• Tag : routing


BGP Routing Issue

I have constructed a Lab with a Single Spine and 2 Leafs which are interconnected over MLAG link. Initially everything is perfect. Before i start with the problem  statement – this should be known   Loopback 0 on the Spine is , Loopback 0 on Leaf1 is and Loopback 0 on the Leaf2 is   On the Spine : when i do show ip bgp and show ip bgp following is the results   SPINE#show ip bgp BGP routing table information for VRF default Router identifier, local AS number 65001 BGP routing table...
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Multicast tree control in multi-tiered fabrics

Description Multipath color is a new multicast multipath mode for controlling PIM RPF selection. In the default multipath deterministic mode, multiple PIM routers with the same set of ECMPs to the source may make a different RPF selection decision. This may result in wasted bandwidth consumption since traffic may be unnecessarily duplicated. In multipath color mode, all PIM routers with the same set of ECMPs to the source make the same RPF selection decision (per source-group). Traffic is load balanced across ECMPs by source-group. Upstream PIM routers advertise a multipath color value in the PIM Hello message that downstream PIM...
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EOS support for class E addressing ( 240/4 )

Description The feature allows assigning of class E addresses to interfaces by default with no option to turn that off and routing of E class addresses remains disabled by default. The feature provides a cli command that enables E class addresses to be routed through BGP, OSPF, ISIS, RIP, static routes and programmed to the FIB and kernel. Class E reserved addresses are 1/16 of the total address space so the option to use them extends potential deployment scale. Platform compatibility This feature is platform independent. Configuration This feature is configured under router general config. Command: [ no | default...
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MAC Address Configurability on Routed Interfaces

Description For various peering applications, there is a need to support the assignment of a MAC address on routed interfaces. This feature adds the support for MAC address configurability on the following types of routed interfaces: Ethernet interfaces  Sub-interfaces on ethernet interfaces Port-channel interfaces Subinterfaces on port-channels VLAN interfaces This feature enables the following capabilities: A fully specified unicast MAC address can be configured, i.e., the new MAC address may not be from Arista’s allocated OUI space or derivative from the device’s base or system MAC address. A single MAC address can be assigned to multiple interfaces on a device....
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Routing Control Functions

Description Routing control functions (RCF) is a new language that can be used to express BGP route filtering and attribute modification logic in a powerful and programmatic fashion. It supports a new set of workflows to define and apply these functions in EOS. The broader feature set includes: The base RCF language framework; Support for RCF function application to BGP neighbors; Support for matching and modifying BGP protocol attributes; Workflows to define and apply routing control functions; CLI commands to provide visibility into operational status. The following points of application are supported: Point of application Supported since Inbound BGP neighbor...
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CLI error for references to unconfigured policy constructs

Description This feature adds a configuration option which provides a CLI error if a reference is made to an unconfigured policy construct in a route map sequence. It will also provide a CLI error if an attempt is made to delete the configuration for a policy construct which is referenced in an existing route map sequence. The error only takes effect during interactive CLI sessions – i.e. when interacting directly with the CLI, or using a configuration session, or using eAPI configuration. The error does not take effect when loading the configuration at switch startup, or during configuration loading replace....
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Configurations and Optimizations for Internet Edge Routing

Introduction For many years, network deployments for enterprise Internet edge environments have consisted of dedicated routing platforms and a switching or aggregation layer to distribute this to various network zones.  With the advances in merchant silicon forwarding engines and the software expertise put into Arista’s Extensible Operating System (EOS), we can now fully replace this legacy architecture with a collapsed routing and switching layer using Arista R Series platforms.  Arista R Series platforms allow for holding a full copy of the Internet routing table for both IPv4 and IPv6 in hardware (the Forwarding Information Base, or FIB) with plenty of...
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Newbie question about default routes

Hello, A pair of Arista DCS-7020SR switches (running 4.23.0F) which will be used as L3 routers. All routing interfaces are in port-channels with VRRP configured. My question is: how do I specify different default routes for management and data traffic? Would the config below work? Many thanks. ! vlan 20 name EXTERNAL- ! vlan 30 name INTERNAL- ! interface Port-Channel20 switchport trunk allowed vlan 20 switchport mode trunk ! interface Port-Channel20.20 encapsulation dot1q vlan 20 ip address vrrp 20 priority-level 200 vrrp 20 peer authentication ietf-md5 key-string 7 XXX vrrp 20 ipv4 ! interface Port-Channel30 switchport trunk allowed...
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A Simple OSPF Configuration

At this point in your networking career you’ve mastered the L2 domain. I can recall several years ago when I was an embedded software engineer (programming NPUs – Network Processing Units for a networking startup) meeting a colleague that was a master of the L2 domain. This individual knew everything you wanted to know about L2, including non-Ethernet protocols. Then came the day when I was drawing a network diagram with L3 interfaces and diagramming the packet formats at the points of ingress and egress through each L3 hop. My L2 Grandmaster looked at me with a blank stare. I...
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RIB route control: next hop resolution policy

