RE: HSRP OSPF [7:50626]
Your hosts use HSRP, to set the HOST ip default to the HSRP virtual Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=50628t=50626 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: HSRP OSPF [7:50626]
Gil Shulman wrote: Hi all, I know that I asked this question in the past, but I still have some problem with this issue. What I am trying to do is as follows: Site A| Site B __802.1q _ |_ | _ _|_ | SW-L3 |--| SW - L2 | | | SW - L3 |-| SW - L2| ||--|_| | ||-|_| // | / / // | / / // | Vlan2//Vlan3 / Vlan3 / / / Vlan 2 // / / / / / / _/__/ /__/ | || | |Host A | | Host B | |__| |___| The L-3 at site A and B holds two HSRP IP addresses for each Vlan, Vlan 2 Vlan 3. Host A B don't hold a static default gateway configuration, they are running an OSPF process and should learn their default gateway IP address via OSPF advertisements. Is it custom software or something? What ARE Host A and Host B? In general, IP hosts don't learn the default gateway from a routing protocol. AppleTalk and DECnet work that way. And a Novell IPX host learns about a router from the GetNearestServer interaction. But IP generally doesn't work that way. Instead, you manually configure a default gateway (or let the host learn it via DHCP). This has the obvious disadvantage that the default gateway could go down. That's why HSRP was invented. HSRP deals with the first hop workstation-to-router connection, in the control plane. OSPF and routing protocols deal with router-to-router paths in the management plane. A host can also learn about other routers through ICMP redirects. On a PC, you can isuse a route print command to verify whether a host has learned more than one way out, i.e. more than one workstation-to-router connection. Another alternative for IP workstation-to-router communication is the Router Discovery Protocol (RDP). RFC 1256 specifies the RDP extension to ICMP. With RDP, each router periodically multicasts an ICMP router advertisement packet from each of its interfaces, announcing the IP address of that interface. Workstations discover the addresses of their local routers simply by listening for advertisements, in a similar fashion to the method AppleTalk workstations use to discover the address of a router. When a workstation starts up, it can multicast an ICMP router solicitation packet to ask for immediate advertisements, rather than wait for the next periodic advertisement to arrive. Now, you may have a custom operating system or custom software that doesn't behave in the normal IP way, in which case, you need to tell us more about your situation. The question is, how can I advertise an HSRP IP address via OSPF routing protocol. I have been trying to achieve it by using the default-information originate always but the default gateway which the hosts gets is the real IP address of the interface. Perhaps the IOS developers never considered this a requirement and never made it possible to advertise the virtual HSRP address in an OSPF packet, since they solve two different problems. There may be a workaround, but I can't find one. Once again, I have to ask, what ARE these hosts? If they can talk OSPF, why don't you just let them use OSPF? OSPF can be designed to support the redundancy that you require. OSPF has support for quick convergence. HSRP solved a different problem, which was that IP, despite good routing protocols, didn't support quick convergence for the workstation-to-router first-hop problem. Priscilla Help will be most appreciated. Cheers, Gil ** The contents of this email and any attachments are confidential. It is intended for the named recipient(s) only. If you have received this email in error please notify the system manager or the sender immediately and do not disclose the contents to any one or make copies. ** eSafe scanned this email for viruses, vandals and malicious content ** ** Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=50636t=50626 -- FAQ,
RE: HSRP OSPF [7:50626]
I thought of one workaround but I don't know if it would work. Use a loopback interface. Perhaps OSPF would use the address in a way that would meet your needs. Then, would IOS let you say that the HSRP address is the loopback address also?? That's the part that I don't have time to test. It may be an off the wall suggestion, but your question is sort of off the wall too!? ;-) Priscilla Priscilla Oppenheimer wrote: Gil Shulman wrote: Hi all, I know that I asked this question in the past, but I still have some problem with this issue. What I am trying to do is as follows: Site A| Site B __802.1q _ |_ | _ _|_ | SW-L3 |--| SW - L2 | | | SW - L3 |-| SW - L2| ||--|_| | ||-|_| // | // // | / / // | Vlan2//Vlan3 / Vlan3 / / / Vlan 2 // / / / / / / _/__/ /__/ | || | |Host A | | Host B | |__| |___| The L-3 at site A and B holds two HSRP IP addresses for each Vlan, Vlan 2 Vlan 3. Host A B don't hold a static default gateway configuration, they are running an OSPF process and should learn their default gateway IP address via OSPF advertisements. Is it custom software or something? What ARE Host A and Host B? In general, IP hosts don't learn the default gateway from a routing protocol. AppleTalk and DECnet work that way. And a Novell IPX host learns about a router from the GetNearestServer interaction. But IP generally doesn't work that way. Instead, you manually configure a default gateway (or let the host learn it via DHCP). This has the obvious disadvantage that the default gateway could go down. That's why HSRP was invented. HSRP deals with the first hop workstation-to-router connection, in the control plane. OSPF and routing protocols deal with router-to-router paths in the management plane. A host can also learn about other routers through ICMP redirects. On a PC, you can isuse a route print command to verify whether a host has learned more than one way out, i.e. more than one workstation-to-router connection. Another alternative for IP workstation-to-router communication is the Router Discovery Protocol (RDP). RFC 1256 specifies the RDP extension to ICMP. With RDP, each router periodically multicasts an ICMP router advertisement packet from each of its interfaces, announcing the IP address of that interface. Workstations discover the addresses of their local routers simply by listening for advertisements, in a similar fashion to the method AppleTalk workstations use to discover the address of a router. When a workstation starts up, it can multicast an ICMP router solicitation packet to ask for immediate advertisements, rather than wait for the next periodic advertisement to arrive. Now, you may have a custom operating system or custom software that doesn't behave in the normal IP way, in which case, you need to tell us more about your situation. The question is, how can I advertise an HSRP IP address via OSPF routing protocol. I have been trying to achieve it by using the default-information originate always but the default gateway which the hosts gets is the real IP address of the interface. Perhaps the IOS developers never considered this a requirement and never made it possible to advertise the virtual HSRP address in an OSPF packet, since they solve two different problems. There may be a workaround, but I can't find one. Once again, I have to ask, what ARE these hosts? If they can talk OSPF, why don't you just let them use OSPF? OSPF can be designed to support the redundancy that you require. OSPF has support for quick convergence. HSRP solved a different problem, which was that IP, despite good routing protocols, didn't support quick convergence for the workstation-to-router first-hop problem. Priscilla Help will be most appreciated. Cheers, Gil ** The contents of this email and any attachments are
