc Questions: How ...
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1answer
92 views

How to configure loopback for switch management

We have Cisco Switches (Nexus 93). My PC is on vxlan, in vrf "test" with default gateway 60.254. We want to use loopback 99 for managent for switches. We have created a loopback 99 with an ...
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222 views

How to redistribute BGP routes learned from AWS in one VR into another BGP running in another VR in Palo Alto firewall?

I have about 1000+ prefixes I am learning from AWS on Palo Alto through a BGP. This is on the secondary VR. Main VR is where my core routing is situated along with another BGP instance pointing to ...
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1answer
965 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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2answers
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How to isolate in VRF clients with public IPs in MPLS ISP network

I have OSPF and MPLS enabled in network and run xconnects to transmit L2 traffic. But also have just Internet clients that want public IP addresses. So I configure public IP on interface towards ...
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What determines if a Juniper router is a route reflector client?

When I read bgp router reflector document: You see the topology is this: You see the Router A B C are in one cluster, D E are not clients of it. but how to configure to become this? I compared with ...
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1answer
170 views

Cisco IOS XR not sending multiple copies of a prefix despite that the additional-path feature is enabled

I have an iBGP session between a Juniper router and a Cisco IOS XR router with add-path/additional-path both in send and receive direction enabled. According to show bgp neighbor, the feature is ...
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1answer
108 views

BGP route advertised but cannot Ping

I have this rather basic setup with 3 routers running BGP, each has Loopback int configured. Is there an extra step required for R2 to ping R4 Loopback interface despite it's being advertised? R2#sh ...
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63 views

BGP-OSPF route injection doesn't work

Background: BGP is fully functional and works as expected so nothing need to worry about, the problem is the route injection between HK_Office <> HK2 and LON1 <> LON_Office, as you could ...
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2answers
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Why the iBGP's loopback network is not valid in AS?

This is my test topology: this is my Routers' detail configuration: <R1>display current-configuration # sysname R1 # router id 1.1.1.1 # aaa authentication-scheme default authorization-...
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1answer
43 views

Why the iBGP received network is not valid?

I test the BGP in my PC, this below is the topology: R1--(eBGP)--R2--(iBGP)--R3. and R2-R3-R4 are in OSPF(omit details). this is my detail configuration of BGP: [R1-bgp]dis this # bgp 100 peer 10.1....
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1answer
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Change BGP Dampening parameters for a specific neighbor

When you configure the BGP Dampening, the configuration is set for all eBGP neighbor in a Cisco router. There is a way to customize the parameters for a specific neighbor ?
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Peering of ISPs

How does having multiple peers affect an ISPs performance? If I have 2 option of ISPs to select from, where ISP1 has only 2 peers and ISP2 has 10 peers, which one should I select? Or does number of ...
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1answer
44 views

Why the route comes from different AS?

Before, I know the AS path of BGP properties, such as the 200 100i means the route originate from AS100, use network import the route and through AS200, however in my case: admin@MX480> show route ...
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Redirect Junos IP public -> IP private

we have an MX204 here that works as our BGP, border router and it is gateway of a service that has private IP, I need to access this service with private IP outside our network, you can tell me if I ...
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1answer
41 views

What's the BGP route `active received accepted damped` status meaning?

when I use show bgp summary command in Juniper router: admin@LA-MX-RE0> show bgp summary Groups: 20 Peers: 20 Down peers: 3 Table Tot Paths Act Paths Suppressed History Damp State ...
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3answers
488 views

Multihoming with two 'good' providers - load sharing strategy?

We get two 100G links, one from each provider and our aggregate traffic is sub 100G. The rationale is one provider can fail and the other will pick up the slack with zero degradation. Our traffic ...
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321 views

VXLAN working over IGP, but no NVE peers or EVPN routes in BGP

I'm an absolute beginner with NX-OS and VXLAN. I'm trying to set up a very simple configuration for VXLAN/EVPN/BGP. I have one NX-OSv spine and two leaf switches. No VPC, no anycast SVI. The ...
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1answer
35 views

BGP Cisco internal and external distance

I have two bgp routers. OSPF as IGP and on Loopback's iBGP. Both routers have different peers, but both receive full routing table. In google I found on many presantations "bgp best practisec&...
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5answers
5k views

How to view BGP community attached to prefix in Cisco ASR routers?

Cisco ASR routers use IOS XE software. One can see the received IPv4 unicast prefixes from BGP neighbor before any inbound policies with sh bgp ipv4 unic neigh <neighbor-address> received routes ...
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3answers
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Why are iBGP routes not propagated to other iBGP neighbors?

I have been searching this on the web. It is generally expressed as by default, iBGP does not propagate routes learned via other iBGP neighbors. I am trying to understand the underlying reason. The ...
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3answers
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How do Metropolitan Area Networks (MAN) interconnect?

If an organization in a city (perhaps New York) has multiple offices within that city, how would they interconnect their LANs? I already understand that they will connect to an ISP, but my question is:...
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1answer
66 views

Can't send message from RIP to static through BGP

Before deep into the question, please see this topology and the results of sending messages from one router to the other router: I have succeeded in sending a message from R0 to R2 (or vice versa), ...

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