Description RIB Route Control is a collection of mechanisms for controlling how IP routing table entries get used. Next hop resolution policy adds support for preventing recursive resolution of next hops based on route map evaluation of resolving routes. Platform compatibility Next hop resolution policy is a platform independent feature. Configuration Next hop resolution policy is configured for a particular VRF with the rib ipv4|6 resolution policy command under router general. Arista(config)#router general Arista(config-router-general)#vrf default Arista(config-router-general-vrf-default)#rib ipv4 resolution policy MAP1 Dependant routes whose resolving route is permitted by the route map will be recursively resolved, and dependant routes whose resolving route is denied...
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ribd vs multi-agent (ArBGP)

My organization is developing lab scenarios to move our network towards implementing EVPN. Part of that process is to add the: service routing protocols model multi-agent command. We have found a few unique situations where the default behavior of routing (outside of BGP) has changed. For example: OSPF summary routes not working Static routes to unreachable next hops (while the interface is up) are not placed in the RIB. I have been unable to find any documentation outside about what actually changes when implementing that command. Is there a white paper about it, or a list of default behaviors that...
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1 or many vlan interface

Hi – new to Arista, first time setting them up. I’m using a 7020R effectively as an access layer device, 2x 10Gb in a port-channel to our core device. My question is related to static ipv4 routing on the 7020R. I have tried 2 approaches and they both seem to work with next to no testing. 1) Using a single vlan interface on the 7020R, assigning an ipv4 address, this creates a ‘Connected’ route then using static routes to point everything to the single vlan interface. Or… 2) Using a vlan interface per vlan, assigning each an ipv4 address and,...
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VXLAN Indirect Routing on 7280E, 7280R and 7500R series

In EOS-4.18.0F, VXLAN direct routing was introduced on the 7500R and 7280E/R series platforms. VXLAN routing provides the capability to route between VXLAN Layer 2 domains. In EOS-4.18.1, support for VXLAN Indirect Routing model is added to the 7500R and 7280E/R series platforms. In the Indirect routing model, the destination host is not directly attached to the VTEP(s) where the default gateway functionality is present. This model is called “indirect” because, in this model,  the packet possibly needs to go through multiple hops in the overlay to reach the final destination. It typically involves running routing protocols in the overlay...
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Overlay IPv6 routing over VXLAN

Overlay IPv6 routing over VXLAN Tunnel is simply routing IPv6 packets in and out of VXLAN Tunnels, similar to VXLAN overlay IPv4 routing. Underlay ( Outer IP Header ) in VXLAN still uses IPv4, and common for both overlay IPv4 and IPv6 . Hence VXLAN configuration remains exactly same for both IPv4 and IPv6 overlay routing support. This feature enables IPv6 networks/hosts get connected through VXLAN Tunnels. Following figure illustrates IPv6 routing followed by VXLAN encapsulation to reach a remote host across the VXLAN tunnel.   Following figure illustrates VXLAN decapsulation and routing of an IPv6 packet. Platform compatibility DCS-7050X DCS-7060X DCS7260X DCS-7050X2 DCS-7250X DCS-7304 / DCS-7308 /...
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Arista EOS – BGP Selective Route Download

Today, various content provided through the Internet continues to grow exponentially. Content Providers have spent significant CapEx dollars for their infrastructure typically peering with multiple providers to give their customers the best experience possible. This classically calls for BGP peering between these providers and leveraging one provider as a transit with a default route. Given the fact that many views of the global Internet routing table show approximately 580,000 IPv4 prefixes and 20,000 IPv6 prefixes (December 2015), large expensive routers are traditionally used in this capacity. This is because traditional deployments in the past took all the routes in the...
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VXLAN Routing with MLAG

Introduction This document describes the operation and configuration of  VXLAN routing on an Arista platform in conjunction with MLAG for redundancy. The configuration and guidance within the document unless specifically noted is based on the platforms and EOS releases noted in the table below. Arista’s Multi-Chassis LAG (MLAG) technology provides the ability to build a loop free active-active layer 2 topology. The technology operates by allowing two physical Arista switches to appear as a single logical switch (MLAG domain), third-party switches, servers or neighbouring Arista switches connect to the logical switch via a standard port-channel (static, passive or active) with...
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How to route to external subnets from VXLAN subnets and vice-versa

Hi,   I was able to setup Vxlan between Host1 and Host2 which are in Vlan 600 subnet Host1 and Host2 are able to reach each other via Vxlan. However, I want to know how do I setup the routing to external hosts outside the subnet? Below are the configs for both VTEPS. VTEP1 switch has a network that Host2 is trying to reach. Thank you VTEP1 (Switch1): spanning-tree mode mstp ! no aaa root ! vlan 492,600 ! interface Port-Channel2000 no switchport ip address ! interface Ethernet1 no switchport ip address ! interface Ethernet2 no switchport ip address...
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BGP METRIC attribute

Hi, I was trying to find out how do I configure Metric BGP attribute? I look all over the Arista commands and could not figure it out. Thank you   Victor

Programmatically update your routing table

Overview This article describes a script which is designed to allow the insertion/removal of a route in/from the routing table. If you want a way to remotely add/delete routes to/from your routing table, then this is the tool for you – using it will make insertion/removal of static routes as easy as running a script on any remote device that supports Python. How to get the code: Download the code Use your Github account and fork it (remember to contribute back) Installation The script (updateRoute) can be run/installed on any device that runs Python 2.7 or later. In order to run updateRoute, first...
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