EtherChannel allows you to aggregate several switch links into a single, fast, fault-tolerant, logical interface. 16 links can be defined for an EtherChannel, however, a maximum of 8 will be active at any one time. The other links are placed on standby.
While having multiple links between two switches can possibly create bridging loops, EtherChannel avoids this by bundling the links into a single logical interface. This logical interface can be configured as an access or trunk interface.
For ports to be members of the same EtherChannel, there are some restrictions. Ports must:
The full duplex maximum bandwidth for 8 links is as follows:
EtherChannel load balancing across the links can occur in a number Continue reading
The other day I was at work doing an interoperability test with Cisco and Brocade multilayer switches, and we ran into a strange issue that really highlighted my “tunnel view” to the Cisco world.
We were setting up basic OSPF stuff using md5 authentication and we couldn’t get the Cisco and Brocade to form an adjacency. A debug ip ospf adjacency command on the Cisco switch revealed that the Cisco was using “type 2” authentication, and the Brocade was using “type 0”.
Here’s a quick breakdown of the authentication types:
Type 0 | No authentication |
Type 1 | Clear text authentication |
Type 2 | md5 authentication |
I set up a SPAN on the Cisco switch and sure enough, we were getting the OSPF Hello packets from the Brocade with no authentication.
After some digging, it turns out the Brocade has an Auth-Change-Wait-Time command in interface configuration mode. This is set to 300 seconds (5 minutes) by default. While I don’t quite understand it, the description states it allows for graceful authentication implementation. So after you enable md5 on the interface, it waits 300 seconds before actually sending OSPF Hellos with authentication. We toyed around with it Continue reading
Vulnerability Details
OSPF LSA Manipulation Vulnerability in Multiple Cisco Products
· Summary
Multiple Cisco products are affected by a vulnerability involving the Open Shortest Path First (OSPF) Routing Protocol Link State Advertisement (LSA) database. This vulnerability could allow an unauthenticated attacker to take full control of the OSPF Autonomous System (AS) domain routing table, blackhole traffic, and intercept traffic.
The attacker could trigger this vulnerability by injecting crafted OSPF packets. Successful exploitation could cause flushing of the routing table on a targeted router, as well as propagation of the crafted OSPF LSA type 1 update throughout the OSPF AS domain.
To exploit this vulnerability, an attacker must accurately determine certain parameters within the LSA database on the target router. This vulnerability can only be triggered by sending crafted unicast or multicast LSA type 1 packets. No other LSA type packets can trigger this vulnerability.
OSPFv3 is not affected by this vulnerability. Fabric Shortest Path First (FSPF) protocol is not affected by this vulnerability.
· Affected Products
Cisco devices that are running Cisco IOS Software and configured for OSPF are vulnerable. Devices that do not have OSPF enabled are not affected by this vulnerability.
Cisco devices that are running Cisco IOS Continue reading
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Company ABC is in process of configuring BGP Confederations between its sites. During a small transition period, there will be no BGP between R3 and R2, but instead only static routing. Have a look at the quiz and try answering the question !
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The post The Importance of Effective Communication at Work appeared first on Packet Pushers Podcast and was written by Paul Stewart.