BGP (Border Gateway Protocol ) supports authentication using the md5 (message digest 5) algorithm. For authentication to be successful md5 authentication should be configured on both sides. When authentication is enabled when any TCP segment belonging to BGP exchanged between peers is accepted only if the authentication is successful. router bgp 100 no synchronization bgp [...]
You can configure data and voice vlan on the same port. You can’t configure the two access vlans on single port. When you configure the data & voice vlan on single port in that scenario. From the switch port first cable goes to voip phone. VOIP phone has two port one for the input and [...]
OSPF routers on multiaccess segments sync their databases with their Designated Router (DR) or a Backup Designated Router (BDR) only. The OSPF status between two routers transitions to Full only if at least one of them is a DR or a BDR. The state remains Two-way between a pair of routers if both routers are drothers.
Usually passive interface command is used in routing protocols to accept information from neighbors but prevent it from sending information to neighbors But in case of EIGRP (Enhanced Interior Gateway Routing Protocol) it is exactly opposite.EIGRP discovers neighbours using the hello packets,before accepting routes and installing them in the routing table. Hello messages are usually [...]
If there are multiple EIGRP and OSPF neighborship flap over the GRE tunnel what could be the problem and how would solve it?
If in the logging you are getting the error message %TUN-5-RECURDOWN: Tunnel0 temporarily disabled due to recursive routing It means that GRE Router tunnel has found a recursive routing problem. The symptoms of this issue include the continous flapping of tunnel interface as well as EIGRP,OSPF & BGP neighbours when neighbours are over the GRE. [...]
-If there is a data center outage or power outage, both vPC peers consisting of Nexus 7000 Switches are down. Sometimes, only one of the peers can be restored. Since the other Nexus 7000 is still down, vPC peer-link as well as vPC peer-keepalive link are also down. In this scenario, vPC will not come [...]
If Border Gateway Protocol (BGP) is not propagating any internal BGP (iBGP) learned routes to another iBGP peer because it requires a full iBGP mesh within the Autonomous System (AS). To overcome this issue you can configure BGP router as a route reflector By configuring a BGP router to be a route reflector, a full [...]
How to configure ACLs that permit only established connections and deny all traffic sourced from the external network
Adding the established keyword at the end of access-list indicates that packets belong to an existing connection if the Transmission Control Protocol (TCP) datagram has the Acknowledgment (ACK) or Reset (RST) bit set. access-list 110 permit tcp any any established When you add this make sure you enable DNS otherwise the url will not able [...]
In order to prevent Enhanced Interior Gateway Routing Protocol (EIGRP) updates from overwhelming the interface, Cisco IOS provides controls how much bandwidth it can consume on the physical interface. By default, EIGRP limits itself to using no more than 50 percent of the interface bandwidth. Although, this is not very significance on high speeds like [...]
If BGP is used in multihoming scenario then primary link gets fail, after how long traffic will be shifted to secondary link?
By default, fast external failover is enabled for eBGP neighbor. So when the egress interface fails, it immediately bring down the BGP session and next best path will be selected. if you have it disabled, it will rely on the BGP holdtimer.
In the multihomed environment load balancing is not an option because BGP select only one best path to destination when the BGP routes are learned from different AS’s.To achieve this we need to setup a better metric for the routers in the range 0.0.0.0 to 184.108.40.206 that are learned from ISP A and better metric [...]
There are three types of BGP Routing tables: a) Adj-RIB-in b) Adj-RIB-out c) Loc-RIB Adj-RIB-in stores the unprocessed information received from its peers. Here the best path selection occurs as per BGP attributes and after conformation path is entered into the local bgp table i.e Loc-RIB. From the local RIB table it conform the next-hop [...]
EIGRP can utilize 5 separate metrics to determine the best route to a destination: Bandwidth (K1) Load (K2 Delay of the Line (K3 Reliability (K4) MTU (K5) By default, only Bandwidth and Delay of the Line are used
Conditions to form EIGRP neighbors -It must receive HELLO PACKET from neighbor router -EIGRP AS number should be same -Must have identical K-values or Metric -Adjacencies will not form unless the primary IP addresses on connecting interfaces are on the same subnet.
SoO for BGP is “linked” to CE-neighbor. So, when a prefix needs to be advertised to a CE neighbor, we check the SoO of the prefix with the SoO of the BGP neighbor. For anything else, it is linked to interface. The configuration can be done in four ways –“route-map in” on CE BGP neighbor [...]
EIGRP uses AS (Autonomous system) number ranging from 1-65535 to identify collection of routers that share same information. EIGRP have less convergent time and is more efficient EIGRP supports both auto and manual route summarization Supports multiple routed protocols like IP ,IPX and apple talks EIGRP converges rapidly in the event of link failure EIGRP [...]
Below are the basic BGP timers Keepalive timer- 60 seconds Hold-down timer-3xkeepalive or 180seconds Advertisement interval- 30 seconds for eBGP peers and 0 seconds for iBGP peers Scan timer-60 seconds Did i miss anything please let me know through Setting->Feedback option
In the BGP the current versions i.e BGP-4 version supports CIDR
Private VLAN is a layer 2 network structure which an extension of the common VLAN technology. Within a Private VLAN domain there are three very different port designations exist. Each port designation has its own unique set of rules, which regulate a connected endpoint’s ability to communicate with other endpoints connected to ports within the [...]
5 networks route update RIP receives at once.
To set up the SUP engine redundancy one must have the same version of iOS. Once Sup engine redundancy is configured one switch will act as Active Sup and the other will act as standby sup engine Cisco6500(config)# redundancy Cisco6500(config-red)#keepalive-enable Cisco6500(config-red)#mode sso Cisco6500(config-red)#main-cpu Cisco6500(config-red-main-cpu)#auto-sync running-config SSO (Stateful Switch over) mode means it will sync the [...]
