© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v3.05-1 Implementing High Availability in a Campus Environment Configuring Layer 3 Redundancy with. - презентация

1 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Implementing High Availability in a Campus Environment Configuring Layer 3 Redundancy with HSRP

2 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Routing Issues: Using Default Gateways

3 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Routing Issues: Using Proxy ARP

4 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Router Redundancy

5 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Router Redundancy (Cont.)

6 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v HSRP Standby group: The set of routers participating in HSRP that jointly emulate a virtual router

7 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v The active router responds to ARP requests with the MAC address of the virtual router. The Active Router

8 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v The Virtual Router MAC Address

9 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v The Standby Router The standby router listens for periodic hello messages on

10 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Active and Standby Router Interaction

11 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v HSRP States An HSRP router can be in one of six different states: Initial Learn Listen Speak Standby Active

12 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v HSRP State Transition Initial Listen ActiveSpeak StandbyListen Speak Standby Router A Priority 100 Router B Priority 50 HSRP Standby Group 1 Router B hears that router A has a higher priority, so router B returns to the listen state. Router A does not hear any higher priority than itself, so promotes itself to standby. Router A does not hear an active router, so promotes itself to active.

13 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v A router in the standby state: Is a candidate for active router Sends hello messages Knows the virtual router IP address HSRP Standby State

14 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v A router in the active state: Assumes the active forwarding of packets for the virtual router Sends hello messages Knows the virtual router IP address HSRP Active State

15 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v HSRP Configuration Commands Configure standby 1 ip Verify show running-config show standby

16 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Enabling HSRP on a Cisco router interface automatically disables ICMP redirects. Configuring an HSRP Standby Interface

17 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Displaying the Standby Brief Status Switch#show standby brief P indicates configured to preempt. | Interface Grp Prio P State Active addr Standby addr Group addr Vl Active local

18 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Summary Router redundancy allows two or more routers to work as a group to maintain forwarding of IP packets. A single default gateway or proxy ARP does not provide the redundancy required in a campus network. HSRP provides router redundancy to end devices. HSRP operates to provide nonstop path redundancy for IP. An HSRP-enabled router will exist in a specific state or transition through a series of states. HSRP is configured using the standby command. HSRP is enabled per interface.

19 © 2006 Cisco Systems, Inc. All rights reserved. BCMSN v