TCP is a connection-oriented protocol both ends of a connection keep strict track of all data transmitted, so that any lost or jumbled segments can be retransmitted or reordered as necessary to maintain reliable transport. To compensate for limited buffer space (where received data is temporarily stored until the appropriate application can process it), TCP [...]
There are two access-lists are allowed per interface. One in Inbound direction and other in the Outbound direction.
Cisco router generates a source quench only if it doesn’t have the buffer space needed to queue the packet. If the router can not queue the routed packet onto the output interface’s queue, it generates a source quench and registers an output drop against the output interface. If the router is not congested then it [...]
PAgP Port Aggregation Protocol (PAgP) is a Cisco proprietary protocol used for automated logical aggregation of Ethernet switch ports. PAgP has two modes Auto this mode sets the interface to respond to PAgP negotiation packets, but the interface will start negotiations on its own. Desirable this mode sets the interface to actively attempt to negotiate [...]
HSRP * Cisco proprietary * 1 Active & 1 standby router & 1 or more listening routers * use virtual ip address as gateway * hello 3 sec & holddown timer 10 sec * we can enable preempt manually (standby 1 preempt) 6) multicast at:220.127.116.11 (ver1), multicast at:18.104.22.168 (ver2). Both versions use udp port 1985 [...]
n7010# show incompatibility-all system bootflash:n7000-s1-dk22.214.171.124.bin ‘show incompatibility system’ shows configuration incompatibilities between the running system image and an another system image prior to downgrading/upgrading the Cisco NX-OS software.
In a 48 port switch if there are 5 vlans. There will be how many collision domains & broadcast domains
There will be 48 collision domains because every port on switch is collision domain. There will be 5 Broadcast domain as each vlans is broadcast domains.
When enabled globally, BPDU guard has these attributes: *If a BPDU is recieved by the port it will fall-back to normal STP operation (instead of Portfast) and go through the normal STP states When enabled on interface, BPDU guard has these attributes: *It will err-disable the port Exclusive promotion for our users checkout the 70% [...]
When enabled globally, BPDU filtering has these attributes: *It affects all operational PortFast ports on switches that do not have BPDU filtering configured on the individual ports. *If BPDUs are seen, the port loses its PortFast status, BPDU filtering is disabled, and the STP sends & receives BPDUs on the port as it would with [...]
BPDU’s are the messages exchanged between switches to calculate the spanning tree topology.Bridge Protocol Data Units (BPDU’s) frames contain information regarding the Switch ID, originating switch port, MAC address, switch port priority, switch port cost etc. Bridge Protocol Data Units (BPDU’s) frames are sent out as multicast messages regularly at multicast destination MAC address 01:80:c2:00:00:00. [...]
* Etherchannel * Stackwise * VSS (Virtual Switching System) * HSRP (Hot Standby Routing Protocol) If you want to add more in this answer you can send your feedback to us from Settings->Feedback CCNA Routing & Switching by Wendell Odom is perfect way to prepare for CCNA. Checkout the book on Amazon.in Amazon.com
In Cisco 6500 you can check the backplane utilisation using the command ‘show catalyst6000 traffic-meter’ ______________snip_______ sh catalyst6000 traffic-meter traffic meter = 10% peak = 25% at 01:23:17 CST Fri Sep 4 2014 ___________snip_________
The main difference is -6500-E chassis offers enhancements to support the 67XX and the 68XX series linecards. -6500-E chassis offer enhancements which increase the overall system power capacity for Power over Ethernet (PoE) port density scalability.
RSTP(Rapid Spanning Tree Protocol-802.1w Standard): it is the enhanced protocol of STP, the main caracteristic of this one is Faster than STP (it converge in less than 6 seconds). PVST+ (Per Vlan Spanning Tree Plus) : This feature is used to create an instace of STP for each VLAN. e.g. If you have a switch [...]
In basic HSRP configuration one active router does all the forwarding for all its hosts, and the standby router is simply used only if the active router fails. Load balancing with HSRP requires the creation of two HSRP groups. GLBP has the redundant gateways which share multiple virtual MAC addresses. Both routers are considered active [...]
FWM means Forwarding Manager. It is a mechanism to count the number of MAC-move-backs and weigh them based on the number of times the MAC address moves.It determines the total MAC-move-backs count (switch-wide across all VLANs, MACs, and interfaces), declares the message in the log %FWM-2-STM_LOOP_DETECT, and disables learning to protect FWM in loopy conditions. [...]
We have one router,we are using two routing protocol eigrp 90 net 10.10.10.0/16, ospf 110 net 10.10.10.0/24 on same router, Is it possible?
Yes this is possible, it works according to Ad value.If eigrp & ospf are on the same routers then it will take automatically eigrp route according to AD value.
The DR/BDR elections are not pre-emptive.So first thing that happens is a router will listen to the hello’s and see who else is out there. If nobody there, then it asserts itself in position. If there someone else at the same time, then they’ll either challenge (better info) or acquiesce. Even if the one who [...]
What will happen if two switch are connected to each other by two cables and spanning tree is disabled?
When a redundant connection is made, we will start receiving MAC address flapping notifications such as %SW_MATM-4-MACFLAP_NOTIF: Host 003b.20c2.0264 in vlan 1 is flapping between port Fa0/4 and port Fa0/5 These are triggered by the never-ending broadcast storm initiated by every layer two broadcast (such as an ARP request) from any host on the VLAN. [...]